• TABLE OF CONTENTS
HIDE
 Title Page
 Introduction
 The budget of irrigation water
 The role of public and private...
 Quality of the groundwater
 Concluding remarks
 Reference
 Tables I-VII
 Waterlogging and salinity in the...
 Waterlogging and salinity in the...
 Waterlogging and salinity in the...
 Back Cover






Group Title: Harvard University Center for Population Studies. Contribution - no. 10
Title: Waterlogging and salinity in the Indus Plain
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00053905/00001
 Material Information
Title: Waterlogging and salinity in the Indus Plain some basic considerations
Series Title: Harvard University Center for Population Studies. Contribution
Alternate Title: Pakistan development review
Physical Description: p. 331-370 : ; 25 cm.
Language: English
Creator: Dorfman, Robert.
Harvard School of Public Health -- Center for Population Studies
Publisher: Center for Population Studies, Harvard University
Place of Publication: Cambridge Mass
Publication Date: 1965
 Subjects
Subject: Waterlogging (Soils) -- Pakistan   ( lcsh )
Salinity -- India -- West Pakistan   ( lcsh )
Irrigation -- Pakistan   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: by Robert Dorfman ... et al..
General Note: "Reprinted from The Pakistan Development Review, Vol. V, No. 3, 1965, pp. 331-370."
General Note: Cover title.
Funding: Contribution (Harvard School of Public Health. Center for Population Studies) ;
 Record Information
Bibliographic ID: UF00053905
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 32962020

Table of Contents
    Title Page
        Title Page
    Introduction
        Page 331
        Page 332
        Page 333
    The budget of irrigation water
        Page 334
        A water budget based on an assumed cropping pattern
            Page 335
        Comparison of different budgets
            Page 336
        Ghulam Mohammad's budget for the northern zone
            Page 337
    The role of public and private tubewells
        Page 338
        Page 339
        Page 340
        Page 341
        Page 342
    Quality of the groundwater
        Page 343
        Salinity
            Page 343
            Page 344
        Extent of sodium hazard in mixtures of tubewell and canal waters
            Page 345
            Page 346
        Salinity control with mixtures of groundwater and surface water
            Page 347
            Page 348
            Page 349
        Effects of government and private tubewells on salt build-up and drainage
            Page 350
            Page 351
            Page 352
            Page 353
        "Horizontal" versus "vertical" drainage
            Page 354
            Page 355
        A comment of sub-irrigation
            Page 356
    Concluding remarks
        Page 356
    Reference
        Page 357
        Page 358
    Tables I-VII
        Page 359
        Page 360
        Page 361
        Page 362
        Page 363
        Page 364
        Page 365
        Page 366
        Page 367
        Page 368
        Page 369
        Page 370
    Waterlogging and salinity in the Indus Plain: Comment (Nazir Ahmad)
        Page 371
        Page 372
        Page 373
        Page 374
        Page 375
        Page 376
        Page 377
        Page 378
        Page 379
        Page 380
    Waterlogging and salinity in the Indus Plain: Comment (Frank M. Eaton)
        Page 381
        Page 382
        Page 383
        Page 384
        Page 385
        Page 386
        Page 387
        Page 388
        Page 389
        Page 390
        Page 391
        Page 392
    Waterlogging and salinity in the Indus Plain: Rejoinder (Ghulam Mohammad)
        Page 393
        Page 394
        Page 395
        Page 396
        Page 397
        Page 398
        Page 399
        Page 400
        Page 401
        Page 402
        Page 403
        Page 404
        Page 405
        Page 406
        Page 407
    Back Cover
        Back Cover
Full Text

Dr. P. E. HILDEBRAND
Chief Economist

/lo7. 0 1
Waterlogging and Salinity in the Indus
Plain: Some Basic Considerations


by
ROBERT DORFMAN, ROGER REVELLE, AND HAROLD THOMAS

-Comment by NAZIR AHMAD
-Comment by FRANK EATON
-Rejoinder by GHULAM MOHAMMAD





-:o:-





Reprint from
THE
PAKISTAN DEVELOPMENT REVIEW


Quarterly Journal of
Pakistan Institute of Development Economics
Karachi (Pakistan)


Volume V-Autumn 1965-Number 3 ,












Waterlogging and Salinity in the Indus Plain:
Some Basic Considerations
by
ROBERT DORFMAN, ROGER REVELLE, AND HAROLD THOMAS*
INTRODUCTION
It takes more than ordinary presumption for a group of strangers to recom-
mend changes in the efforts of a great nation to contend with a problem that
goes to the very roots of its social structure and its livelihood. Yet we did just
that in our Report on Land and Water Development in the Indus Plain[l]. We
hoped our recommendations would be considered sympathetically and debated
fully, that our sound suggestions would be adopted and our unsound ones
forgiven. All this has been granted us, and more.
The months since the Panel's report was prepared have been eventful for
the economic development of West Pakistan. It is hard to cast our minds back
to the gloom that filled the atmosphere when the Panel was convened. Food
production had been stagnant for the past several years, sem and thur were
spreading through the most productive portions of the Plain, expensive efforts
to control these twin menaces had been baffled. WAPDA knew, of course, that
in principle tubewells could do the job, but there were more failures to report
than successes. The yields of major crops were about what they had been five
years before, and population growth was outstripping production.
Now many things are hopeful. The watertable has been pumped down to
safe levels in large areas of the first experimental project. More than 2,000
government tubewells and perhaps 30,000 private tubewells are in operation.
Fertilizer use is likely to treble in the course of the Second Five Year Plan.
One does not debate stagnation any more.
This favorable turn of events has made parts of our report seem obsolete.
Tasks we almost feared to suggest have proven easy. Resources we did not
know existed have flowed abundantly. Some unforeseen difficulties have arisen,
but, on the whole, the surprises have been happy ones. The danger now, indeed,
*Dr. Robert Dorfman is Professor of Economics and Member of the Faculty of Public
Administration, Harvard University.
Dr. Roger Revelle is Richard Saltonstall Professor of Population Policy and Director of
the Center for Population Studies, Harvard University.
Mr. Harold A. Thomas, Jr. is Gordon McKay Professor of Civil and Sanitary Engineer-
ing and Member of the Faculty of Public Administration, Harvard University.







332 The Pakistan Development Review
is complacency-the premature conclusion that the programs already under-
taken will suffice. They will not. The first positive steps have brought dramatic
results becausethere was so much room for improvement in the cultivation of
the Indus Plain. But fundamental shortcomings persist. There is still much hard
work to be done. Just as our first message was one of hopefulness in a time of
gloom, so now we want to offer some sober appraisals in a time of confidence.

One of the central themes of our report was interaction. We found that
the agriculture of West Pakistan was beset by numerous deficiencies. Efforts to
correct any one of these could have only limited success, because the uncorrected
shortcomings would still set a low ceiling to agricultural productivity. On the
other hand, simultaneous measures to provide additional irrigation water;
reclaim deteriorated land; supply chemical fertilizers, plant protection, and im-
proved seeds; instruct farmers in the proper use of these materials and in modern
agricultural methods; increase the ease and rapidity of loans to farmers; and
improve marketing procedures and facilities-all concentrated on the same
area-would be mutually supporting and would yield far greater increases in
output than the same efforts scattered over different places. For these reasons
we recommended the formation of the Land and Water Development Board
and of local administrations, each responsible to the Board for supervising
physical improvements and a number of agricultural programs in a single
compact area. Because Pakistan has a limited supply of administrative resources,
we recommended the strategy of starting project areas in succession, with
development of no more than about a million acres being undertaken in any
one year. We still adhere, in the main, to this broad concept. But now it appears
that we overestimated some of the difficulties. Since the publication of our
report, the farmers of West Pakistan have demonstrated more initiative and
more willingness to adopt modern agricultural practices than we anticipated.
This is indicated by the rapid spread of private tubewells-about 6,500 a year-
and by the eager adoption of chemical fertilizers-usage increasing at about
20 per cent per year recently. Furthermore, it seems evident that the distribution
of fertilizer, seeds, and other materials of agriculture can be accomplished effi-
ciently through ordinary commercial channels. Thus, the agricultural administra-
tion can concentrate on providing water, agricultural advisory services, credit,
and storage and marketing facilities, leaving the problems of distribution of
agricultural materials and even some of the work of supplying irrigation water
to private initiative. The resulting economies in the utilization of scarce admin-
istrative and technical manpower may permit a considerable acceleration of the
program.








Dorfman, Revelle and Thomas: Waterlogging and Salinity 333

A second theme implicit throughout the Panel report was integration-the
hydrological problems of the Indus Plain can best be handled on a unitary or
"systems" basis. Three kinds of integration are involved.
1) The Plain as a whole and its water supply must be considered as a unit.
What is done to irrigate farm fields in former Punjab and Bahawalpur pro-
foundly affects former Khairpur and Sind. The total water requirement for given
cropping patterns and intensities in areas of given size throughout the Plain
depends primarily on the potential evapotranspiration in these areas. It must
be entered in any budget of irrigation water. But more important, because water
in the Indus Plain is scarcer than arable land, is the total water supply from
rivers and rain, and from surface and underground storage. We want to know
the supplies (from both irrigation and effective rainfall), that can be made
available during each month in each area at given levels of development of water
structures. Comparisons need to be made of the social and economic costs
and benefits of water developments in the Northern and Southern regions
and their sub-regions. For each sub-region, with any given cropping pattern
and intensity, the available water supplies will determine the size of the cropped
area. The ultimate potential water supply for irrigation in the Plain as a whole
is particularly significant, because it will fix the ultimate dimensions of the gross
sown area, that is, the product of the cropping intensity times the net cultivated
area. This must be the primary boundary condition in long range planning for
agricultural development. The degree and speed of approach to this boundary
condition are crucial for shorter range planning.
2) Irrigation water supplies from rivers and surface storage and from the
underground reservoir should be managed as a single system. There is a marked
seasonal variation in river flows, and a lack of concordance between these flows
and the crop water requirements. At the same time, the unit costs of surface
storage are high, and good reservoir sites are scarce. Consequently, the propor-
tion of river waters effectively usable for irrigation can be raised near to its
potential level only if sufficient underground water supplies are also available,
at the right times. Conversely, the full potential of the underground reservoir
can be realized, and a high percentage of recovery of the seepage from canals,
water courses, and field percolation attained, only if river waters are available
at the right times and places for mixing with relatively salty or sodium-rich
underground waters.
3) Supply and drainage of irrigation water should be closely integrated. To
maintain soil salinity and alkalinity control, a substantial fraction of the irriga-
tion water applied to the fields must be drained off, either in conveyance
channels or by percolation into the ground, and hence cannot be used consump-








334 The Pakistan Development Review
tively in evapotranspiration by the crops. To minimize this fraction, to
postpone investments for drainage, conveyance channels, and to reduce the
ultimate costs of drainage structures, it is necessary to use the underground
reservoir as an integral component of the drainage system. Any ultimate
tubewell system should be designed to accommodate both irrigation supply and
drainage.
THE BUDGET OF IRRIGATION WATER

In a steady state, rivers and rainfall are the only sources of supply for water
in the Indus Plain. While there are significant fluctuations from year to year,
the average annual volume of river flow is about 136 MAF (million acre feet),
and the "effective" rainfall perhaps another 10 MAF. Of the total, say 145
MAF, only about a third was available in 1960 for beneficial use by crops. A
large part of the remaining two-thirds flowed to the sea unused during the mon-
ths of the summer monsoon; a smaller part was lost in non-beneficial evapo-
transpiration from rivers, canals, and water courses, and their soggy banks, and
from field ditches and edges. More than a third of the water diverted from the
rivers into canals seeped into the ground, as did a small part of the river flows.
A major fraction of the seepage was ultimately lost in non-beneficial evapora-
tion from waterlogged and saline areas, where the watertable stood close to the
surface.

A principal objective of water development in the Indus Plain is to contribute
to increasing agricultural production by increasing the fraction of the total
water supply that is beneficially used. Most of the beneficial use will be in
evapotranspiration by crop plants, which. from the standpoint of water transfer,
behave much like little evaporating pans. But part of the beneficial use-ideally
10 to 15 per cent of the water applied to the fields-will be in achieving and
maintaining a low salt content in the soil. This portion of the water will be
used to wash away the salts already present or carried onto the fields with the
irrigation water.

In the ultimate water development, the water running to the sea will consist
very largely of these irrigation return flows. They will be needed to carry salt
off the fields and out of the Plain. The principal device for increasing the usable
supplies will be water storage during the monsoon months, either in surface
reservoirs or underground, and the use of this stored water during the remainder
of the year. As much as possible of the seepage water will be recovered, chiefly
by pumping from wells. Part of the seepage enters the ground in areas of high
groundwater salinity such as characterize the Southern Zone. It will not be
recoverable for beneficial use, and will have to be wasted to the sea or to desert








Dorfman, Revelle and Thomas: Waterlogging and Salinity 335
salt lagoons. Non-beneficial evapotranspiration losses will be minimized by
careful water management, but these losses may actually be increased by surface
storage.

Taking all factors into account, the Water and Power Development Auth-
ority of West Pakistan (WAPDA) has estimated that after construction of suffi-
cient storage facilities, an average of some 114 MAF per year of river waters
could ultimately be made available at the water courses leading to the farm
fields[2]. The remaining 22 MAF would be lost, chiefly by non-beneficial eva-
potranspiration from reservoirs, link canals, rivers, irrigation canals, water
courses, and from the border areas of all these various kinds of channels.
WAPDA's estimate is based on an ultimate steady state in which only the aver-
age annual water supplies from rivers and rain can be considered. The approach
to such a steady state will inevitably be slow and expensive, because it involves
very extensive construction of dams, conveyance channels, and other surface
water structures. In the meantime, there is an overwhelming need to increase
agricultural production in West Pakistan as quickly and inexpensively as possible.
Although chemical fertilizers, improved seeds, and other production factors can
contribute to this end, water is the key. Here, during the transition period, we
can utilize one of the great natural resources of the earth-the enormous pool
of fresh groundwater that underlies the Northern Zone of the Indus Plain, and
is equal in volume to ten times the annual flow of the rivers.
In making up irrigation water budgets for this transition period, we can
base our calculations either on the water requirements for an assumed cropping
pattern, cropping intensity, and net cultivated area, or on the estimated supplies
that can be made available at a particular time with a given level of expenditures
for water development. A budget based on assumed crop requirements has the
advantage that the water needed during each month can be calculated. A budget
based on the anticipated availability of supplies can give only seasonal totals
until a cropping pattern is specified, but it has the great merit that comparisons
of different cropping patterns can be made and the economic optimum chosen.
A Water Budget Based on an Assumed Cropping Pattern
Table 1 gives an irrigation water budget based on requirements for assumed
cropping patterns and intensities on a net cultivated area of 19.4 million acres in
the Northern Zone, and 7 million acres in the Southern Zone. The budget is
computed from data given in a report by Harza Engineering Company Internat-
ional, made in 1963 [31. The total irrigation requirement at the water courses
is 108 MAF and the beneficial use on the fields evapotranspirationn by crops
plus leaching) is 83 MAF.








The Pakistan Development Review


These water supplies are to be obtained by river diversions of 103 MAF
at the canal heads and by pumping 36 MAF from tubewells. Only 72 MAF of
the river diversions actually reach the water courses; the remainder is lost by
seepage and by non-beneficial evapotranspiration. It is assumed that seepage
into the ground from link and irrigation canals, water courses, and farm fields
will balance the volume of water pumped. About 13 MAF of the diversions
at canal heads are to be made possible by enlarging the canal system. All of
the pumped water and nearly two-thirds of the canal water are to be used in the
Northern Zone, with the result that about three-fourths of the total water supply
is to be concentrated there.
In Table II we have computed from Harza's data the water budget by
months. This table gives the interesting result that through careful coordination
of tubawall and canal supplies it is possible, without enlarging the canals, to in-
crease the beneficially usable river diversions during the kharif season by about
the same amount as Harza calculates could be accomplished by canal enlarge-
ment.
Comparison of Different Budgets
In Table III, we have shown a comparison of the Harza "Programme"
budget with that given in the Panel Report and with a budget for the Northern
Zone computed from data given by Ghulam Mohammad[4]. The chief differ-
ence between our budget and Harza's is that ours was not based on crop require-
ments but on an estimate of the supplies that could be made available fairly
quickly and with total expenditures much lower than those ultimately needed.
We assumed construction of Tarbela and Mangla Dams to hold 12 MAF of
live storage, and of a widespread grid of tubewells. These would be used to re-
cover all possible recharge and to mine the aquifer in the Northern Zone down
to a depth of about 100 feet. Another major difference is that we allocated much
more water to the Southern Zone, both from canals and from tubewells. Finally,
we attempted to work out a budget which would closely approach the ultimate
potentialities of the river supplies in the Indus Plain, on the premise that the
most rapid possible approach to the ultimate water potential offers the greatest
opportunities for agricultural development and for economic and social progress.
This premise receives some justification from the cost-benefit analysis of two
alternative design schemes for the Northern Zone given in Chapter 7 of the
Panel Report [1]. The first design involved the mining of the entire aquifer to a
depth of 100 feet and provision of a firm water supply to 16.4 million acres under
intensive cultivation. In the second design, the ultimate depth of the watertable
was set at 50 feet; water would be pumped only at a rate sufficient to recover
seepage losses in the distribution system and recharge from rivers and rain.








Dorfman, Revelle and Thomas: Waterlogging and Salinity 337
While the second design entailed a much smaller investment in wells
and would require considerably smaller power costs than the first, it had the
marked disadvantage of providing water sufficient for the intensive development
of only 11.6 million acres of cultivated land. This area is a great deal less than
that occupied at the present time. Farming could be maintained over the present
area only at the cost of a relatively low intensity of cultivation.
The first scheme was shown to be economically more efficient than the
second when the discount rate was taken as 4 per cent per year. At this discount
rate, the present value of the time stream of benefits and costs of the mining
scheme was 8 per cent larger than that in which recharge only was pumped.
Moreover at all other discount rates from 0 to 10 per cent per year the first
scheme outranks the second. The ranking is insensitive to the discount rate and
the Panel Plan with 100-foot mining and large scale tubewell development affords
a better investment than the second scheme.
The opinion has been expressed by some that the Panel Plan did not suffi-
ciently take into account the difficulty that in mining over time the quality of
groundwater will deteriorate due to the fact that salinitygenerallyincreases with
depth. The Panel examined many hundreds of profiles of salinity and found that
while this increase occurs in many places-indeed most places-the reverse is
also true, and the average increase in salinity in 100 feet of depth was not large.
Moreover, there are factors that operate to improve the quality of the ground-
water over time. Several of the curves of salinity vs. time [1, Chapter 7J Fig-
ures 7.18 and 7.19 show a decrease in salinity after 30 years of operation.
This decrease would have been even greater if the salt-flow model had been
run under the plausible assumption that with a low watertable some of the salt
leached below the root zone would be stored permanently in the soil pores
above the watertable.

The Panel's principal argument for mining, however, did not rest upon the
foregoing economic analysis. A more realistic but less quantifiable argument is
that until a very large amount of surface storage is built, intensification of water
use and cultivation can be accomplished in the Northern Zone only by mining
or by greatly reducing the area of cultivated land. The latter would result in
large social costs and perhaps monetary costs of resettlement and other
adjustments.
Ghulam Mohammad's Budget for the Northern Zone[4]
A somewhat similar argument applies to the budget given by Ghulam Mo-
hammad. Although he does not recommend a marked reduction in net cultivated
area, his gross sown area in the Northern Zone would be much smaller than








338 The Pakistan Development Review
ours or Harza's and his cropping intensity lower. He assumes almost as much
diversion of river waters at canal heads, but only 16 MAF of tubewell supplies,
because he believes that about half the seepage water from canals and water
courses, after mixing with the underground water, will be too salty or too
sodium-rich to be usefully recovered by pumping. Although he does not
mention the Southern Zone, by implication he allots it only a minor fraction of
the canal diversions, since he states that his diversion scheme for the Northern
Zone follows Harza's. He neglects non-beneficial evapotranspiration, but we
have included this in recomputing his budget.
THE ROLE OF PUBLIC AND PRIVATE TUBEWELLS
At the time the Panel Report was written, the vigorous growth of privately
installed and operated tubewells was not anticipated. About 30,000 such tube-
wells have now been installed, and they are making a significant contribution
to the productivity of agriculture in West Pakistan. This contribution will grow
as the private tubewells continue to be installed at a rate of several thousand
units a year. The policy of the government in designing new SCARP and new
public tubewell fields should, of course, take this development into account in
order that the maximum benefit to the economy can be realized from the public
and private tubewells together.
It must not be thought that this is simply a question of public versus private
ownership. The public and the private tubewells differ from each other techno-
logically and they will be operated in accordance with different principles and
purposes. From the planner's point of view each is suitable for obtaining a
somewhat different set of goals. The more appropriate mode for developing
the underground water resources of any particular area will depend upon the
conditions and problems prevalent in that area. The private tubewell owners
have already recognized this. Although the private tubewells are quite widely
dispersed throughout the irrigated region of the Plain they tend to be much
more heavily concentrated in the upper regions of the doabs than elsewhere.
We can make only a few tentative remarks on the four-way integration of public
tubswells, private tubewells, canals, and drainage works, and feel that the
situation must be watched closely and a sound policy developed in the light
of experience. Our understanding of the operating characteristics of the private
tubewells is especially deficient in spite of the excellent beginning that has been
made by the two sample surveys of their operations, one conducted by Ghulam
Mohammad [5] and the other by Harza Engineering Company International [6].
From a technical point of view the major differences between the two types
of well are in capacity and depth. The public wells are designed for a capacity
of from 3.5 to 4.5 cusecs (7 to 9 acre feet per day) and have a draft of from








Dorfman, Revelle and Thomas: Waterlogging and Salinity 339
250 feet to 350 feet. They are intended to provide water to an area of 600 acres
or more each. The private wells are much smaller. Typically their flows are
from 1 to 1.25 cusecs (2 to 2.5 acre feet per day) and their drafts are typically
about 100 feet. The usual practice is for the private wells to serve an area of
approximately 60 acres, or 1/10 that of the public wells.

From an economic point of view, it is pertinent that the public wells are
built with imported components for the most part, while the private wells use
equipment of domestic manufacture. The private wells, therefore, economize
on the use of foreign exchange and also contribute to the accumulation of
domestic manufacturing capacity and experience.
It is evident that the larger public wells are more efficient technically than
the private ones. As will be discussed more fully in a later section the deeper
draft of the large wells slows down the rate of salt build-up in the groundwater
reservoir which is an inevitable result of the vertical drainage entailed by either
system. The larger wells with their larger and more rugged pumps and motors,
are also more efficient mechanically. It is very difficult to compare the costs
of the two types of wells. Ghulam Mohammad has done so [7] and come to the
conclusion that private wells can pump underground water more cheaply
than government wells. This finding, however, should not be regarded as con-
clusive. The basic difficulty, aside from the fact that the government wells and
the private ones are not in strictly comparable locations, is that different systems
of accounts are used in computing the costs of the two systems of well. The
cost accounts for government wells include charges for many items that the
account for private wells omit, because the recorded cost for private wells
incorporates only the out-of-pocket cost of the well owners. Costs of planning,
supervision, and provision for contingencies, for example, are included in the
government accounts but not in those for private wells, although the same
economic functions must be performed in both instances. A good justification
can be given for excluding the imputed costs of such functions from the estimate
of the cost of private tubewells. These exclusions do, however, impair the compar-
ability of those costs with the cost of government wells. The government accounts
include costs for draining saline effluent and for power transmission; private
accounts do not. And there are many other similar items.
With these reservations in mind, we have tried, in Table IV, to place the
costs of water pumped by private and government wells on a comparable basis,
relying largely on Ghulam Mohammad's data. Costs of drainage are omitted;
they would be somewhat larger for the private wells than for the government
ones because the quality of the effluent would deteriorate more rapidly from
the shallower wells. All costs for the provision of power are included in the








340 The Pakistan Development Review

charge of Rs. 0.08 per kwh, used for both types of installation. In other respects
too the two systems have been put on as comparable a basis as possible, as the
source notes indicate in detail.
The computation shows that water pumped by private tubewells costs about
8 per cent more than water pumped by government wells. In view of the in-
herent lack of precision of such a calculation this difference should not be taken
seriously; to all intents and purposes the calculation indicates that the costs
of water from the two types of well are approximately the same. It should be
noted, however, that in Table IV we have assumed the same load factor for
both types of well, approximately 25 per cent. This load factor accords with
the recorded experience with private wells but the public wells in the SCARP
have been operated at a load factor of about 60 per cent. If the more intensive
use of government as compared with private wells should persist, then the
government wells will show an appreciable economy in comparison with the
operating costs of the private wells.
At any rate, such cost comparisons cannot be decisive, because, as remarked
above, the private and the public wells serve different purposes in the overall
development of the Indus Plain. Private wells have been used only for very
local supplementation of the suppliesof canal water. Water provided by private
tubewells is approximately four times as expensive as government canal water
to the owner of the private well, and to a farmer who purchases from a private
well owner, the discrepancy is even greater. Private wells will therefore be deve-
loped only in areas that have adequate supplies of high quality groundwater
and they will be used mainly to fill in gaps in the supply of canal water. They
have not been installed thus far in localities where the groundwater is too saline
to be applied to the land without dilution with canal water. From the farmer's
point of view the supply of government water from either wells or canals is
less reliable than that of water provided by a locally owned tubewell and the
government wells cannot be adapted as flexibily to day by day changes in the
local requirements for irrigation water. On the other hand, the government
wells can be used for the dilution of saline groundwater, for reclamation of
deteriorated lands, and for closely integrated management of both ground and
surface water supplies.
The advantage of closely coordinating canal diversions and groundwater
withdrawals can be seen from a simple calculation based on the data in Table II.
Suppose in the first instance that Mangla and Tarbela Dams are operating but
that no tubewell water is available, and that the maximum amount of canal
water available during any month in kharif is 12.4 MAF at the canal heads,
or 8.7 MAF at the water courses, this being the maximum capacity of the canals.








Dorfman, Revelle and Thomas: Waterlogging and Salinity 341

This is only 65 per cent of the water requirement of 13.4 MAF in June, the
critical month, so that under these conditions the entire program would aveh
to be scaled down by 35 per cent. This scaled-down program would use
only a total of 41 MAF of canal water at the water courses in kharif (59
MAF at the canal heads). On the other hand, if tubewells capable of providing
4.7 MAF per month (equivalent to a total well capacity of 80,000 cusecs) are
available and suitably distributed over the cultivated area, then the required
13.4 MAF can be delivered to the water courses in June. The total delivery
capacity of the canals can be utilised for irrigation from May through September,
and 49 MAF of canal water can be delivered usefully to the water courses,
corresponding to a diversion of 70 MAF at the canal heads. The tubewells not
only supply 14 million acre feet in kharif but they make it possible to use 11
MAF of river water that would be wasted without them.
Similar calculations can be made for other assumed canal capacities, and
they show in each case that the volume of beneficially usable river water during
kharif can be increased by supplementing canal flows with sufficient pumping
at the proper times. The same utilization of surface water could be attained
by enlarging the canals. But by coordinating canal and tubewell operations,
investments for enlarging and modifying the canal system can be minimized.
Even more important, difficulties of silting and erosion, and of inadequate check
structures on distributaries and water courses can be at least partly avoided.
With the "regime" canals of the Indus Plain, these difficulties arise from large
differences in canal flows during different months.
This calculation, naturally, somewhat overstates the case. An accurate
computation would have to take account of the differing canal capacities and
patterns of monthly irrigation requirements in the different canal systems, of
the need for surface water to dilute saline groundwater, and of other complica-
tions. And, of course, perfect coordination cannot be attained. But the moral
is clear that a closely integrated operation of tubewells and canals greatly in-
creases the efficiency with which surface supplies can be used. This close integra-
tion can be more easily attained where government wells are installed than
where private ones are. But it may be possible to integrate private wells with
the canal operations through wide dissemination of information about planned
canal operations and economic pricing policies for both canal and tubewell
water. Even before adequate well capacity is installed throughout the Northern
Zone, sufficient capacity may be developed in certain canal commands to test
the scheme outlined in Table II, particularly the effectiveness of the incentives
for the private operators.
One reason for the superior integration of government tubewells with canal
operations is that this integration will require some changes from the historical








342 The Pakistan Development Review
patterns of canal diversions. It may be necessary or desirable to transfer surface
supplies from one region to another, and to make good the transfers by addi-
tional pumping in areas underlain by high quality groundwater. These transfers
will be more acceptable if reductions in surface water supplies are replaced
by government-provided groundwater, but not if the deficit has to be made
good by privately pumped groundwater, which, we have seen, is several times
more expensive than canal water (see, for example [1, p. 280]).
Among the major benefits of the use of tubewells are the control of the
level of the ground watertable and the reclamation of waterlogged and saline
land. For these purposes government tubewells are much better adapted than
private ones. The experience in SCARP I makes it clear that controlling the
watertable requires coordinated operation of many tubewells covering a large
area. Reclamation operations even when economically justifiable are not com-
mercially attractive to private tubewell owners.
Private tubewell operations are also poorly adapted to exploiting the ground-
water in regions where pools of poor quality water are interspersed among the
good. If the level of the watertable is drawn down in regions underlain by high
quality water to depths much below the average level, the neighboring saline
water is likely to infiltrate and to contaminate the remaining reservoir of sweet
water. The long lives of some of the private tubewells indicate that this danger
is not always present but it is clearly real in some places. Until accurate and
detailed maps of groundwater quality can be made we must proceed with
caution to avoid spoiling the underground water supplies.
Excessive lateral migration and mixing of saline with sweet groundwater
can be prevented by operating all wells in a region as components of an integ-
rated irrigation and drainage system, which is difficult when the wells are
privately owned. On the other hand when problems of salinity control are likely
to occur these problems may be intensified if the wells are operated by single
farmer or small groups of farmers each pumping as much good quality water
as he needs for his immediate use. Experience has been unsatisfactory in other
countries when large numbers of privately owned and individually operated wells
have been installed in regions where there are marked variations in the areal
and vertical distribution of groundwater salinity.
The social effects of the private and public tubewells are also somewhat
different. Water pumped by the government wells is available on the same
terms to all farmers, while only the larger farmers, those operating farms of
25 acres or more, are likely to find it economical to install private tubewells.
Small farmers can and do purchase tubewell water from the larger farmers,
but the surveys available indicate that the prices are so high that the cost of








Dorfman, Revelle and Thomas: Waterlogging and Salinity 343
installing a private tubewell is amortized in a period of 2 or 3 years. Therefore,
in regions developed by private tubewell owners the underground water supplies
will benefit primarily the larger farmers. Ordinary market forces cannot be
expected to moderate the price of private tubewell water to small farmers be-
cause each small farmer will be located in a position that can be served by
at most one or two large tubewells. In this circumstance, it may be adviseable
to regulate the price of private tubewell water just as the terms for farm tenancy
are now regulated. This regulation should not be so stringent that it erodes
substantially the incentive for the installation of private tubewells where they
are appropriate.

This all adds up to a complicated mesh of considerations that cannot be
resolved finally until we have more experience with the operation of the private
wells. Tentatively it appears that the private wells, being more responsive to
local day-by-day requirements, are preferable in areas where they can be installed
and operated profitably, and where considerations of control of groundwater
quality are not overriding. They are managerially simpler to operate and they
mobilize resources of private management and capital the government cannot
tap. But where land reclamation or groundwater quality control are command-
ing considerations, and in areas from which surface water supplies should be
diverted in the interests of overall economy, then the government tubewell
developments are the method of choice. In the long run, there is also the ques-
tion of coordinated op-ration of the canals and the tubewells in order to maxi-
-mize the benefit from the high river flows of summer. We have suggested that
it may be possible to do this with either private or public wells, but this should
be tested. In any case, both sorts of wells have useful roles to play in the over-
all development of the Indus Plain.
QUALITY OF THE GROUNDWATER
Serious questions have been raised, most forcibly by Ghulam Mohammad
[4], about the quality of the underground water in the former Punjab and
Bahawalpur. These concern the salinity, or total salt concentration, of the
water and the possibility of soil damage from an excessive sodium content in
the presence of relatively high concentrations of carbonate and bicarbonate ions.
Insufficient information exists to discuss such other problems as the potential
hazards from boron, but we believe these are small.
Salinity
The Ground Water Development Organization ofthe IrrigationDepartment,
and later the Water and Soil Investigation Division of the West Pakistan Water
and Power Development Authority, made several thousand chemical analyses
of water samples from nearly a thousand test holes, throughout 34 million








Dorfman, Revelle and Thomas: Waterlogging and Salinity 343
installing a private tubewell is amortized in a period of 2 or 3 years. Therefore,
in regions developed by private tubewell owners the underground water supplies
will benefit primarily the larger farmers. Ordinary market forces cannot be
expected to moderate the price of private tubewell water to small farmers be-
cause each small farmer will be located in a position that can be served by
at most one or two large tubewells. In this circumstance, it may be adviseable
to regulate the price of private tubewell water just as the terms for farm tenancy
are now regulated. This regulation should not be so stringent that it erodes
substantially the incentive for the installation of private tubewells where they
are appropriate.

This all adds up to a complicated mesh of considerations that cannot be
resolved finally until we have more experience with the operation of the private
wells. Tentatively it appears that the private wells, being more responsive to
local day-by-day requirements, are preferable in areas where they can be installed
and operated profitably, and where considerations of control of groundwater
quality are not overriding. They are managerially simpler to operate and they
mobilize resources of private management and capital the government cannot
tap. But where land reclamation or groundwater quality control are command-
ing considerations, and in areas from which surface water supplies should be
diverted in the interests of overall economy, then the government tubewell
developments are the method of choice. In the long run, there is also the ques-
tion of coordinated op-ration of the canals and the tubewells in order to maxi-
-mize the benefit from the high river flows of summer. We have suggested that
it may be possible to do this with either private or public wells, but this should
be tested. In any case, both sorts of wells have useful roles to play in the over-
all development of the Indus Plain.
QUALITY OF THE GROUNDWATER
Serious questions have been raised, most forcibly by Ghulam Mohammad
[4], about the quality of the underground water in the former Punjab and
Bahawalpur. These concern the salinity, or total salt concentration, of the
water and the possibility of soil damage from an excessive sodium content in
the presence of relatively high concentrations of carbonate and bicarbonate ions.
Insufficient information exists to discuss such other problems as the potential
hazards from boron, but we believe these are small.
Salinity
The Ground Water Development Organization ofthe IrrigationDepartment,
and later the Water and Soil Investigation Division of the West Pakistan Water
and Power Development Authority, made several thousand chemical analyses
of water samples from nearly a thousand test holes, throughout 34 million







344 The Pakistan Development Review
acres of the Northern Zone. The total salt contents are summarized in Table V.
We see that 16.3 million acres in the canal-irrigated regions of the former
Punjab, and 2.0 million acres in canal regions of former Bahawalpur, overlie
groundwaters with a salt content of less than 1000 ppm. These sweet water
zones make up 70 per cent and 39 per cent, respectively, of the gross area in
the canal-irrigated regions. Out of the entire 34 million acres, 21.2 million acres,
over 62 per cent, have a salinity of less than 1000 ppm. There is no question
that water in this salinity range can be used for irrigation, either directly or
when suitably mixed with canal water. The area in the canal-irrigated regions
underlain by this relatively high-quality water is close to the maximum net
cultivated area, contemplated in Tables I and III for intensive cultivation.
To achieve the potentialities of the Indus Plain, it will be necessary to
recapture as much seepage as possible from water courses, canals, and fields.
Part of this seepage occurs in areas of salty groundwater. In the Panel Report,
we assumed that groundwater with a salt content up to several thousand ppm
could be used for irrigation if it is mixed with the river waters, which have a
salinity of about 250 ppm. It is encouraging to note from Table V that less
than 13 per cent of the entire Northern Zone is underlain by water with a
salinity of more than 5000 ppm. In the canal irrigated regions, only 11 per cent
of the gross area has a salinity in excess of 5000 ppm; 77 per cent has a salinity
less than 2000 ppm.

In the Panel Report, we defined non-saline and saline areas as those under-
lain respectively by groundwater with a salinity less or more than 2000 ppm.
The average salinity of water samples from the non-saline area (constituting
77 per cent of the canal region) is 750 ppm; the average for the saline area
(constituting 23 per cent of the canal region) is 6000 ppm. The latter value is
high because of the very high salinity of a few of the samples. If we consider
instead the sizes of the areas overlying waters of different salinity, we can estimate,
from Table V, that in half the saline area the groundwater has less than
5000 ppm, averaging 3350 ppm. A good deal of this water in the "favorable"
half of the saline area can be used for irrigation, if it is sufficiently diluted with
canal water.

We conclude that over the Northern Zone the distribution of groundwater
salinity is so favorable that extensive exploitation of nearly all the area of the
underground aquifer is warranted. In order to do this safely, however, highly
saline waters must be pumped from underground and carried out of the region,
perhaps to desert salt lagoons.







Dorfman, Revelle and Thomas: Waterlogging and Salinity 345
Extent of Sodium Hazard in Mixtures of Tubewell and Canal Waters
The Panel became aware during its first visit to Pakistan of the sodium hazard
associated with use of groundwater in some areas. In evaluating the suitability
of water for irrigation, an important parameter is the potential extent of ex-
change of sodium ions between the water and the dispersed phase of the soils.
Absorption of too many sodium ions by certain soil clay minerals can cause
excessive swelling of the dispersed phase. This may drastically reduce the per-
meability and porosity of the soil and decrease or destroy its agricultural value.
The amount of sodium absorption depends on two factors: i) the ratio of sodium
ions to the square-root of one-half the sum of calcium and magnesium ions
in the soil water-this is called the "Sodium Absorption Ratio" (SAR); ii) the
chemical and mineralogical nature of the clay fraction of the soils.
The SAR of the soil water depends on the SAR of the applied irrigation water
and on its content of bicarbonate and carbonate ions. The latter tend to pre-
cipitate calcium in the soil as CaCO3, and thereby to raise the SAR. In assess-
ing the effect of bicarbonate and carbonate, the Panel used both the "residual"
sodium carbonate (excess of carbonate and bicarbonate over calcium and magne-
sium in the applied water) and a new criterion developed by Dr. C. A. Bower,
Director of the United States Salinity Laboratory at Riverside, California, and
a member of the Panel. This criterion combines a modified Langlier index with
the Sodium Absorption Ratio [8] to give a calculated "Exchangeable Sodium
Percentage" (ESP).
Clays may be divided into three groups that have markedly different tenden-
cies to swell with absorption of sodium ions: 1) the kaolin group with a 1:1 lattice
type; ti) the hydrated mica group with a 2:1 lattice type; and iii) the mont-
morillonite or expanding lattice group with a 2:1 lattice type. Soils containing
clays of the montmorillonite group (beidellite, saponite, etc.) have a large intra-
micellular surface and a strong tendency to expand when the soil water has a
relatively high ESP. The kaolin minerals kaolinitee, nacrite, metahalloysite, etc.)
and hydrated mica minerals (illite, chlorite, etc.) have fixed lattices and exhibit
much smaller hydration and absorptive properties. Soil samples from the irri-
gated regions of West Pakistan that were examined by the Panel contain clays
predominantly of the non-expanding type such as illite and chlorite. These
soils tolerate larger concentrations of exchangeable sodium in irrigation water
than soils containing montmorillonitic clays.

After collecting and examining field data available in 1961 relating to the
chemical composition of soil and water, the Panel decided that we had in-
sufficient information to establish the magnitude of the sodium hazard. Accord-







346 The Pakistan Development Review
ingly, we arranged to carry out an investigation under Dr. Bower's guidance.
During 1962 and 1963, chemical data from West Pakistan were sent to Riverside,
and also to Cambridge, Massachusetts, for statistical analysis and evaluation.
Dr. Bower carried forward a theoretical analysis of the various chemical pro-
cesses at the soil-water interface that govern the uptake of sodium ions upon
the clay lattice. This analysis was published by Bower and Maasland [8].
Maasland, Priest, and Malik [9] have summarized the results of the field and
laboratory tests as well as the analytical studies.
In the water budget presented in Chapter 7 of the Panel Report, the pre-
dicated constraints pertaining to limiting mixing ratios of groundwater to surface
water in the saline and non-saline areas were based on analyses of water from
tubewells in the SCARP I project area and of water samples from elsewhere
in the Northern Zone, made by the Water and Soils Investigation Division of
WAPDA. The results are contained in items I C 7(a) and 7(c)(1)(2)(3) and (6)
of the water budget. We estimated that in the non-saline areas of the former
Punjab and former Bahawalpur the dilution ratio for one-third of the wells
must be at least 1:1, while in the saline areas one-half the wells must have a
dilution ratio of 2:1. These degrees of dilution were adequate to reduce the
ESP to the range of 15 to 20 which we considered as generally safe for the soil
types of the Northern Zone. As Maasland, Priest, and Malik show, reduction
,of the ESP to the commonly accepted "safe" range of 10-15 would require
much higher dilution ratios. For example, in 40 per cent of the wells .in the
non-saline area, 2.5 parts of canal water would be needed for 1 part of tubewell
water. However, a reduction to this extent is probably not necessary with the
mica-type clays of former Punjab and Bahawalpur.
The Panel Report states the mixing ratios of canal to tubewell waters, as
well as other design constraints based on groundwater salinity, in the form
of inequalities, rather than equities. In the final solution (IC 7(e)) for the water
budget, several of these constaints were not binding. For example, if 77 per
cent of the canal water is used in the non-saline area (see, Table III), the ratio
of canal water to tubewell water at the water courses in the non-saline area is
70 per cent greater than that specified in the Report as a lower limit. In the
saline area, if "skimming" wells can be used to recover canal seepage before
it has become mixed with the salty underlying groundwaters, the salinities of
the tubewell water may be lower than the calculated values.
The Panel Report contemplated that only 75 per cent of the area in the
non-saline zone and 50 per cent of the area in the saline zone were to be cultiv-
ated. It should be possible to "pick and choose" favorable locations. In the
non-saline zone, the groundwater over the best 75 per cent of the area. may








Dorfman, Revelle and Thomas: Waterlogging and Salinity 347
be expected to have a lower salinity and ESP than that predicated in the con-
straints of the water budget. As we showed above in discussing the distribution
of salinity in the saline zone, the best half of this zone should overlie water
with an average concentration of 3350 milligrams per litre.

On the basis of presently available water quality data, it is not possible to
specify mixing ratios and irrigation rates or times in the various project areas
with any degree of certainty, and the Panel made no attempt to do this. Any
practical irrigation scheme depends on several factors. A water supply of a
given salinity and alkalinity suitable for one soil type may be unsuitable for
another. A given irrigation time or leaching rate appropriate for one blend of
surface and groundwater may be inappropriate for another. A program of
water management for sugarcane may be unsatisfactory for pulses. It may be
expected that practices will vary over a wide spectrum in the various canal
commands and project areas of the Plain, depending upon local conditions. In
the Northernmost Zone, for example, the diluting effect of rainfall should be
taken into consideration.
In spite of these uncertainties, the Panel Report did conclude, we believe
reasonably, that integrated use of groundwater and canal water for irrigation
can be safely undertaken throughout most of the cultivated area in former
Punjab and Bahawalpur. Consequently, major investments to construct many
large, deep tubewells are justified. In the following sections, further justifications
for thigh conclusion are derived.
Salinity Control with Mixtures of Groundwater and Surface Water
The amount of irrigation water required to maximize crop production and
control salination depends not only upon the consumptive use by crops but
also upon the chemical quality of the water. The higher the salinity and/or the
ratio of sodium ions to calcium and magnesium ions, the more water is needed.
An extra amount, over and above the consumptive demands of the plants, must
be allowed to percolate through the root zone. This will make it possible to
maintain the concentration of salts in the soil water at a level such that growth
will be sustained and excessive sodium absorption on the clay lattices will not
occur. The critical period occurs at the end of the irrigation cycle just before
watering, when the soil moisture is low and its salt concentration is high. The
concentration at this time should be maintained at or below the tolerance level,
which depends upon the particular crop and upon the type of soil. Two para-
meters are important in achieving salinity control: i) the total depth of water
applied per crop or per year; and ii) the irrigation time, that is, the period bet-
ween waterings.








348 The Pakistan Development Review
The relations between the variables may be formulated as follows:-
Consider a soil column of unit surface area and a depth extending through
the root zone to the drainage region.
Let Wr= the weight of water in the column when the soil moisture is at
field capacity, pounds per square foot;
Wa the weight of water applied with each watering, pounds per square
foot;
E = the evapotranspiration rate, pounds per square foot per week;
T = the irrigation time (period between waterings), weeks;
Ca = the salt concentration in the applied water;
Cr = the maximum permissible concentration in the soil water. The
magnitude of Cr is fixed by the type of crop (degree of salt toler-
ance) and/or the limiting value of the sodium absorption ratio
in the soil water for the particular soil being irrigated.
A = Wa/62.4T = the irrigation rate, feet per week;
R = the leaching ratio; the quantity of drainage water as a fraction of
the amount of water applied.
After the soil has been irrigated for a period of time, the salt content in the
soil will approach an equilibrium value with the increment of salt added during
each cycle being balanced by the decrement of salt removed in drainage.
The amount of drainage water per cycle will be the excess of the water
applied over that used consumptively. The leaching ratio therefore will be
R W -- T/W > 0 ......................................................(1)
With each application the soil is saturated and drainage occurs until the soil
moisture reaches a level corresponding to field capacity. With good soils this
process occurs in a time interval that is small compared to the irrigation time.
The consumptive use during the irrigation time will be the product of this time
and the evapotranspiration rate. The water remaining in the soil at the end of
the cycle, therefore, will be,
WT, Wf-- ET >_0 ......................................................... (2)
If the system is managed so that the concentration of dissolved salts in the
critical period at the end of the cycle has risen to the maximum permissible
amount, the residual amount of salt remaining in the soil will be WrC. When
a salt balance is attained, the influx of salt will be balanced by the efflux to
drainage. If it is assumed that the proportion of salt removed will be that of
the drainage water to the total water after irrigation, then
W.,,= [a ET)/(W+WT)1 (WTCT+WaC).








Dorfman, Revelle and Thomas: Waterlogging and Salinity 349
Using Equation (2) and solving for Ca,

C, E ) (W- ET) ................................. .................(3)
a. Wf
The maximum permissible salinity of the applied water may be formulated as
Ca -R(I- P) CT ..... ................... ........ .................... .......(4)
where P =the proportion of available water used during each watering period.
Equation (3) may also be written in the form

SD,-ET/62.4 D,-ET/62.4
C .*. .....,.............. o..... ......... o.....(5
D, Df

where D, = W,/62.4 feet, and Df W,/62.4 feet, represent respectively the depth
of applied water and equivalent depth of water at field capacity.
To illustrate the use of the formulation, the following example is presented:
(1) A surface water of good quality has been used successfully to irrigate
land in accordance with a management scheme in which a depth of water of
0.65 feet is applied every four weeks to a soil in which the field capacity is 0.80
cubic feet per square foot (50 pounds per square foot). The evapotranspiration
rate is 0.15 feet per week and the maximum permissible concentration of salt
in the pore water is Cr.
From Equation (5)
0.65-0.15(4) 0.80--0.15(4) C ...........)
c .6-- 5 .- 80 Cr ..........................................
C& 060.80

Ca -0.0192 CT
(2) A tubswell field is constructed to supply additional water to increase
the acreage under cultivation. The tubewells not only increase the total water
supply, but they make possible greater flexibility in the timing of water applica-
tions. However, because of the concentration of salt and exchangeable sodium
in the groundwater, it must be mixed with surface water to protect the soil and
assure agricultural productivity equivalent to that obtained where surface water
alone is used. What will be the maximum permissible concentration in the
blended water supply in a management scheme in which the irrigation rate per
season (or per year) is increased 25 per cent and the watering period reduced
to 1.5 weeks? The value of D, will be (1.5/4) (0.65) (1.25) = 0.305 feet.
Therefore from Equation (5),
Ca 0.305= 0.15(1.5) 0.80-,0.15(1.5) CT = 0.188 Cr .......(7)
0.305 0.80








The Pakistan Development Review


Since the value of CT is the same in both schemes, it follows that salinity con-
centration in the mixture of surface and groundwater of the second scheme
can be 0.188/0.0192 = 9.8 times larger than that of the first scheme. If the sur-
face water has a concentration of 200 milligrams per litre, then the concentra-
tion of the mixed waters can be 2000 milligrams per litre, corresponding to
groundwater with a salinity of 3800 milligrams per litre mixed (or alternated
with) an equal volume of surface water. Moreover, if the relative concentrations
of sodium, calcium, magnesium, bicarbonate and carbonate are the same in the
irrigation water used in both schemes, there will be no deterioration of the soil
in the latter scheme.

In a subsequent section of this paper (see, Equation (11)) we show that the
leaching ratio and hence the value of Ca/CT may be increased by increasing
the pumping rate without affecting the other variables. It is evident from the
foregoing analysis that integration of canal and tubewell irrigation water supplies
can incorporate a large element of flexibility in salinity and alkalinity control.
Effects of Government and Private Tubewells on Salt Build-up and Drainage
The concept of a simple salt balance in a river basin was introduced a
generation ago as a didactic device to illustrate underlying principles. Some
elementary treatises on hydrology state that as an ideal a "favorable" balance
should be maintained in which the efflux of salt from a region is not less than
the influx. While this is patently desirable over a long span of time, it is far
from being a valid design criterion that should be observed at all times, parti-
cularly in the first stages of a new era of investment in water resources. In our
case a more rational criterion is to treat the vast aquifer of the northern plain
as a primary resource to speed and sustain the economic development of West
Pakistan. Hydraulic works for control of water and water quality should be
installed in a carefully programmed sequence over a period of years. The
optimal sequence may at different times entail a "favorable" salt balance in
some regions, and an "unfavorable" balance in others. Decisions of this type
can best be made using computer models for detailed simulation of project
areas.
To maintain a salt balance, part of the irrigation water must be drained away
from the region, and drainage channels must be constructed for this purpose.
Drainage structures are expensive, and it will often be economically beneficial
to postpone their construction for as long as possible. This can be accomplished
in areas where both tubewell and canal waters are used for irrigation, if the
salt is flushed out of the root zone and washed downward with recycled pumped
water, to be stored underground. With typical private tubewells, which are
usually only about 100 feet deep, the time interval before the underground







Dorfman, Revelle and Thomas. Waterlogging and Salinity 351
water becomes so salty that drainage channels must be constructed will be
relatively short, compared to the time available with typical "government"
wells, which are usually about 250 feet deep.
Under some circumstances, early construction of drainage channels will be
desirable, and in this case, when part of the irrigation water is drained off even
in the early stages of development, the rate of increase of salt content in the
underground water will be much slower than in the absence of drainage. Here
also, the rate of build-up of groundwater salinity will be much less with deep
"government" wells than with shallow private tubewells.

The following analysis, while not as versatile as the "salt-flow-model",
presented in the Panel Report, shows the relationships involved. The system
is assumed to be in a hydraulically steady state-the elevation of the watertable
remains constant and inflows and outflows are balanced (see Figure 1)-but in
an unsteady state as regards the salt content. This quantity initially may be larger
or smaller than that in a steady state. The formulation shows the final concen-
tration in the aquifer, the rate at which the system approaches salt equilibrium,
and the significant design parameters.
Let
Qc = inflow to irrigated area from canal system, acre feet per unit time;
Qr = recharge from canal leakage and other sources, acre feet per unit time;
Q% evapotranspiration rate, acre feet per unit time;
Qd = drainage flow, acre feet per unit time;
Q, = flow through tubewells, acre feet per unit time;
A = nrr2 = total area of well influence, acres or square feet; n is the
number of wells; ro is the radius of influence of a single well; and
2ro is the (approximate) well spacing, feet.
y =the proportion of total area cropped ;
yA =is the area under cultivation;
E evapotranspirationn rate, feet per unit time.
It is assumed that recharge and throughput are uniformly distributed over the
aquifer. For a hydraulic balance over the entire system
Q + Qr= Qe + Qd .................. ........................... (8)
where Qe = EyA = Enyr2 n .................................................(9)
The irrigation supply derives from the canal system and the tubewells.
The irrigation rate will be
Qe + Qvw Qd
nyr .................................................(10)







352 The Pakistan Development Review
The throughput including flow recycled from watercourse seepage will be

Qc+Q Od Enyr% 7 > 0

and the leaching ratio (see, Equation (1)) will be

Q +Qw Qd- Enyr. 0
SQ 0 .......................................... (11)
Q,+Qw -Qd
Equation (11) shows that the leaching ratio may be increased by increasing Q,
without changing any of the other variables. Accordingly, in Equation (4) an
increase in Q, will increase the maximum value of the salt concentration of the
mixed irrigation water supply. The flow in the well will include both the through-
put and recharge. The salt carried into the groundwater in the throughput of
the irrigation water and in seepage from the distribution system is assumed to
be uniformly distributed over the area. The salt initially in the aquifer is assumed
to be distributed uniformly throughout the groundwater. Under these assump-
tions and the further assumption that complete vertical mixing of the salt occurs
during the travel to the well, the salt concentration will be the same in all parts
of the groundwater and will increase everywhere at the same rate.
If the salt concentrations in the groundwater and in the canal water are
denoted by C and C. respectively, then the weight of salt entering the ground-
water during unit time will be

Co (Q. + Qr)+ C (Q Qd)
and the amount leaving will be CQw. Therefore, the rate of increase of salt in
the aquifer will be
dC
nSrh- = Cc (Q, + Qr) + C (Q, Q) CQ
dC Cc(Q + Qr) CQd
dt nS2rh ............................ (12)
where S the storage coefficient of the soil and h = effective depth of the well.
Equation (12) may be integrated to give the following time-path for the salinity
concentration in the groundwater:
C = [C, (Q, + Qr)/Qd [d1-exp (-Qdt/nSxr2 h)] +
Cg exp (-Qdt/nSxr2h)..................................(13)
where C, is the initial salt concentration of the groundwater.







Dorfman, Revelle and Thomas: Waterlogging and Salinity 353
If the rate of drainage is very small or zero, Equation (13) may be written
in the form of a linear equation in which the time rate of increase of the ground-
water salinity is constant. The time required for the concentration to reach a
specified maximum value Cm may be computed from the following equation.

SAh
t C- C](Qc Qr) (C -C g) ....................................(14)

Values of t for a range of soil salt contents from 0 to 50 tons/acre and for
well depths of 50 to 250 feet are given in Table VI. In part I of this table, the
initial salt concentration in the groundwater is taken as 500 mg/l; in part II,
it is 750 mg/1. These values were chosen in order to keep well within the range
of conditions where there is general agreement that tubewells can be used [4].
For privately operated tubewells, it will be difficult to attain an "optimum"
mixing ratio of tubewell and canal waters. Hence Cm is taken as 1500 ppm.
We have assumed that the volume of canal water plus river recharge is 3.3 acre
feet/acre/year, Co is 250 ppm, and S is 0.25.
The times given above are those required for the average salinity in the
groundwater layer which is supplying the well to reach 1500 ppm. As shown
in the Panel Report, the time required for the well water to reach this salinity
(after a brief initial period) will be somewhat longer than the above values, be
cause thorough mixing does not occur in the aquifer. But the delay due to imper-
fect mixing will be short for shallow wells, and long for deep wells.
It is clear that relatively shallow tubewells without drainage channels to
maintain a salt balance will become excessively salty in a few years, if they are
used in areas where there is a significant initial salt accumulation in the soil.
Within a few years after the tubewells are installed, channels will have to be
constructed to carry away salty groundwater. If the salty water has a salinity
of 1500 mg/l, the minimum amount of water that will need to be carried away
will be 1/6th of the total canal supply, including that which enters the ground as
recharge. Unless the conveyance channels are lined, about 25 per cent of the total
water supply will have to be run into them, to make up for leakage. But part
of this will, of course, be recovered by the wells. However, the 1/6th of the
total supply that cannot be used will reduce the gross sown acreage.
Equation (14) and Table V give the time for salt build-up before surface
drainage is installed. If soil drainage exists from the beginning, Equation (13)
applies. The ultimate concentration in the groundwater will then be Cc (Qe +
Qr )/Qd However, the time elapsed before a salt balance is attained may be
very long. For example, if C =- 250 milligrams per litre and (Qc + Qr )/Qd 8,







354 The Pakistan Development Review

then the ultimate concentration will be 2000 milligrams per litre. If Qd/n n r -=
0.25, S =0.25 and Cg = 750 mg/1 the salinity of the groundwater and the tube-
well water at various times is given in Table VII for tubewell depths of 100 and
250 feet.
"Horizontal" versus "Vertical" Drainage
Any drainage system in an irrigated area must serve two purposes: i) removal
of excess water and control of the elevation of the watertable; ii) removal of
saline water to prevent accumulation of salt in the soil. These objectives can
be accomplished in one of two ways: i) by pumping water from underground
and carrying part of the pumped water away from the region in conveyance
channels; or, ii) by allowing part of the irrigation water to percolate into a
series of small ditches or porous tile pipes, which lead into larger "collector"
and "main" drains. Such a "horizontal" system can be used to remove saline
waters only if the watertable is sufficiently close to the surface to prevent a
major part of the irrigation return flows from seeping out of the drains. The
system is not effective for salinity control in a region where both ground and
surface waters are being used for irrigation and the watertable is pumped down
significantly below the bottom level of the drainage channels during part of the
time. Wherever large numbers oftubewells, either public or private, are employed
to supply part of the irrigation water, it will often be undesirable to keep the
watertable high. Horizontal drainage structures will then have a limited useful-
ness, primarily to carry off flood waters.. In regions of highly saline under-
ground water, tubewells will not be employed to provide irrigation supplies,
and either a horizontal system or a system of tubewells plus conveyance channels
can be employed for drainage. Several factors should enter into the choice
between these alternatives.

Horizontal drainage may be economical in certain regions of West Pakistan,
particularly in parts of the Southern Zone, where conditions for vertical drain-
age are not satisfactory. In the Panel Report, however, we concluded that
vertical drainage would be desirable in most areas of the Indus Plain.

The principal disadvantage of horizontal drainage is that it must operate
with a relatively high watertable, and hence is incompatible with the use of tube-
wells to increase and stabilize the irrigation water supply. But other disadvant-
ages must also be kept in mind.

1) A system of main drains and tile or open field drains is essentially a passive
system. It is dependent upon gravity flow and once it is constructed it cannot
easily be modified or revamped. The amount of water discharged through such
a system depends upon the amount of water applied to the land it subtends,
and the salt removed in drainage depends largely upon the salinity of the upper








Dorfman, Revelle and Thomas: Waterlogging and Salinity 355
layers of the groundwater. The flow in the main drains and laterals depends
on seepage rates and these in turn depend upon the gradient of the watertable.
A vertical drainage system, on the other hand, is more flexible. The flow and
sr.linity of the mixed effluent of a set of tubewells can be controlled, and conse-
quently, drainage can be carried out at any desired rate. This results both in a
smaller investment in conveyance channels and in better salinity control, because
salt can be returned to the rivers during periods of high runoff, or routed to salt
lagoons at times when the irrigation requirement is small.
Compared with vertical drainage, horizontal drainage systems are wasteful
of water. The salinity concentration of the drained water is likely to be smaller
than with tubewell drainage and hence larger amounts of water must be carried
away in the drains.
2) In flat topography it is difficult to fit together efficiently a horizontal
drainage system with an intensive irrigation system. Crossings of conveyance
lines of the two systems are unavoidable and are expensive. If the drainage
is to be returned to the canals, pumps are required. The principal costs of
horizontal drainage in the Indus Plain would be associated with pumps and
with concrete control and access structures including weirs, gates, check stops,
bridges and pump sumps that cannot be built with unskilled labor.

3) Irrigated agriculture is most successful when it is most intensive, that is
when it is concentrated on a minimum land area. Open drain systems occupy a
significant portion of the land area in and between the cultivated fields and
hence cause the farming operations to be spread out on more land. While it is
true that the supply of good land is greater than the supply of water throughout
most of the Indus Plain, the layout of an extensive horizontal drainage system,
which must conform to the topography and have a minimum number of inter
sections with the distribution system, will extend and complicate the access
routes to the fields. Farming operations are impeded when bridges must be
crossed.
4) Deep main drains and open field drains are difficult to maintain. Drain-
age works are sporadically impaired by flood damage and their efficiency is
regularly reduced by growth of weeds. Flood damage to drains is inherently more
serious than the damage to water distribution channels because of topography.
Unless pumps are used, artificial drainage must conform with natural drainage.
Consequently the drains must be adequate to handle storm runoff and must be
repaired after the floods recede. Weed growth in drainage ditches is more abun-
dant than in distribution channels because of lower flow velocity and greater
nutrient supply. Maintenance of drains-removal of weeds and debris, channel
realignment and repair of side slopes-is difficult and unpleasant work. Even a
cow does not like to descend into the weedy morass of a malfunctioning drain.








356 The Pakistan Development Review
5) In semi-tropical climate the stagnant water and swampy reaches of open
drains may constitute a public health hazard. The ditches afford a favorable
environment for the growth of mosquitoes and snails. In other countries endemic
and epidemic levels of morbidity from malaria and bilharziasis have been caused
by horizontal drainage works that have not been properly maintained.
A Comment on Sub-irrigation
One of the arguments for a horizontal drainage system is that by keeping
the watertable close to the surface a considerable fraction of the seepage from
canals and water courses can be recovered by the crops through sub irrigation.
In the historical development of most irrigation projects it commonly
happens that at one time or another enthusiasm is generated over the possibi-
lities of sub-irrigation as a cheap method of water distribution. When such
schemes are tried, however, they are usually found to have serious limitations.
In some cases they have failed completely and caused serious land damage. In
the United States, there have been two exceptions where sub-irrigation has
proved to be more than a fad. One of these is in the San Luis Valley in Colorado,
and the other in the Snake River Basin in Idaho. In both of these places the
following favorable conditions obtain:
i) the slopes of the land and watertable are relatively steep so that stagna-
tion does not occur; and
ii) the soil and subsoil are permeable (in the San Luis project the soil is
almost a fine gravel, in Idaho the aquifer is a coarse-textured volcanic ash).
Sub-irrigation at these sites has worked because it is possible to drain the soil
thoroughly during the non-irrigation season. The soil is recharged in the spring;
after the harvest the watertable is lowered and the salt carried away.
We conclude that sub-irrigation, as well as conventional horizontal drainage,
might find limited application in certain localities of West Pakistan under
special geological and hydrological conditions. Neither of these methods warrant
much attention, however, in the primary scheme of water resource develop-
ment in the Indus Plain.
CONCLUDING REMARKS
Agricultural production has shown heartening progress in the past two
or three years, particularly in regions where traditional supplies of irrigation
water have been enhanced either by government tubewells, as in SCARP I, or
by private tubewells as in the upper part of Rechna Doab. Farmers have taken
advantage of the improved water supplies with admirable alacrity. The trends
in crop yields per acre and particularly in the intensity of cultivation both reflect








356 The Pakistan Development Review
5) In semi-tropical climate the stagnant water and swampy reaches of open
drains may constitute a public health hazard. The ditches afford a favorable
environment for the growth of mosquitoes and snails. In other countries endemic
and epidemic levels of morbidity from malaria and bilharziasis have been caused
by horizontal drainage works that have not been properly maintained.
A Comment on Sub-irrigation
One of the arguments for a horizontal drainage system is that by keeping
the watertable close to the surface a considerable fraction of the seepage from
canals and water courses can be recovered by the crops through sub irrigation.
In the historical development of most irrigation projects it commonly
happens that at one time or another enthusiasm is generated over the possibi-
lities of sub-irrigation as a cheap method of water distribution. When such
schemes are tried, however, they are usually found to have serious limitations.
In some cases they have failed completely and caused serious land damage. In
the United States, there have been two exceptions where sub-irrigation has
proved to be more than a fad. One of these is in the San Luis Valley in Colorado,
and the other in the Snake River Basin in Idaho. In both of these places the
following favorable conditions obtain:
i) the slopes of the land and watertable are relatively steep so that stagna-
tion does not occur; and
ii) the soil and subsoil are permeable (in the San Luis project the soil is
almost a fine gravel, in Idaho the aquifer is a coarse-textured volcanic ash).
Sub-irrigation at these sites has worked because it is possible to drain the soil
thoroughly during the non-irrigation season. The soil is recharged in the spring;
after the harvest the watertable is lowered and the salt carried away.
We conclude that sub-irrigation, as well as conventional horizontal drainage,
might find limited application in certain localities of West Pakistan under
special geological and hydrological conditions. Neither of these methods warrant
much attention, however, in the primary scheme of water resource develop-
ment in the Indus Plain.
CONCLUDING REMARKS
Agricultural production has shown heartening progress in the past two
or three years, particularly in regions where traditional supplies of irrigation
water have been enhanced either by government tubewells, as in SCARP I, or
by private tubewells as in the upper part of Rechna Doab. Farmers have taken
advantage of the improved water supplies with admirable alacrity. The trends
in crop yields per acre and particularly in the intensity of cultivation both reflect








Dorfman, Revelle and Thomas: Waterlogging and Salinity 357
this. There is every reason to expect that with the opening of new SCARPS
and with the continued spread of private tubewells this progress will persist
Nevertheless we must reiterate that insufficient water was not the only deficiency
in the Indus Plain and the provision of more water is not the solution to the
agricultural problem there. It is only the first step and, we hope, the catalyzing
step in a movement toward thorough-going agricultural modernization. We do
not have to spell out again the other measures that are urgently demanded; the
report of the Commission on Food and Agriculture and our previous Report
have covered these measures in ample detail. We need here only state our im-
pression that insufficient attention is being given to the other needs of agri-
culture in West Pakistan. Unless these other needs are met the ultimate results
of all this effort will be disappointing. Yields will remain below world-wide
averages, the ravages of insect and rodent pests will continue, and agricultural
incomes will not advance as they should and must. The progress in the fields
of agricultural extension, agricultural credit, seedstock improvement, and other
directions has not been comparable to the progress made in improvements in
water supply and in the use of fertilizer. We should like to conclude our review
with an earnest plea that vigorous attention to these problems, admittedly
difficult, be given the highest priority.

REFERENCES
1. White House-Department of Interior Panel on Waterlogging and
Salinity in West Pakistan, Report on Land and Water Development in
the Indus Plain: (Washington, D.C.: The White House, January 1964).
2. Harza Engineering Company International, Programme for Water and
Power Development in West Pakistan through 1975. (Lahore: West
Pakistan Water and Power Development Authority, January 1964).
3. Harza Engineering Company International, A Programme for Water
and Power Development in West Pakistan 1963-75. Supporting Studies. An
Appraisal ofResources and Potential Development. Chapter II: (Lahore:
Summer 1963)
4. Ghulam Mohammad, "Waterlogging and Salinity in the Indus Plain:
A Critical Analysis of Some of the Major Conclusions of the Revelle
Report", Pakistan Development Review, Vol. IV, No. 3, Autumn 1964.
5. Ghulam Mohammad, "Private Tubewell Development and Cropp-
ing Patterns in West Pakistan", Pakistan Development Review, Vol. V,
No.l, Spring 1965.








358 The Pakistan Development Review
6. Harza Engineering Company International, Reconnaissance Survey
of Private Tubewells. (Lahore: February 1965).
7. Ghulam Mohammad, "Some Strategic Problems in Agricultural Deve-
lopment in Pakistan", Pakistan Development Review, Vol. IV, No. 2,
Summer 1964.

8. Bower, C. A. and M. Maasland, "Sodium Hazard of Punjab Ground-
waters", Symposium on Waterlogging and Salinity in West Pakistan.
(Lahore: West Pakistan Engineering Congress, October 1963).
9. Maasland, M. J. E. Priest and M. S. Malik, "Development of Ground
Water in the Indus Plains", Symposium on Waterlogging and Salinity in
West Pakistan. (Lahore: West Pakistan Engineering Congress, October
1963).









Dorfman, Revelle and Thomas: Waterlogging and Salinity

TABLE 1

HARZA "PROGRAMME" IRRIGATION WATER BUDGET
PART I: REQUIREMENTS


Northern Southern Indus
Zone Zone Plain


A. Assumed cultivated area (million acres)

1. Net cultivated area1

2. Gross sown area

a. Rabi

b. Kharif

c. Total

B. Irrigation water requirement (million acre-feet)

1. At water courses3

a. Rabi

b. Kharif

c. Annual

2. Beneficial use on fields (Evapotranspiration by
crops plus leaching)4

a. Rabi

b. Kharif

c. Annual

C. Depth of water used beneficially on fields (feet)

a. Rabis

b. Kharifs

c. Annual


19.4



17.5

11.6

29.1





36

46

82




28

35

63


7.0 26.4


2.6

4.9

7.5





9

17

26




7

13

20


20.1

16.5

36.6





45

63

108




35

48

83


1.6 2.7 1.7

3.0 2.7 2.9

3.2 2.9 3.1


Source: Computed from data and assumptions in [3].
1 From [3, Table 11-7].
2 Computed from cropping patterns in [3, Tables II-9 and II-10].
3 Computed from [3, Tables II-11 and 11-12].
4 Values in B.1 multiplied by .765 (see text).
5 Values in B.2.a and B.2.b divided by corresponding values in A.2.a and A.2.b.
6 Values in B.2.c. divided by corresponding values in A.I.








360 The Pakistan Development Review

TABLE I (contd.)
HARZA "PROGRAMME" IRRIGATION WATER BUDGET

PART II : SUPPLIES


Northern Southern Total
Northern SIndus
Zone Zone Plain

A. From river diversions (million acre-feet)

1. At canal heads1

a. Rabi 20 13 33

b. Kharif 46 24 70

c. Annual 66 37 103

2. At water courses

a. Rabi 14** 9t 23tt
b. Kharif 32** 17t 49tt

c. Annual 46** 26t 72*

B. From tubewells, at water courses (million acre-feet)2
a. Rabi 22 -22
b. harif 14 14

c. Annual 36*t 36*f
C. Total supplies at water courses (million acre-feet)t

a. Rabi 36 9 45

b. Kharif 46 17 63

c. Annual 82 26 108*t
1 Values at water courses (see A.2.), divided by 0.7.
2 Values in A.2 subtracted from corresponding values in C.
64.3 MAF [2, p. 28] plus 8 MAF [2, p. 29].
( From Part I: Requirements, values in B.1.
ff From Table II.
** Total diversions for Indus Plain-diversions for Southern Zone.
*t [2, pp. 28.30]. 64.3 MAF average diversions at water courses with present canal system
must be supplemented by 44 MAF to meet irrigation requirements. Of this amount, 8 MAF
can be obtained by enlarging canals, the remainder can be provided by groundwater pumping
and additional reservoirs.









Dorfman, Revelle and Thomas Waterlogging and Salinity 361

TABLE II

POSSIBLE AVERAGE MONTHLY WATER BUDGET IN THE INDUS PLAIN
BASED ON HARZA "PROGRAMME" WITH PRESENTLY DESIGNED SURFACE
STORAGE AND ASSUMED TUBEWELL AND CANAL CAPACITIES*


Month



(1)


October
November
December
January
February
March
Rabi total

April
May
June
July
August
September
Khariftotal
Annual values


River and
At water courses At canal heads reservoir losses
Supplies
Irri- --- Total River Changes Seepage
gation diver- flows in and eva- To sea
require- from from sions surface portion
ments canals wells storage
(2) (3) (4) (5) (6) (7) (8) (9)

(..............million acre-feet**.............)
11.1 6.4 4.7 9.1 4.6 -4.6 0.1 0.0
7.0 3.0 4.0 4.3 3.1 -1.3 0.1 0.0
5.3 3.0 2.3 4.3 2.6 -1.8 0.1 0.0
7.0 3.0 4.0 4.3 2.7 -1.7 0.1 0.0
5.6 3.1 2.5 4.4 2.9 -1.6 0.1 0.0
8.8 4.1 4.7 5.8 5.0 -0.9 0.1 0.0


44.8 22.6 22.2 32.2 20.9 -11.9 0.6 -

7.4 5.7 1.7 8.1 8.2 0.0 0.1 0.0
12.9 8.7 4.2 12.4 14.2 0.0 02 1.6
13.4 8.7 4.7 12.4 22.4 0.0 3.0 7.4
10.7 8.7 2.0 12.4 30.7 +7.3 4.0 7.0
10.5 8.7 1.8 12.4 26.8 +4.7 4.0 5.7
8.7 8.7 0.0 12.4 12.4 -0.1 0.1 0.0
63.6 49.2 14.4 70.1 114.7 +11.9 11.4 21.7
108.4 71.8 36.6 102.3 135.6 0.0 12.0 21.7


Assumptions: Live storage back of Mangla and Tarbela Dams = 12.0 MAF
Canal capacity-12.4 MAF/month=207,000 second feet
Tubewell capacity > 4.7 MAP/month = 78,000 second feet.
Annual losses from seepage and evaporation in rivers and reservoirs
= 12.0 MAF [Harza, p. 29] states that 12 MAF are lost in natural
river channels between the rim stations and diversion points.
** Differences between corresponding values in Tables 1 and 2 are due to
rounding.
Sources: Col. (2): Computed from [3, Tables II-11 and II-12], combined with acreages
and intensities of cultivation given in [3, Tables 11-7, 11-8 and II-9];
see also our Table I. (sources continued on next page)









The Pakistan Development Review

Col. (3): Column (5) x 0.7.
Col. (4): Column (2) Column (3).
Col. (5): Maximum monthly canal diversions during kharif are limited by the
assumed canal capacity of 12.4 MAF/month. Average monthly diver-
sions during rabi are limited by the volume of water available in river
flows plus surface storage; as Column (5) shows, this average is 5.4
MAF/month. With this limitation, the maximum monthly diversion
during rabi is determined by the maximum difference between tubewell
capacity and the irrigation requirement in any month. To minimize
investment costs we have assumed that tubewell capacity is set by the
amount of pumping needed in June-the month of highest irrigation
requirement. This results in computed diversions of 9.1 MAF in
October and only 4.3 MAF/month during November through January.
Unless some canals are effectively non-perennial, the ratio between
maximum and minimum canal flows of 12.4 to 4.3 may be too high to
avoid difficulties of silting and erosion, and of inadequate check struc-
tures for gravity flow to water courses. These difficulties may exist even
with a kharif-rabi ratio of 12.4/5.4
Col. (6): From [1, Table 1.2 and Figure 7.1].
Col. (7): Column (6)-[Column (5) + Column (8) + Column (9)].
Col. (8): River and reservoir losses from September through May are assumed
to be principally by evapotranspiration. During June through August,
evapotranspiration is greatly increased because of the spreading of the
rivers in flood; in addition, there are major seepage losses during these
months.
Col. (9): It may be possible to capture part of the runoff shown in this column
through recharge of groundwater in the Southern Zone, provided
additional tubewells are installed to pump out the aquifer near the
Indus banks during the months of low flow.









Dorfman, Revelle and Thomas: Waterlogging and Salinity 363

TABLE III

COMPARISON OF AVERAGE ANNUAL IRRIGATION BUDGETS

Harza Ghulam
"Programme" Panel Mohammed
(1) (2) (3)

A. Cultivated area (million acres)

1. Net cultivated area

a. Northern Zone 19.4 17.05 15.8

b. Southern Zone 7.0 9.56 n.g.7

c. Total, Indus Plain 26.4 26.5 n.g.

2. Gross sown area

a. Northern Zone 29.1 28.4 20.7

b. Southern Zone 7.5 12.8 n.g.

c. Total, Indus Plain 36.6 41.2 n.g.

B. Cropping intensities (in per cent)9

a. Northern Zone 15010 167 13111

b. Southern Zone 10712 13513 n.g.

c. Indus Plain 139 159 n.g.

C. Irrigation water supplies (million acre-feet)

1. Diversions at canal heads

a. Northern Zone 66 4814 61

b. Southern Zone 37 44 n.g.

c. Total, Indus Plain 103 92 n.g.

2. Canal supplies at water courses
a. Northern Zone 46 3015 4316

b. Southern Zone 26 3817 n.g.

c. Total, Indus Plain 72 68 n.g.

3. Tubewell supplies at water courses

a. Northern Zone 36 4718 1619

b. Southern Zone 0 1120 n.g.

c. Total, Indus Plain 36 58 n.g.
--- -------------- -(continued)-









364 The Pakistan Development Review

TABLE III (contd.)

Harza Ghulam
"Programme" Panel Mohammed
(1) (2) (3)

4. Total supplies at water courses
a. Northern Zone 82 77 59
b. Southern Zone 26 49 n.g.
c. Total, Indus Plain 108 126 n.g.
5. Beneficial uses on fields: crop evapo-
transpiration plus leaching
a. Northern Zone 63 6122 4521
b. Southern Zone 20 3623 n.g.
c. Total, Indus Plain 83 97 n.g.
D. Annual depth of water used beneficially (feet)24
1. On net cultivated area
a. Northern Zone 3.2 3.6 2.8
b. Southern Zone 2.9 3.7 n.g.
c. Indus Plain 3.1 3.7 n.g.
2. On gross sown area
a. Northern Zone 2.2 2.2 2.2
b. Southern Zone 2.7 2.7 n.g.
c. Indus Plain 2.3 2.3 n.g.
E. Water losses from canals, water courses and
fields (million acre-feet)
1. Total seepage25
a. Northern Zone 29 2426 24
b. Southern Zone 14 1327 n.g
c. Total, Indus Plain 43 37 n.g.
2. Non-beneficial evapotranspiration28
a. Northern Zone 15 1029 12
b. Southern Zone 6 730 n.g.
c. Total, Indus Plain 21 17 n.g.
-- ---(continued)-









Dorfman, Revelle and Thomas: Waterlogging and Salinity 365

Sources: Col. (1) From Table I.

Col. (2) From data and computations in [1, Chapters 5 and 7, pp. 192-
193 and 269-284].

Col. (3): From [4, pp. 381-383].

4 Canal commanded area planted at least once during the year plus
fallow.

5 In the Panel Report, the net cultivated acreage for the former Punjab
and Bahawalpur is given as 16.4 MA, corresponding to "firm" canal
diversions (4 out of 5 years) of 45 MAF. For comparison with Harza
and Ghulam Mohammad we have used the Panel's average diversion
of 48 MAF, which gives an increase of 3 per cent in the volume of
water for beneficial use on crops. The net cultivated acreage is increased
accordingly.

6 Mean of range of 8 to 11 MA.

7 n.g. = not given.

8 Gross sown area= Net cultivated area x per cent cropping intensity/100.

9 In computing cropping intensity, Harza counts the acreage planted to
sugarcane during both kharifand rabi: in the Panel Report, the sugar
acreage is counted only once, in kharif. Here we have used the Harza
procedure.

10 60 per cent in kharifand 90 per cent in rabi.

11 Per cent cropping intensity chosen to give same depth of water for
beneficial use on the gross sown area (2.2 ft.) as in Column (1).
12 80 per cent in non-perennial area and 135 per cent in perennial area.

1i Per cent cropping intensity chosen to give same depth of water for
beneficial use on gross sown area (2.7 feet) as in Column (1).

14 Average canal diversions to former Punjab and Bahawalpur.

is Seepage and non-beneficial evapotranspiration in canals are assumed
to be 26 per cent and 12 per cent of canal head diversions, respectively.

16 Seepage and non-beneficial evapotranspiration in canals are assumed
to be 24 per cent and 6 per cent of canal head diversions, respectively,
following Harza.

17 Combined seepage and non-beneficial evapotranspiration in canals
is assumed to be 13 per cent of canal head diversions.

18 41 MAF in the Panel's "non saline" area plus 6 MAF in the "saline"
area.









366 The Pakistan Development Review

19 12 MAF from canals, water courses and field seepage in Ghulam
Mohammad's "non-saline area" and 4 MAF from "recharge from
rain and river".

20 Total pumping at water courses required to provide 8 MAF of well
water for beneficial use on farm fields (8/(1-.26) = 11 MAF).

21 Supplies at water courses-10 per cent losses in water courses and
15 per cent non-beneficial seepage plus evapotranspiration of water
applied to fields. (.765 x water course supplies).

22 Supplies at water courses-20 per cent losses in water courses and
farm fields.

23 Supplies at water courses-26 per cent losses in water courses and
farm fields.

24 Beneficial use = evapotranspiration from crops or cultivated fields
plus water required for leaching.

25 Except for Column (3), total seepage is assumed to be 37 per cent of
diversions at canal heads plus 14 per cent of water pumped from tube-
wells.

26 35 per cent of diversions at canal heads plus 15 per cent of water pumped
from tubewells.

27 26 per cent of diversions at canal heads plus 17 per cent of water pumped
from tubewells.

28 Except for Column (3) non-beneficial evapotranspiration is assumed
to be 16 per cent of diversions at canal heads plus 14 per cent of water
pumped from tubewells.

29 15 per cent of diversions at canal headsplus 5 per cent of water pumped
from tubewells.

30 13 per cent of canal head diversions plus 9 per cent of water pumped
from tubewells.









Dorfman, Revelle and Thomas: Waterlogging and Salinity 367

TABLE IV

COSTS OF WATER USING GOVERNMENT AND PRIVATE TUBEWELLS

(A) (B)
Item Government Private
tubewells tubewells


1. Direct construction cost (rupees) 51900 7800

2. Water distribution system and land (rupees) 3140 -

3. Net construction cost 47760 7800

4. Annual amortization factor (at 6 per cent) .0872 .1359

5. Annual charge (rupees) 4165 1060

6. Rate of flow (cusec) 3.9 1.25

7. Output per year. (2200 operating hours) (acre feet) 710 227

8. Capital charge per acre foot (rupees) 5.88 4.67

9. Operating cost per day (rupees) 11.06

10. Output per day, (acre feet) 0.826

11. Operating cost per acre foot (rupees) 10.80 13.38

12. Total cost per acre foot (rupees) 16.68 18.05

Sources: Rows 1, 2: [7, Table B-I].
Rows 3, 4, 5: Computed. 20-year economic life assumed for government
tubewells, 10 years for private tubewells.
Row 6: (7, Table B-I].
Rows 7, 8: Computed.
Row 9: [7, Table B-II].
Row 10: Computed.
Row 11: (A) from [1, Table 7.4, adjusted to power cost of Rs. 0.08 per Kw.hr].
(B) Computed.
Row 12: Row 8 + Row 17.











TABLE V
SALINITY OF GROUNDWATER IN NORTHERN ZONE
Area underlain by groundwater of indicated salinity

Former Punjab2 Former Bahawalpur3

Canal Non-canal Canal Non-canal
regions regions4 regions regions


Total

Canal Non-canal
regions regions


Less than 500 ppm
500-1000 ppm
1000-2000 ppm
2000-3000 ppm
3000-4000 ppm
4000-5000 ppm
5000-10,000 ppm
10,000-20,000 ppm
More than 20,000 ppm
Total gross area
Culturable commanded area

Less than 500 ppm
500-1000 ppm
1000-2000 ppm
2000-3000 ppm
3000-4000 ppm
4000-5000 ppm
5000-10,000 ppm
10,000-20,000 ppm
More than 20,000 ppm


(.............................................million acres................................................ )
9.9 0.1 1.2 11.1 0.1 11.2
6.4 2.8 0.8 7.2 2.8 10.0
3.4 0.71
1.2 0.3 ) 1.1 0.4 7.0 1.5 8.5
0.6 0.lJ
0.7


1.0 1.3 0.7 2.3 0.7 3.0
0.2 0.6 0.4 0.8 0.4 1.2
0.1 0.1 0.1
23.4 4.0 5.1 1.5 28.5 5.5 34.0
15.2 3.5 18.7 18.7
(............................................. Per cent of gross area........................................ ... )
29.2 0.3 3.5 32.7 0.3 33.0
18.8 8.2 2.4 21.2 8.2 29.4
10.0 2.1)
3.5 0.9 3.2 1.2 20.6 4.5 25.1
1.8 0.31
2.1 -_
2.9 3.8 2.0 6.7 2.0 8.7
0.6 1.8 1.2 2.4 1.2 3.6
0.3 0.3 0.3


4.4 83.9


16.2 100.1


Source: From [3, Table 11-5, Chapter II. Irrigation Development in the Indus Plain].
1 Salinity as parts per million of total dissolved solids in groundwater samples at a depth of more than 100 feet.
2 Includes Thai, Chaj, Rechna and BariDoabs, but not Indus Right Bank areas.
3 Areas under command of Fordwah, Eastern Sadiquia, Quimpar, Bahaw canals, Plus 1.5 MA of "undeveloped" area
4 Includes 1.7 million acres in Gujrat Plain and Sialkot, where well irrigation is used, and 2.4 million acres of undeveloped and
desert area in Thal Doab.
5 2.0 million acres commanded by the Panjnad Canal has been incompletely surveyed. According to Harza, about 50 per cent of this
area is believed underlain by water with less than 1000 ppm of salinity. Accordingly, we have distributed the Panjnad Canal area as
follows : 0.5 million acres less than 500 ppm; 0.5 million acres, 500-1000 ppm; 0.3 million acres, 1000- 5000 ppm; 0.4 million acres,
5000-10000 ppm; 0.3 million acres; 10000-20000 ppm.


Salinity


Total


_ ~1~__~1~~_


_~_~~


_I________________C_____________ ~_









Dorfman, Revelle and Thomas: Waterlogging and Salinity 369
TABLE VI
TIME OF BUILD-UP OF SALINITY IN UNDERGROUND WATER FOR
TUBEWELLS OF DIFFERENT DEPTH

I. INITIAL GROUNDWATER SALINITY=500 PPM
FINAL GROUNDWATER SALINITY=1500 PPM

Well Soil salt, tons/acre 0 10 20 30 40 50
depth
Feet Time in years to reach 1500 ppm in groundwater

50 15.1 6.3 0 0 0 0
100 30.2 21.4 12.5 3.7 0 0
150 45.5 36.7 27.8 18.9 10.0 1.1
200 60.5 51.6 42.7 33.8 25.1 16.0
250 75.6 66.9 57.9 48.4 40.6 48.4

II. INITIAL GROUNDWATER SALINITY =750 PPM
FINAL GROUNDWATER SALINITY = 1500 PPM

Well Soil salt, tons/acre 0 10 20 30 40 50
depth
Feet Time in years to reach 1500 ppm in groundwater

50 11.3 2.5 0 0 0 0
100 22.7 13.8 5.0 0 0 0
150 34.1 25.2 16.4 7.5 0 0
200 45.4 36.4 27.6 18.7 10.0 0.9
250 56.7 48.0 39.2 30.4 21.6 12.5




TABLE VII
SALINITY OF TUBEWELL WATER AT DIFFERENT TIMES, WHEN
DRAINAGE SYSTEM IS INSTALLED AT THE BEGINNING
OF PUMPING


Time in years 0 10 20 40 50 100 200 250
Salinity, ppm

Well depth, 100 feet 750 870 975 1165 1230 1540 1830 1895
Well depth, 250 feet 750 800 850 935 975 1165 1435 1540







The Pakistan Development Review













Waterlogging and Salinity in the

Indus Plain: Comment

by
NAZIR AHMAD*

Mr. Ghulam Mohammad, Senior Research Economist of the Pakistan
Institute of Development Economics, by publishing his critical analysis of the
Revelle Report in Volume IV, No. 3 of the Pakistan Development Review [4]
has done a great service to the country. A chance has, thus, been created to exa-
mine some of the recommendations for the solution of the problem as put forth
by the Panel of scientists from America.
Ghulam Mohammad has summarised the major recommendations of the
Revelle Report and then commented upon these, giving alternative sugges-
tions. The main recommendations of the report are to install tubewells in the
large agricultural regions of the Indus Plain. This suggestion is to supple-
ment the insufficient diversion of the surface water and at the same time to
effect the drainage of the land. Ghulam Mohammad has discussed the
results of the quality of groundwater, and has concluded, "that groundwater
of the Indus Plain are charged with dangerous limits of bicarbonates and
sodium contents and their indiscriminate utilization will make the soils alkaline
and impermeable." In his opinion, tubewells should not be installed in areas
where concentration of sodium or bicarbonates is very high.
Ghulam Mohammad has further put forth the financial workability
of the deep open main drains combined with the open or tile field drains. As
for water economy on drained land, the author is in favour of keeping a high
level of groundwater to meet with a certain amount of crop requirements from
sub-irrigation.
Ghulam Mohammad has cautioned against the indiscriminate use of
groundwater on the land. At present, according to the Panel of scientists,
the main problem is the insufficiency of water for sustained agriculture and
lack of proper utilization of agricultural practices. For finding more water
and to effect quick drainage, tubewells are suggested and for improvement

*Dr. Nazir Ahmad is the Principal Research Officer (physics) at the Irrigation Research
Institute, Lahore.








72 The Pakistan Development Review

of agricultural yield, better management, better seeds, use of fertilizer, pest
control, use of insecticide and such other measure, known to increase the yield,
are suggested. The Panel has laid great stress on the agricultural aspect of the
problem. Very little consideration is given to other means of drainage, on
chemistry of soil and water and other hydrological and engineering considera-
tions. Installation of tubewells, mining of accumulated groundwater, disposal
ofs aline groundwater, salinity build-up in the aquifer, spacing of tubewells,
etc., are the points discussed at length in the report. The points missed are the
long term success of this measure with respect to the type and design of tube-
wells, their life and durability, their working cost and results of mining on
water requirements of crops, effect of pumping saline water and its disposal, inter-
action of the quality of pumped water with the type of soils generally in existence,
etc.
Tubewells have Uneconomical Durability
This country has had more than fifty years' experience of installingtubewells
in fine to medium sand formation of the Indus Plain which contains some
small percentages of fines, such as silt and clay. Inspite of trials of many alter-
natives to develop a long-lasting tubewell, giving high economical yield, the
solution has yet baffled success. Checking of strainers and their incrustation is a
majorproblem. Iron strainers have short lives in the soil and waterof this Plain;
strainers of inert materials like cadmium, brass and copper were all tried and
found to get incrusted. Trials with inert materials like wood, and coir string also
did not stop the incrustation. Recent suggestions have been to install large dia-
meter tubewells and use strainers with wide slits. This was tried with iron and
brass strainers without much success. In case of SCARP 1, tubewells were in-
stalled with all precautions but these have started to misbehave in a short
period of four years.
It was suggested that for an economical performance, high discharge capa-
city tubewell units may be installed. This brought in the use of turbine pumps
replacing the centrifugal pumps of I to 2 cusecs capacity. The life of components
of a turbine pump, however, is lower than a centrifugal pump (see, Table I)
and components of a turbine pump are difficult to procure.
TABLE I
Estimated
Item useful life
Well and casing 20 years
Pump turbine bowl (about 50 per cent of cost of pump unit) 8 years
Column, etc. 16 years
Pump, centrifugal 16 years
Electric motor 25 years
Diesel engine 14 years

Source: [5].








Ahmad: Waterlogging and Salinity: Comment 373

This nullified the advantages of this suggestion. Pumping a high order
discharge has some other serious disadvantages of quick incrustation, due to
the movement of fine formation. The farmers in West Pakistan have found a
solution to the incrustation. The solution is the low cost tubewells and their
frequent replacement. A farmer's tubewell, to pump one to two cusecs, hardly
costs one or two thousand dollars, so that within the life expectancy of the
tubswells (assumed ten years), they not only recover the full capital invested
within one or two years, but also make tremendous profits out of agricultural
produce due to the large amount of available water. So far, the farmers do not
know the advantages of multiple strainer tubewells. If they adopt this device
by adding three or four strainers, 100 to 150 feet in length, 50 to 80 feet.
apart, they can pump a high order discharge, even upto 3 or 4 cusecs and, at the
same time they can prolong the life of the tubewells. Such a technique of multiple
strainers has many other advantages not possible with a single strainer, turbine-
fitted tubewells. In Table II, pumping from multiple strainer tubewells with
respect to power input and discharge is shown. In these tests, the pump capacity
was only 2 cusecs and the strainers were very shallow, hardly 50 feet long with,
30 feet of blind pipe and were pumping from very fine sand (mean diameter
0.18 mm.). A longer strainer, installed in medium sand, worked by high capacity
centrifugal pump, could yield a higher order of discharge.

TABLE II
Specific yield in
Depression Discharge, Power in
Strainer head in feet in cfs/per cfs/foot gpm/foot kwh
gallon
Niazbeg test
Single 21.50 0.98/441 0.045 20.2 7.50
Double 15.00 1.48/666 0.100 45.0 9.25
Triple 17.24 1.64/760 0.100 45.0. 9.40
Niazbeg
Single 21.20 1.43/653 0.068. 30.6 8.90
Double 18.97 1.73/778 0.091 41.0 9.50
Triple 16.13 1.80/810 0.111 50.0 8.80
Kohali Distributary
Single 19.60 1.10/495 0.060 27.0 8.20
Double 17.25 1.58/711 0.087 39.1 8.84
Triple 17.48 1.70/765 0.100 45.0 9.05
Lahore Branch
Single 17.00 1.28/576 0.075 33.8 8.02
Double 15.00 1.72/774 0.112 50.4 9.20

Low Order Storage Coefficient of the Indus Formation
The Revelle Panel based their estimate of mining of groundwater on a
high order of storage coefficient. Although extensive boring results were available
which clearly showed the existence of clay lenses and existence of silty sand, yet








374 The Pakistan Development Review

while estimating the yield of groundwater, a storage coefficient for a high yield-
ing sand formation was assumed. It was pointed out [11 to the Panel on
the receipt of the first draft report in September 1962 that the storage coefficient
assumed at 25 per cent should be reduced by half as within a depth of 100 feet
from surface the soil crust and clay lenses constitute about 40 to 50 per cent
of the formation, but the Panel scientists used 25 per cent as storage coefficient
which gave higher results. The tubewells of SCARP 1 have demonstrated the
fallacy of this assumption. The fall in the level of the watertable was found to
be too quick when pumping the tubewells to their full capacity.

The Panal has assumed the total infiltration from the Punjab and Bahawal-
pur area as 20 million acre feet. The total amount of loss of water according
to the Panel is 50 per cent of that released at the head. The seepage from
canal and links is 35 per cent, the remaining 15 per cent being the evaporation
and other losses.

Earlier estimate of Kennedy, Benton and Blench are shown in Table III
below:
TABLE III
WATER LOSSES FROM CANAL DISTRIBUTION SYSTEM IN THE PUNJAB

Kennedy Benton Blench Khunger


Main canals 5 5 Seepage only
Branches 15 15
Sub-total 20 16.4 20 15.5
Distributaries 6 6.1 7 5.4
Water courses 21 20.2 20 6.5
Sub-total 27 26.3 27 11.9
Total 47 42.7 47 27.4

The Panel of scientists has attempted a confirmation on the basis of rise
of groundwater as a result of infiltration from various sources. Taking the rise
of groundwater per year equal to 1.5 feet and assuming a 25 per cent storage
coefficient, they have estimated water accumulation in 30 million acres equal
to 11.3 MAF (1.5 x .25 x 30= 11.3 MAF). Use of a figure of 1.5 feet rise with
25 per cent storage coefficient and without giving attention to the component
of sub-soil flow, this figure is a poor proof.

It is proposed to pump 49.5 MAF of groundwater. This will constitute 20
MAF of seepage and 29.5 MAF to be drawn from the reservoir. The quantity
of water to be mined is thus:








Ahmad: Waterlogging and Salinity: Comment 375

a) from good quality groundwater zone ... 24.2 MAF
b) from bad quality groundwater zone ... 5.3 MAF

Assuming 15 per cent of this water to be seeping back and assuming 25 per cent
to be the storage coefficient, the depth of groundwater to be lowered to yield
the required discharge will be:
24.2 0.85
Good quality groundwater zone = x 3.58 feet
23 0.25
5.30 0.85
Bad quality groundwater zone = x 2.58 feet
7 0.25
As it is now established that the storage coefficient is about 12 to 14 per cent,
the fall of groundwater per year to give the above yield will be doubled,'i.e.,
about 7.0 feet per year in good quality groundwater zone and about 5.0 feet
in bad quality groundwater zone.
Defects while Pumping this Order of Water
If this programme of pumping is followed, a fall in the groundwater table
of 7 feet per year is expected so that the watertable will be lowered down to
100 feet in 14 years. Let us examine this suggestion for SCARP 1. In this area,
tubewells are installed in which the length of housing is 90 feet and the impeller
of the turbine pumps are located about 70-75 feet below surface, i.e., about
60-65 feet below average watertable, at the time of the implementation of the
scheme. These wells would pump 3 to 3.5 cusecs with an average depression
head of 18 to 20 feet (see, Fig. 1).

If the mining is to be done as planned with a fall of 7 feet per year, the
watertable will be below the impeller after 9 years of the operation. All the
2,000 tubewells of SCARP 1 will become useless if the groundwater is mined
as proposed. The 3.0 cusecs discharge was started to be pumped with 20 feet
of depression and 40 feet of water cushion. After five or six years, the cushion
will be eliminated and water will be pumped by the depression alone. Work-
ing of the tubewells may become doubtful. If the conception of free surface
opening on the discharge face as put forth by Peterson, Isrealson and Hansen
holds [2], then the tubewell of SCARP 1 will stop working when the water-
table goes down to 30-40 feet from its present level, i.e., after 4 to 5 years of
the pumping to mining capacity. The 2,000 tubewells of SCARP installed
to work for 40-50 years shall have to be scrapped much earlier than their
assumed life.

If the watertable is to be taken down to 100 feet by tubewell pumping
then the length of housing pipe needed is 160 to 170 feet with impellers located
at 150 feet and the strainer starting below 170 feet. This design of tubewell
is not being followed even in other SCARP areas.








The Pakistan Development Review


------------
10.0 ORIGINAL I S.S.W.L.
Jl t
30.0
I 20.0
I I
I I
4Fi


PUMP MOTOR


ORIGINAL GROUND SURFACE

1 PUMP HOUSING CASING



GRAVEL SHROUDING

WATER SURFACE WELL WHEN PUMPING






B 8OWL ASSEMBLY


S75

r--eo 6
-80
CONCENTRIC REDUCER



10 SLOTTED TUBEWELL CASING. 180 SLOTS
BY 2 TO 3 TO PROVIDE 30 SQUARE INCHES
OF SLOTTED OPENING PER FOOT OF CASING



S210


SEAL PLATE


220








Ahmad: Waterlogging and Salinity: Comment 377
Loss of Component of Sub-irrigation if Watertable is Lowered
When Ghulam Mohammad wrote his comments, the data on the amount
of sub-irrigation was still preliminary.

Recently detailed studies [3] have been completed on sugarcane and cotton
crops. The former can grow in high watertable and the later needs a deep water-
table. These studies have shown that a considerable amount of the requirements
of a crop is satisfied from the soil moisture if the watertable is high.
Puming Saline Water and its Disposal
The Panel's suggestion to export 3.9 MAF of water with 4000 ppm to lower
regions and to make arrangement ultimately to arrange for the disposal of about
one MAF of water of 10000 ppm by surface evaporation also needs careful
consideration. During three or four summer months from May to August,
water is sufficient in rivers to mix 4 MAF (about 5,500 cusecs) of water and
cause no harm to ultimate increase of salts but during the remaining 8 months,
the river discharges are low and mixing this order of saline water will have
serious problems.

Again, to evaporate about one MAF of water we need an exposed surface
of about 270 square miles as in this region about 5 cusecs are evaporated from
one square mile of the surface. The obvious course appears to be not to touch
the saline water and to take such measures as to obtain the requirements
without the mining of saline groundwater.
A Suggestion for the Solution of the Problem
The Panel has worked out that 58.8 MAF of water is to be made available
at the fields. The present irrigation canal system diverts 48 MAF and makes
available 24.3 MAF at the fields. The rest 34.5 MAF is to be pumped
from the groundwater storage. This is to be made up of 20 MAF from seepage
of canals and 14.5 MAF to be drawn from mining operation.

We know that during the 4 summer months from the beginning of May to
the end of August, we have more river water supplies than we can utilize.
Suppose we do not pump any groundwater during the 4 summer months.
We can arrange our requirements from improved river diversion and further
digging of canals. If we spread the pumping uniformly over the full year, then
during the four summer months, we have to pump 11.2 MAF of water, During
summer we have available water in our rivers. It needs arrangement to divert it
on the land and during this period we can do without pumping. If we can
succeed in this suggestion then we need only 23.3 MAF from groundwater for








The Pakistan Development Review


the next eight months. The source of this much water can be from seepage of the
existing canal (20 MAF) and seepage from the new diversions. We can meet
our requirements from the seepage only.

With a storage coefficient of 10 per cent a one foot rise of water in 30
million acres can store 3.0 MAF. During summer, canals run at full supply, tem-
perature is high, and better saturated sub-soil connection exists, so that sufficient
seepage is possible. High summer rainfall and high stages of rivers can also be a
feeding source. We may take measures to sec that as much water infiltrates
into the formation as possible. Other measures to feed the aquifer can be :
i) dam water in all drains by providing over-shot gates at proper places,
ii) dam water in all non-perennial canals by providing over-shot gates
at proper places and time,
iii) deepen all depressions and make their beds sandy and fill them with
water during summer,
iv) construct new canals and keep them full after flood season by
providing gates,
v) encourage extensive cultivation of rice,
vi) fill all village ponds, depressions, and lakes with water and adopt
measures to keep their bed pervious,
vii) encourage porous shingle beds in places where water can be diverted
to fill the formation.
These measures will feed the aquifer during the four summer months.

As soon as the rivers fall we shall start pumping intensively. We shall not
only pump all the seepage but also mine the groundwater and take it down if
need be to the limit of pumping by centrifugal pumps. The average lowering may
even exceed five feet. With the approach of summer, with more water in the
rivers, the pumping may stop progressively and completely during the monsoon
period to feed the aquifer, so that the mined zone is charged again with water.
It is true that with the watertable at 10 or 15 feet more evaporation or evapo-
transpiration loss occurs but the stoppage of pumping during summer,
feeding from high stage river and heavy monsoon rainfall will all fill the
aquifer emptied during dry months.

This system of management of water resources has many advantages. By
this system we will
i) mine the groundwater equal to our requirements,
ii) use cheap and durable centrifugal pumps with low lift,







Ahmad: Waterlogging and Salinity: Comment 379

iii) use shallow multiple strainers to pump 2 to 4 cusecs from each unit
of pumping set.
iv) not pump saline groundwater as multiple strainers will be installed
to pump the top 70 to 100 feet of the aquifer,
v) replace the stagnant groundwater richly charged with carbonates
and bicarbonates as a result of action of root zone by fresh rain
water, rich in oxygen and most beneficial to crops,
vi) start fluctuating the groundwater which will rise during summer
and will fall by several feet during the remaining eight months, thus
creating a system of natural drainage as exists along the flood plains,
vii) not pump saline groundwater, which would introduce the problem
of aquifer deterioration, nor have a problem of disposal of highly
saline water.
viii) water highly charged with carbonates and bicarbonates will be
replaced by rain infiltration, and the problem of conversion of
normal soil into alkaline impermeable soils by use of bicarbonate
charged water will be remedied.

The financial aspect of these suggestions can further be examined but it is
certain that when we have more summer supplies available, we should utilize
them by ever-lasting canals, requiring little maintenance as against short lived
tubewells with costly maintenance. Integration of the presently constructed
storage at Mangla can be so incorporated as to reduce pumping. When
we need winter supplies we may install cheap, shallow multiple tubewells.
The efforts of the farmers can even be integrated to pump during winter both
for drainage and for extra supplies.

These are the suggestions which can be applied in the Punjab and Bahawal-
pur or where significant pumpable good quality aquifer exists such as along
the strip of the Indus in Sind or in Khairpur West or in Larkana-Shikarpur
Districts. This suggestion is not workable for Ghulam Mohammad Barrage
in general and the lower region of the Sukkur Barrage System adjoining the
Ghulam Mohammad Barrage region having high watertable of a very highly
saline nature. Here, we have to create good quality aquifer before tubewells
can be installed. Tile and open drains are the solution and there is no
doubt about the success of this type of drainage in that area.

In the end, it is admitted that Pakistan is much obliged to the American
scientists which constituted the Panel for their great service to this country.








380 The Pakistan Development Review

They not only thoroughly studied the complicated problem in such a limited
period but have suggested a solution. Their study of the problem will remain
a source of guidance for generations to those who are to deal with the land
and water problems of this country. To the scientists it has given new
avenues to explore. Science progresses on new and novel ideas.


REFERENCES

1. Ahmad, Nazir, A Discussion on Hydrological Estimation of Water Resources
as Put Forth in Chapter VI of Kennedy Mission Report. Special Report
No. 255-Ph/ Seep.-53/63. (Lahore: Irrigation Research Institute, 1963).
2. Ahmad, Nazir and Mohammad Akram, Evapo-transpiration as A Function of
Depth to Watertable and Soils. Special Report No. 291-Ph/Soil. Ph.-7/65
(Lahore: Irrigation Research Institute, 1965).

3. Dean, F. Peterson, O. W. Israelson and V. E. Hansen. Hydraulics of Wells.
Bulletin 35. (Logan: Utah State University, March 1952).

4. Ghulam Mohammad, "Waterlogging and Salinity in the Indus Plain: A Criti-
cal Analysis of Some of the Major Conclusions of the Revelle Report",
Pakistan Development Review, Vol. IV, No. 3, Autumn 1964.
5. United States Department of Agriculture, Soil Conservation Service, Irriga-
tion Pumping Plants. Chapter 8. (Washington, D.C.: United States Depart-
ment of Agriculture).












Waterlogging and Salinity in the Indus
Plain: Comment

by
FRANK M. EATON*

Not only does Ghulam Mohammad's contribution on waterlogging and
salinity in the Indus Plain [5] reflect a wide understanding of the agricultural
problems of Pakistan but the clarity of his presentation is commendable. My
comments all have to do with water quality and drainage problems in this vast
irrigated area with the future rather than the immediately present problems
primarily in mind. I trust that all statements will be regarded as constructive
rather than critical.
The changes now occurring with irrigation in the compositions of the
initially high-quality canal waters of the Indus Plain as these waters become
groundwaters, appear to be little different from the past changes which occurred
more slowly but which are responsible for the diverse compositions of the
present groundwaters. Many of these present-day groundwaters were left be-
hind by the flood waters which deposited the valley alluvium. The flood waters
left on the land surface underwent concentration by evapotranspiration with
precipitations of CaCO3 and losses of Mg in the form of compounds of salica.
As a result of these precipitations there were increases in the proportions of Na.
That little of the salt being left in the soils and groundwaters of Pakistan
with irrigation is now being carried to the sea is indicated by the finding that
a sample of the Indus River collected near Karachi in February 1953, when
the discharge was very low, was only a little more saline than that of waters
sampled near the upper head works [3]. The Karachi sample was reported to
have been about 80 per cent return flow from surface runoff and drainage
from irrigated lands.
The fact that little of the salt brought onto the lands of the Indus Plain
by the rivers and canals is being discharged into the sea, represents a major
long-time threat to the permanency of the agriculture of West Pakistan unless
a suitable means of disposing of the salt residues of these irrigation waters

*Dr. Frank M. Eaton is the Associate at the Agricultural Experiment Station, University
of California, Riverside, California.







382 The Pakistan Development Review
is developed. History has repeatedly demonstrated that a permanent agriculture
requires that the salts added to irrigated lands be balanced by a commensurate
salt removal. The mere fact, however, that a "salt balance" is achieved may be
meaningless if the balance exists only after the lands are too saline for a self-
supporting agriculture. Drainage facilities should be established before, rather
than after, an agriculture is impoverished.

One automatically cringes at the thought of discharging saline drainages
into the canals and rivers that are supporting downstream agriculture. The
destruction of old agriculture to promote new ones can provide no mental
comfort. The longevity of an agriculture which supports many millions of
people should be viewed in terms of centuries rather than on the basis of an
expedient which may suffice for only a limited number of years.

The Report on Land and Water Development in the Indus Plain [81
and the Panel's paper estimate that with recycling of the groundwater to supply
additional irrigation water and at the same time prevent a further increase in
waterlogging, the groundwaters will, with 10 to 50 years of pumping, have
become too saline for further use.
The reports further recognize that the quality of the groundwaters under-
lying the Indus Plain are uneven: "... pools of poo quality water are inter-
spersed among the good." By the data presented for the Northern Plain, only
one-third of the groundwater contains less than 500 ppm of total salt. A total
of 38 per cent contains more than 1000 ppm of salt. The reports recognize that
a disastrous infiltration of bad waters into the good will occur if the elevations
of the good waters are reduced by pumping below the elevations of the bad.
In other words, the idea is accepted that both the bad and good waters must be
simultaneously pumped but the statement on how the bad waters should be
disposed of is not very specific. It is suggested only that the bad waters might
be discharged into lagoons or returned to the rivers during flood periods.

Two questions are raised by these proposals, particularly since the areas
of bad waters will progressively expand during the 10 to 50 year periods of
pumping until all waters are salinized. When the good waters are exhausted,
Pakistan will again be dependent on canal waters. Neither the present nor
future bad waters which require pumping will necessarily be adjacent to the
rivers. The canals for distributing irrigation waters were designed for distribu-
tion only and it would appear to require much planning and construction of
newdrainage works to carry away the discharges of widely scattered wells pumped
only to protect the quality of the pools having good water. The problem of
disposing of the saline groundwaters is recognized as one which will become








Eaton: Waterlogging and Salinity: Comment 383

progressively more acute as pumping is continued. Eventually, there will be
only limited sources of good groundwaters which can be pumped and the dis-
appearance of good waters will become more rapid if the bad waters are not
pumped.

It seems important that decisions should be made now, rather than later,
as to: i) who will pay for pumping the bad waters and, ii) how will they be
disposed of?

Without pumping, the levels of all groundwaters will continue to rise into
root zones in the future as they have risen in the past. Waterlogging of once
fertile lands has been progressive in the past in Pakistan. Without a drainage
system which is designed with the same care that the distributary system was
designed, the problem of land abandonment will become more acute. As lands
are abandoned because of waterlogging and salinity, it is reasonable to believe
that farmers will be no more able to pay for drainage systems in the future
than they are at present or have been in the past.

The two reports which have been cited emphasize advantages of the vertical
(pumping) drainage systems over horizontal systems. They point further to the
difficult and high costs of integrating a drainage system with the distributary
system. It may be true that it would be less costly to dispose of the saline drain-
ages by pumps discharging into special canals than by a horizontal system but,
if so, only with the provision that the government, or some other agency, would
provide and operate the pumps and dig the canals that would dispose of the
bad waters. When pumps no longer yield good waters, the agriculture of Pak-
istan will be in the same position that it was in before the present pumping
episode was started.
Water Quality
The water quality statistics, employed by the Panel in its initial report
and in response to the articles by Ghulam Mohammad, rely on salt con-
centrations expressed as parts per million of total salt. There is no
summary of the percentages of high-sodium, high-bicarbonate groundwaters,
or of the concentrations of calcium and magnesium relative to the concentra-
tions of carbonates and bicarbonates. With values for these components in the
groundwaters, it is possible to estimate the alkalinity hazards and the effects
of the waters on soil permeability. From water analyses based on the concentra-
tions of individual ions, it is possible to estimate the percentage of the applied
water which must be passed through and out of the bottom of the root zone
to carry salts away fast enough to permit yields 80 per cent as high as those
possible on non-saline lands. Also, with these values it is possible to estimate








384 The Pakistan Development Review

the amount of gypsum which should be applied to the water or to the land
to prevent high alkalinity, serious soil impermeability, and the deficiencies of
the calcium and magnesium required for normal growth. Knowledge of the
existence of the alkali problem, both present and future, is indicated by the
inclusion, in the paper by Dorfman, Revelle, and Thomas, of a discussion of
the "sodium hazards". There were no statistics to indicate the magnitude of
the problem represented by the composition of the groundwaters or of the
proportion of the land which is now so high in sodium that leaching is too slow
to be fully effective. No mention is made of the use of gypsum as a corrective.

On the basis of the old groundwater analyses, which the writer was able
to find in Pakistan at the time of his three-month visit in 1952-1953, the problem
of excess sodium and high alkalinity in soils and groundwaters impressed him
as being serious and deserving of careful attention. Since that visit, Hausenbuiller,
et al [6, pp. 356-364] were similarly impressed and recommended applications
of gypsum where needed. The writer recalls experimental data from the vicinity
of Montgomery which demonstrated outstanding yield benefits from the use
of gypsum. No practical substitute for the use of gypsum on high sodium alkali
lands is known.
Ghulam Mohammad has reviewed [5, pp. 357-403], the now-available ana-
lyses of groundwaters of the Indus Plain. Even on the questionable assump-
tion that 1.25 me./l of residual sodium carbonate may be safe (see, later dis-
cussion), the data show that the less saline waters are commonly so high in
sodium and/or bicarbonate as to make their use hazardous unless they are
mixed with canal water or treated with gypsum.

Private interests will undoubtedly avail themselves of the groundwaters of
Pakistan by pumping only so long as the qualities of these waters permit profit-
able crops. When there is no longer a profit, the wells will be abandoned, after
which the watertables will again rise. It seems doubtful at this stage that private
funds will be available for the construction of the drainage system which should
have been established when the distributary canals were constructed. The cost
of a country-wide drainage system is so great that it seems doubtful that public
agencies can now undertake it.
On-Farm Drainage
It was for the foregoing reason, and the foregoing reason only, that the
writer in his FAO report [3] suggested a type of drainage system which he
believed the farmers themselves could install and maintain. Such a system, al-
though not ideal, may be the only recourse possible, now or in future, in many
areas of Pakistan.








Eaton: Waterlogging and Salinity: Comment 385
Under ideal practice, saline drainages should discharge into the sea or
into natural closed lakes or large land depressions. Horizontal drainage systems
of large scale are expensive and, as noted in the reports cited, they seriously
interfere with water-distributary systems.

The lands of Pakistan tend to be flat and for that reason, the drainage
canals would have to be of large capacity and often augmented by pumping to
obtain the necessary discharges. Also to accommodate the necessary depths of
field drains, the public canals would have to be deep.

As has been repeatedly noted by others, Pakistan has a great surplus of
arable land in relation to its water supply. It is now apparent that the distri-
butary system was designed to serve more land than could be cropped at any
one time. It seems possible, if not probable, that the planners hoped thereby
to at least slow down the rate of rise of the watertables, and thereby to post-
pone waterlogging. Over vast areas waterlogging has now become acute.

With the great excess of arable land, the writer believes that the cultivated
acreages could appropriately be cut back to approach the land that can be
served by canal or good-quality groundwaters. With such cut backs, there will
be continuously idle lands that can be converted to evaporation flats-areas
which are surrounded by low dikes or areas upon which the saline drainages
can be spread by networks of furrows.

In the light of the effects of canal seepage and rainfall on rising water-
tables, in addition to the necessary leaching to remove existing salinity and to
continuously remove the salts deposited in soils with irrigation, it is possible
to estimate the required areas of the on-farm evaporation flats in relation to
the area of the land irrigated. With knowledge of evaporation rates, leaching
requirements, rainfall, and surface runoffs, such estimates become quite simple.

Under the evaporation-flat system, the farmer himself would install the
field, drains (tiles or ditches) and the disposal ditches leading to his evaporation
flat. Since the field and connecting drains should be installed to depths of
upward to seven feet or more, small on-farm deep collecting sumps are necessary
for the accumulation of the day-to-day drainage. Pumps, whether power
or Persian wheel, are necessary for the discharge of drainage effluents from
the sumps onto the evaporation flats.

The installation of on-farm evaporation flats is, of course, not an ideal
substitute for country-wide drainage systems. But the method, as an alter-
native, is regarded by the writer as one of much promise under the existing








386 The Pakistan Development Review

circumstances and one which would permanently reverse the downward trend
in production which has resulted from waterlogging and salinity.

Deep field and collecting drains should always serve the double purpose
of disposing of saline wastes and of providing deep, well-aerated root zones.
Water Quality Evaluation
Tf a water is to be used for irrigation, it is deserving of a careful chemical
analysis to make possible estimates of how it can be used most effectively.
From analyses for each ion expressed in milligram equivalents per liter (me./l),
it is a simple matter to calculate leaching, or drainage, requirements and to
estimate, also, the amount of gypsum which should be applied to maintain
permeability and high production.
Ghulam Mohammad has pointed to a weakness in the Revelle Report in that
emphasis was placed on total salinity with a neglect of the significance of bi-
carbonate in the precipitation of calcium and the resulting higher sodium per-
centages. He regards it as probable that many groundwaters which the Panel
recommended as suitable for irrigation would result in low soil permeability
and high alkalinity unless mixed with large quantities of canal water or used
with heavy applications of gypsum. Because of insufficient canal water, the
necessity of gypsum, and the costs of development, he recommends the elimina-
tion of tubewell installations over the Punjab and Bahawalpur, and undoubtedly
elsewhere, except where sodium and bicarbonate concentrations are found to
be low relative to calcium and magnesium. On the other hand, many waters
that are now unsuitable for irrigation because of high bicarbonate can be
successfully used by additions of gypsum. Reference will be made in a subse-
quent paragraph to the nature of the experimental evidence which led the Panel
to regard 1.25 me./l of residual sodium carbonate in irrigation waters as
"probably safe". Workable gypsum deposits are available in Pakistan and
experimental evidence exists in Pakistan which shows that notable benefits of
gypsum applications have resulted even in some of the canal-irrigated land.
Hausenbuiller, et al [6, pp. 357-364] note that while power and machinery for
mixing gypsum with water may be expensive, applications of the finely powdered
material directly to the land is practical.

Ghulam Mohammad refers to statements by Hanson, Bower and Williams on
advantages of maintaining subsurface waters within the lower root zone if care
is taken to insure that adequate salinity control is exercised. Although it is
true that water may be effectively stored in the deeper root zone, as in the
polders of Holland where salinity is not usually a problem, the dangers of
extending the concept to some of the irrigated lands of Pakistan are obvious.







Eaton: Waterlogging and Salinityi Comment 387

If an irrigation water containing 10 units of chloride is used over a few years
to produce a uniform 10 per cent of leaching, the leachate will contain 100 units
of chloride; with 20 per cent of leaching, the leachate will contain 50 units of
chloride; but with only 1 per cent of leaching there eventually will be 1000 units
of chloride in the drainage. Drainage systems serve the double purpose of
increasing the depth of aerated soil and of removing salt from the land. Plants
take up more salt-relative to water uptake-as concentrations are increased
and it is the salt in the plant that depresses growth.
Prior to my short visit to Pakistan in late 1952 and early 1953, I had spent
a good bit of time developing a set of simple equations for evaluating the
quality of irrigation waters in the light of field and experimental responses.
Those equations were included in my FAO report to Pakistan [3] and later
published with the background information as Texas Agricultural Experiment
Station Miscellaneous Bulletin 111, 1954. Since then a few minor simplifications
and changes in constants have appeared to be advantageous.
Inasmuch. as CaSO4 added to a soil or water increases the SO4 content,
one first computes the Ca requirement of the water and then adds I the required
Ca to the sum of C1+IS04. For a number of plants, S04 has proven to be
only half as toxic as Cl, equivalent for equivalent.
Calcium and Gypsum Requirements
The object here is to produce leachates with no more than 70 per cent Na.
Required Ca: me./1 = sum of a, b, and c as shown below:
a) Ca+Mg needed, if any, so that the Na per cent will not exceed 70:
Na x 0.43 (Ca + Mg) Retain + or sign
b) Compensate for CaM+g that will probably be precipitated:
(C03+HCO3) x 0.7
c) Compensate for the Ca + Mg in excess of Na that is removed from
the land by average crops: Add 0.5 me./l. This value is suggested for
Pakistan because of the large amounts of forage which is carried into
the villages. Without such removals the value 0.3 me./l is suitable.
Gypsum Equivalent of required Ca:
sum of a, b, and c X 234 =pounds of gypsum, if any, per acre foot of
water. (See, guide in Table I).
Leaching Requirements
RL = Leaching requirement
Sw = Salinity of the water expressed as Cl + SO4 + I required Ca.
Mss = Mean soil solution concentration expressed as: Cl + ISO4 i.e., the
average of the water and leachate.








388 The Pakistan Development Review

TABLE

GUIDE FOR COMPUTING THE LEACHING AND

Calculations (see
Calcium
Composition of water me./liter
(a) (b)
Nax0.43 CO3+HCO3
Water EC x ------- Minus x 0.7
No.** (10)6 Ca Mg Na C03 HC03 S04 C (Ca+Mg)


1 52 0.21 0.12 0.19 0.00 0.34 0.05 0.16 -0.25 0.24

2 350 1.15 0.93 1.78 0.00 1.14 0.67 1.72 -1.315 0.798

3 420 2.35 0.75 1.39 0.00 2.94 0.98 0.56 -2.503 2.058

4 985 4.17 2.26 3.81 0.00 2.76 5.51 2.11 -4.80 1.93

5 789 0.24 0.02 7.28 0.00 2.39 2.48 2.47 2.87 1.67

6 2170 2.33 0.57 17.43 0.00 1.92 6.30 11.92 4.59 1.34

**Water sources: (1) San Joaquin River, California, (2) Gage Canal, Riverside, California, (3)
California, (6) Well, Coachella Valley, California
*A mean soil solution (Mss) value of 30 is used for this calculation.
tThis is the per cent of irrigation water applied which must be passed beyond the root zone to









Eaton: Waterlogging and Salinity: Comment

I

GYPSUM REQUIREMENTS OF IRRIGATION WATERS

formulas under text (pages 387-391)


Requirement


(C) (d)
Crop Ca Require-
removal ment in me./I.
adjustment [(a)+(b)+(c)]


Leaching requirement


Sw= LR=
Cl + SO4 2xMss*-Sw Swx100
+ I required
calcium 2xMssSw
(per cent)


Appraisal
Gypsum
requirement Leaching
(d)x 234= require-
lbs. Gyp./ac. ment
ft. water in
per centt


----------_~ --- -- ---- F-- ^-

0.30 0.29 0.33 59.67 0.5 68.0 0.5

0.30 -0.21 2.10 57.90 3.6 None 3.6
(None)
0.30 -0.14 1.05 58.95 1.8 None 1.8
(None)
0.30 -2.57 4.86 55.14 8.8 None 8.8
(None)
0.30 4.84 6.13 53.87 11.4 1130.0 11.4

0.30 6.23 18.18 41.82 43.5 1460.0 43.5

Tracy Mendota Canal, California, (4) Colorado River, U.S.G.S. 1950, (5) Wel, Bakersfield,


keep salt from accumulating beyond levels consistent with good crop performance.


_I








The Pakistan Development Review


Sw x 100
RL =
2 x Mss- Sw
For annual plants of low salt tolerance ... Mss = 20
For annual plants of medium salt tolerance ... Mss =30
For annual plants of high salt tolerance Mss =75
For standard water-quality comparisons, the use of Mss = 30 is suggested.
Comments on the Derivation of the Equations
The leaching requirement, RL, represents the percentage of the applied
irrigation water which should be passed through and out of the root zone as
leachate for the maintenance of yields averaging 80 per cent as high as on
similar non-saline soil. If the equations, when converted to acre inches of
leachate, for example, show that there should be five acre inches of leachate,
this amount remains valid irrespective of whether the actual leaching is brought
about by irrigation or by rainfall, i.e., the rainfall may produce the leaching but
the acre inches of required leachate computed on the basis of the amount
of irrigation water applied is not changed.

In the RL calculation, unreasonably high values result if either the electrical
conductivity or sum-of-cations is substituted for Cl + iS04, because HCO3
would be included; HC03 is not significantly accumulated by plants. But its
presence as NaHCO3 depresses Ca and Mg accumulations. These ions, in
ample amounts, are essential for good crop production. It is more economical
to avoid the adverse effects of HCO3 by the use of gypsum than by extra leach-
ing. In the instance of the Indus River at Sukkar on January 30, 1953 [3].
the leaching requirement by the present equations is 1.4 per cent. But on
the basis of electrical conductance or sum of anions or cations, the require-
ment is found to be several times greater and unreasonably high.

The expression, in the Ca requirement equations, Na x 0.43 shows the
amount of Ca + Mg needed for 70 per cent Na. If a water contains 5 me./l
of Na then Na x 0.43 shows that 2.15 me./1 of Ca + Mg will be needed to
give 70 per cent Na. The deficiency or excess from 2.15 is carried forward with
the plus or minus sign in computing the Ca requirement: a+b+c.

The present Mss values (used in the denominator of the RL equation),
are lower than those previously suggested because of experimental results [4,
pp. 411-416] showing that chloride accumulates at root surfaces and gives rise
to higher accumulations in plants on a soil than on a water culture even though
the substrate concentrations are maintained at the same level.








Eaton: Waterlogging and Salinity: Comment 391
The extent of precipitation of CaC03 in soils is a function of the CO2
partial pressure in the soil atmosphere and the concentrations of the reacting
constituents. The latter are largely determined by leaching rates but estimates
of CO2 partial pressures in soils are difficult since they are dependent on the
density in the soil of living and dead roots, their respiratory rates, and the
freedom of gaseous exchange between the soil and the air above. The pH of
soils measured in the laboratory after exposure to the atmosphere are usually
much higher than when measured in place in the field.

Only a few good data are available on the proportion of the HCO3 in
water supplies that are normally precipitated in soils. Among the best of these
are the results presented by Pratt, et al. [7, pp. 185-192]. It was found that
in the order of 50 per cent of all the HCO3 applied by an irrigation water with
"88 per cent sodium possible" (i.e., Ca- 2.43, Mg--0.76, Na -1.46, and
HCO3 3.00 me.!l) was precipitated both in a 20-year lysimeter experiment
and in an orchard irrigated for 38 years. In the foregoing "Ca requirement"
equations use is made of Pratt's average value for loss of HCO3, i.e., 50 per
cent, but in addition a 20 per cent allowance is made for the precipitation of
Mg largely in the form of silica compounds, i.e., the value 0.7 x HCO3 is used
in computing Ca + Mg requirements.

It is unfortunate that each of three extended (21 months to 4 years) and
carefully conducted experiments on the significance of CO 3 HCO3 in irrigation
waters failed to take account of the importance of CO2 partial pressures in the
soil atmosphere on the extent of precipitation of CaC03 (Wilcox, et al[9, pp.
259-266]); Babcock, et al [2, pp.155-164]; and Hausenbuiller, et al[6, pp.
357-364]. In each of these experiments the plants-respectively, Rhodes
Grass, alfalfa, and Bermuda Grass-were grown in containers and irrigated with
waters having various ratios of Ca: Na and HC03: Cl. The oversight in the
experimental designs is represented by the fact that the containers were not
surrounded by densities of plants equal to those of the test plants in the con-
tainers. With the foregoing provision, lateral light would have been reduced
and the top growths would have been more nearly proportional to soil area.
But with the tops spreading out, the root densities must have been very high
in the limited soil volumes (2, 32, and 5 gallons, respectively). The production
of respiratory CO2 being somewhat proportional to root density, the precipita-
tion of CaCO3 would, to a corresponding extent, have been inhibited by the
high CO2 partial pressure, and the development of high ESP would have also
been restricted. Babcock, et al. [2]make the observation that while little CaCO3
precipitation occurred in their soils, it did occur in their collecting pans as the
leachates came into equilibrium with the outside air.







392 The Pakistan Development Review

Hausenbuiller, et al [6] obtained a correlation coefficient of .984 between
the residual Na2CO3 in 11 waters and the exchange sodium percentages found
in the top eight inches of 11 soils and yet five of the waters contained less HCO3
than Ca + Mg. In accord with Pratt, et al. [7] much CaCO3 may be precipitated
even though there is no residual Na2CO3 in the water. Pratt, et al. [7] found
rather large increases in the ESP and pH values of the irrigated soils in both
the lysimeter and field experiments.

REFERENCES
1. Asghar, A.G. and M.A. Hafeez Khan, "Behaviour of Saline-Alkaline Punjab
Soil Under Reclamation", Proceedings of Punjab Engineering Congress.
(Lahorei Punjab Engineering Congress, 1955).
2. Babcock, K.L. et al., "A Study of the Effects of Irrigation Water Composi-
tion on Soil Properties", Hilgardia, 29(3), 1959, pp. 155-164.
3. Eaton, F.M. FAO Report No. 167 to the Government of Pakistan on Certain
Aspects of Salinity in Irrigated Soils. (Rome: FAO, September 1953).
4. ----------, and J.E. Bernarelin, "Mass Flow and Salt Accumulation
by Plants on Water Verus Soil Culture", Soil Science, Vol. 97, No. 6, June
1963.
5. Ghulam Mohammad, "Waterlogging and Salinity in the Indus Plain: A
Critical Analysis of Some of the Major Conclusions of the Revelle Report",
Pakistan Development Review, Vol. IV, No. 3, Autumn 1964.
6. Hausenbiller, R.L., M.A. Haque and Abdul Wahab, "Some Effects of Irriga-
tion Waters of Differing Quality on Soil Properties", Soil Science, Vol. 90,
1960.
7. Pratt, P.F., R.L. Branson and H.D. Chapman, "Effect of Crop, Fertilizer
and Leaching on Carbonate Precipitation and Sodium Accumulation in Soil",
VII International Soil Science Soc. Cong. Trans. 2, Vol. 11, 1960.
8. White House, Department of Interior Panel on Waterlogging and Salinity in
West Pakistan, Report on Land and Water Development in the Indus Plain.
(Washington D.C.: Suptt. Doc. January 1964).

9. Wilcox, L.V., G.Y. Blair and C.A. Bower, "Effect of bicarbonate on suit-
ability of water for irrigation", Soil Science, Vol. 77, 1954.












Waterlogging and Salinity in the

Indus Plain: Rejoinder
by
GHULAM MOHAMMAD*
Most of the points raised by the Panel members, Drs. Roger Revelle,
Harold Thomas and Robert Dorfman, have been answered in the comment by
Dr. Frank M. Eaton. Dr. Nazir Ahmad has further elaborated some of the
issues involved. The author will confine his remarks to two basic issues, namely,
pumping of water for irrigation purposes in the non-saline high quality ground-
water areas in the Northern Zone of the Indus Plain and provision of horizontal
sub-surface drainage facilities in areas where the groundwaters are saline and
unfit for irrigation use.
The author is happy to note that the Panel members acknowledge the
significant contribution made by private tubewells to the productivity of agri-
culture in West Pakistan. The author agrees with the Panel members that private
tubewells will be developed mainly in areas that have adequate supplies of high
quality groundwater and not in areas where the groundwater is too saline to be
applied to land without dilution with canal water.
Ina previous article, the author proposed that horizontal sub-surface drain-
age facilities should be provided in the saline groundwater areas [5, pp. 387-395].
The Panel members do not agree with this and propose instead deep tubewells
for irrigation as well as for drainage purposes. They suggest that with the use
of deep tubewells and canal water the salt be flushed out of the root zone and
washed downward with recycled pumped water to be stored underground.
The Panel members consider that drainage structures are expensive, and
argue that provision of drainage facilities should be postponed as long as
possible (p. 350). The author considers thatthis is a dangerousrecommendation.
As pointed out by Dr. Eaton (p. 382), the areas of bad waters will progress-
ively expand during the next 10 to 50 years until all waters are salinized. With
increasing salinity of groundwaters, agricultural production will progressively
decline unless large scale drainage channels are constructed to remove part of
the pumped waters out ot the area.
*The author is a Senior Research Economist at the Pakistan Institute of Development
Economics. He is indebted to Dr. Bruce Glassburner, Senior Research Advisor, Mr. Keith
Griffin, Research Adviser in the Institute and Mr. Carl Gotsch of the Harvard Advisory Group
at Lahore for their valuable comments on the earlier draft. The author is grateful to Mr.
Mohammad Ghaffar, Research Assistant, for assistance in computations. Responsibility for
the views expressed and for any errors is entirely that of the author however.








394 The Pakistan Development Review
Dr. Eaton has raised two important questions on this issue (p. 383). He asks
i) who will pay for pumping the bad waters and ii) how will these be disposed
of?
As stated by Dr. Eaton, neither the government nor the farmers will be able
to pay for the drainage structures when all the groundwaters have been salin-
ized; certainly, they are better able to do so now when only part of the ground-
waters are salinized.

It would be in the interest of Pakistan to install tubewells in the non-saline
best quality groundwater areas only. These areas lie in the upper reaches of
the Rechna, Chaj and Bari Doabs and along both sides of the rivers in the
Punjab and Bahawalpur. Farmers are already installing tubewells in these
areas. To keep the groundwater of these areas in good condition, Dr. Nazir
Ahmad has suggested that the canal water supply to these areas should be
increased during the summer season when there is excess water in the rivers.
This would increase the infiltration of fresh water to the groundwater and in
this way these areas could be kept fit for pumping for an almost indefinite period.
According to Harza Engineering Company International, the present river
diversions into the West Pakistan canals are about 83 MAF per year, 48 MAF
in the Northern Zone and 35 MAF in the Southern Zone [9, p. 39]. About 20
MAF of water is lost through seepage and evaporation in the rivers and about
61 MAF goes to the sea mainly during the summer season [9, p. 39]. It should
be possible to divert some 10 MAF additional water to the non-saline ground-
water areas out of the 61 MAF now going to the sea.

If the capacity of canals is increased and additional water is diverted onto
these areas during the kharif season, the rabi water supply can be withdrawn
from these areas. The farmers can install tubewells and meet the full need of
the rabi crops by pumping groundwater. The rabi water removed from these
areas can be diverted to saline groundwater areas in the lower reaches of the
doabs where tubewells cannot be installed on account of high salinity.

In order to encourage the farmers to install tubewells in the non-saline
groundwater areas, electricity should be provided to the whole of this area,
and credit should be extended to the farmers for the purchase of tubewell
materials.
In the remaining areas of the Punjab and Bahawalpur where groundwaters
are relatively more saline, drainage facilities must be provided to remove the
salt from the area. However, a basic problem of these areas is the deficiency of
irrigation water. The capacity of the canals will have to be increased and addi-







Ghulam Mohammad: Waterlogging and Salinity: Rejoinder 395
tional river water will have to be diverted on to these lands to meet the consump-
tive use requirements of crops and to leach down the salts. At the same time
drainage channels will have to be constructed. As pointed out by Dr. Eaton, the
drainage facilities must be provided before, rather than after, the agriculture is
impoverished.

Saline Groundwater Areas
The most damaging recommendation in the Revelle Report was the proposal
to pump water in the saline groundwater areas (having an average salinity of
6000 ppm), to mix it with canal water and to use the mixed water with an
average salinity of 2000 ppm for irrigation purposes [18, p. 281]. The Panel
members now consider (p. 344) that at least in half of the saline area the ground-
water has a salinity of less than 5000 ppm, and this can be used for irrigation
if it is sufficiently diluted with canal water. For justifying the use of this saline
groundwater, the Panel members have developed a set of equations which are
given on pages 348-350 of their paper.

Taking two examples, one with irrigation by canal water and the other
with irrigation by mixed canal and tubewell water, the Panel members have
shown (p. 350) that the salinity of the mixed water can be0.188/0.0192 =9.8 times
larger than that of the canal water. Thus if the surface water has a salinity of
200 ppm, the concentration of the mixed water can be 2000 ppm, corres-
ponding to a groundwater with a salinity of 3800 ppm, mixed with an equal
quantity of canal water.

It appears that the Panel members obtained their result by making two
incorrect assumptions: 1) The depth of irrigation water was taken as .65 feet
(or 7.8 inches) and the interval of canal irrigation was taken as 4 weeks; 2) with
25 per cent increase in water supply with the installation oftubewells, the interval
of irrigation of mixed water was reduced from 4 weeks to 1.5 weeks. The actual
depth of irrigation in West Pakistan is 3 to 4 inches which is about one half
of that assumed by the Panel members. The water is generally applied after 2
weeks. When irrigation supply is increased by 25 per cent, the interval of irriga-
tion can be reduced from 2 weeks to 1.5 weeks, but not from 4 weeks to 1.5
weeks. If the example on page 349 is recalculated by taking depth of irrigation
as 0.325 feet and interval of irrigation as 2 weeks, the salinity concentration
of the mixed water would be 0.188/0.048 or 3.9 times that of canal water. If
the salinity of canal water is 200 ppm, the salinity of mixed water can be 780
ppm, corresponding to a groundwater salinity of 1360 ppm when mixed with an
equal quantity of canal water.







396 The Pakistan Development Review

To use mixed canal and tubewell water having a salinity of 780 ppm for
crops of medium salt tolerance, about 18 per cent additional water will have
to be provided for leaching purposes [18, p. 117]. This would mean that30 per
cent of the tubewell water will have to be pumped for leaching purposes only.
If on the other hand saline water containing as much as 3800 ppm is pumped
and mixed with an equal quantity of canal water and mixed water having a
salinity of 2000 ppm is used for irrigation as suggested by the Panel members,
nearly 67 per cent of the mixed water would be required for leaching purposes
with crops of medium salt tolerance [18, p. 117]. This means that about 80 per
cent of the pumped water will have to be used for leaching purposes only2. In
the case of crops of high salt tolerance such as cotton and barley, the leaching
requirement will be about 25 per cent of the mixed water or about 40 per cent
of the pumped water. Even with the provision of drainage and removal of 40
to 80 per cent of the pumped water as drainage water, there would be deter-
ioration of land due to sodium damage and large quantities of gypsum will have
to be provided to keep the soils in good condition.
Dr. Eaton has developed a method for estimating the amount of gypsum
and the additional amount of water which should be applied to the land to
prevent high alkalinity, serious soil impermeability and deficiencies of calcium
and magnesium required for normal plant growth (see, pp. 387-391).
For saline groundwaters of the Northern Zone of the Indus Plain the
author has calculated, from water analyses of Water and Soils Investigation
Division of West Pakistan WAPDA [7; 15], the gypsum and leaching require-
ments for all groundwaters having a salinity between 3000 and 3900 ppm
in the Chaj and Rechna Doabs according to Dr. Eaton's method. Calculations
have been made for the undiluted groundwaters as well as for the ground-
waters when mixed with an equal quantity of canal water. The results are sum-
marized in Table I. For all groundwaters having an average salinity of 3500
to 3600 ppm, when mixed with an equal quantity of canal water the gypsum
requirements (for the mixed waters having a salinity of 1800 to 1900 ppm)
average about 3000 pounds per acre foot of mixed water in the Chaj Doab
and about 2000 pounds per acre foot of mixed water in the Rechna Doab. The
leaching requirement for crops of medium salt tolerance average about 75 per
cent in the two doabs. This means that about 85 per cent of the pumped water
will have to be used for leaching purposes only.
1 Suppose 100 parts of canal water are used to mature one acre of crop. If 100 parts of
tubewell water are mixed with the same, the total quantity becomes 200 but 36 parts of
additional water is required for leaching purposes to mature 2 acres of crops. Thus canal
water is increased to 118 parts and tubewell water to 118 parts. The 118 parts of canal water
when used alone can mature 1.18 acres of crops. Therefore 118 parts of tubewell water mature
0.82 acres of crop and are thus equal to 82 parts of canal water. The remaining 36 parts of tube-
well water or 30 per cent is used for leaching purposes.
2 Calculated as explained in footnote 1 above.










Ghulam Mohammad: Waterlogging and Salinity: Rejoinder

TABLE I


GYPSUM AND LEACHING REQUIREMENTS OF GROUNDWATERS OF THE CHAJ
AND RECHNA DOABS, UNDILUTED AND MIXED WITH CANAL WATER
FOR CROPS OF MEDIUM SALT TOLERANCE

Groundwater mixed
with canal water in
Undiluted groundwater equal proportion

Doab Salinity of Gypsum Leaching Gypsum Leaching
Well water ground requirements require- requirements require-
numbera per acre ments per acre ments
foot of foot of
water water
(1) (2) (3) (4) (5) (6) (7)


(ppm)
3,000
3,530
3,500
3,580
3,580
3,790
3,790
3,910
3,690
3,030
3,000
3,700
3,650
3,000
3,400


(pounds) (per cent)


4,951
10,144
3,398
4,797
5,316
8,702
5,373
6,512
4,848
5,162
8,955
10,245
4,708
4,572
7,888


343
410
838
384

458
479
2,717
493
447
182
282
305
291


(pounds) (per cent)
2,370 67
4,975 70
1,596 84
2,291 68
2,551 127
4,280 73
2,581 73
3,617 107
2,434 75
2,476 73
4,373 50
5,015 63
2,246 121
2,179 63
3,838 62


Average 3,477 3,070 77
RTLF.17 3,780 3,496 2,226 1,645 95
RTLG.15 3,450 4,844 419 2,312 70
RTLZ.28 3,260 7,495 167 3,648 48
RTLZ.30 3,630 3,393 328 1,589 65
RTLZ.31 3,800 4,530 459 2,167 72
RTLZ.32 3,680 3,868 1,074 1,828 88
RTLZ.33 3,370 nil 321 nil 64
RTLZ.47 3,560 nil 199 nil 52
RTW.28 3,910 1,884 1,132 835 82
RTW.54 3,970 3,945 4,445 1,748 101
RTW.53 3,940 669 321 229 64
R.11 3,990 6,575 700 3,189 81
R.14 3,750 6,573 259 3,178 59
R.15 3,600 5,304 550 2,548 76
RCC.30 3,580 9,287 347 4,535 66


Average 3,685

Notes: a) Well numbers as given by the Water and
Soils Investigation Division of WAPDA
in their publications [7; 15].
b) Assuming Jhelum and Chenab river water
at Trimmu containing 208 ppm [16, p. B-6]


1,963 72

Sources: Columns (2) and (3):
Chaj Doab [7, Tables 2
and 3]
Rechna Doab [15, Tables
2 & 3].
Columns (4) to (7): Calculated
according to Dr. Eaton's
method (see, Table I on
pp. 388-389).


Chaj















Rechna


C.26
C.39
C.42
C.43
C.50
C.62
C.63
C.64
CTLD.14
CTLZ.38
CTLZ.48
CTLZ.50
CTLZ.53
CTLZ.55
CTW.31








398 The Pakistan Development Review
For consumptive use requirement of 4.0 acre feet per acre, the leaching
requirement will be about 3.0 acre feet per acre and the total water require-
ments would be about 7.0 acre feet per acre. The gypsum requirements for these
waters would be about 10 tons per acre per year in the Chaj Doab and about
6 tons per acre per year in the Rechna Doab. The cost of gypsum is estimated
as 70 rupees per ton delivered in the West Pakistan villages. For use of the
saline groundwaters, even when mixed with canal water, about 400 to 700
rupees per acre would have to be spent on gypsum every year. It is clear that
on account of extremely high gypsum requirements these waters cannot be
used for irrigation even when about 85 per cent of the pumped water has to be
used for leaching purposes and only about 15 per cent contributes to the con-
sumptive use requirements of crops.
It may be stated that above calculations are based on the experimental
work carried out in the south-western United States and in some other countries.
When similar experimental work is carried out in the Chaj and Rechna Doabs,
the actual gypsum requirements may be found to be somewhat different. How-
ever they are not likely to be so different as to make the use of soduim-rich
saline waters having more than 3000 ppm as economic.
As previously suggested by the author [5], but most forcefully put by
Dr. Eaton, provision of horizontal sub-surface drainage is the only solution
for the saline groundwater areas of West Pakistan. A basic requirement for the
use of horizontal sub-surface drainage is the provision of additional river water
to these areas. A programme for increasing the capacity of canals to divert
additional river water and installation of horizontal drainage should therefore
be initiated immediately for these areas.

The canal water supply is not likely to be adequate for all the culturable
canal commanded areas. It is, therefore, essential that canal water should be
used on the best agricultural areas already under irrigation. Out of the total
canal commanded area of about 32.8 million acres, there are some 1.5 million
acres of highly saline uncultivated or abandoned lands in the Punjab and
Bahawalpur and about 1.4 million acres in Sind [17, pp. 18 and 23]. The West
Pakistan WAPDA and Irrigation Department are engaged in the reclamation
of these soils. As will be clear from Table VI (page 369) in the report by Panel
members, installation of tubewells in the highly saline soils would cause the
good groundwaters to deteriorate 35 years earlier than installation of tubewells
in non-saline soils. It is therefore essential that no tubewells should be installed
in the highly saline soils even when these lie in good groundwater areas. Tube-
wells installed in the non-saline soils would draw down the watertable under








Ghulam Mohammad: Waterlogging and Salinity: Rejoinder


the saline soils also and the groundwater would thus be used on good soils.
Similarly no canal water should be used for the reclamation of these areas or
for the development of any other uncultivated lands. All canal waters as well
as all tubewell waters from the high quality groundwater areas should be used
only on the best agricultural lands already under cultivation.
Horizontal versus Vertical Drainage
The Panel members have enumerated 5 disadvantages of the horizontal
drainage system on pages 354 to 356 of their paper and have concluded that
horizontal drainage does not "warrant much attention...in the primary scheme
of water resources development in the Indus Plain".
The first objection of the Panel members to horizontal drainage is that
salt removed in the drainage depends largely upon the salinity of the upper
layers of groundwater. The author considers this to be the principal advantage
rather than the disadvantage of the horizontal drainage system. It is easier
to dispose of salt removed from 7 to 10 feet of the soil profile and the upper ground-
water than it is to dispose of the salt removed from 250 feet of the soil profile.
In this connectionMr. Arthur Pillsbury, Professorof Irrigationand Engineering,
University of California at Los Angeles, and Consultant to the Land and Water
Development DivisionofFAO, has stated that "the zoneofconcentration of gro-
und wateristhe root zone, and that the most efficient point to separate degraded
waters, before they become diluted is immediately below the root zone" [14,
p. 8]. Professor Pillsbury considers that this separation can be done efficiently
only with horizontal sub-surface drainage facilities [14, p. 81 and that pumping
of groundwater is completely inefficient for drainage alone [14, p. 6]. According
to Professor Pillsbury many vertical drainage schemes were started in the south-
western part of the United States beginning in the early 1920's but at present
there is not a single "drainage" well operating where the water is not used to
help irrigate the overlying land or is used to satisfy downstream water rights.
Professor Pillsbury further states that where saline waters are being pumped
an extreme corrosion and incurstation (all italics ours) problem with the well
and pump appear to be inevitable [14, p. 6].
Another point raised by the Panel members is that vertical drainage results
in a "smaller investment in conveyance channels and better salinity control
because salt can be returned to the rivers during periods of high run off or
routed to salt lagoons at times when irrigation requirement is small."
As the idea of drainage tubewells pumping into rivers during "periods of
high run off" has been recommended by the Panel members as well as by Tipton
and Kalmbach, Inc. Consultants to WAPDA, it is necessary to examine it in








400 The Pakistan Development Review
detail. By 1970, the entire flow of the Sutlej, Beas and Ravi Rivers (designated
as the Eastern Rivers in the Indus Water Treaty) will be diverted by India and
there will be no period of high run off in these rivers. No saline tubewell waters
can, therefore, be returned into the Sutlej and Ravi Rivers.

The same would be the condition of Chenab and Jhelum Rivers after a
few years. According to Mr. S. S. Kirmani, Chief Engineer, Indus Basin
Projects, West Pakistan WAPDA, "After the completion of the Indus Project,
most of the flows of the Jhelum and Chenab Rivers will be fully used in the
existing irrigation system and for the replacement of the irrigation uses on the
Eastern Rivers" [11, p. 247J. The Chenab and Jhelum Rivers will have a surplus
of only 2 to 3 MAF which will consist of erratic and infrequent flood peaks of
only a few days duration.

No drainage tubewell waters from any part of the Punjab can therefore
be returned to any river during the "period of high run off" because there will
be no period of high run off after 1975. If canal capacity is increased and more
river water is diverted on to lands as suggested earlier in this paper, there may
not be any period of high run off after 1970.
The Indus is the only river in which some 35 MAF will continue to flow
to the sea during the period of high run off but topography does not permit
drains in any area in the Punjab part of the Indus Plain to outfall to the Indus
River. Drainage waters from the lower part of the Bahawalpur and Sind could
be returned to the Indus during the period of high run off, but that would
damage the agriculture in Lower Sind, slowly but certainly. As pointed out
by Dr. Eaton (p. 382), the longevity of agriculture which supports many millions
of people should be viewed in terms of centuries rather than on the basis of
an expedient which may suffice for only a limited number of years. Alexander
Karpov has pointed out there are millions of acres in North Africa and Western
Asia where great cultures once flourished. At present nothing is left but sand
dunes, salt marshes and eroded landscapes [10, p. 2271. The proposals of Panel
members and of Tipton and Kalmbach would similarly convert the Indus
Valley agricultural areas into barren salty lands.

The Panel members have also proposed disposal of saline pumped waters
into desert lagoons. This is possible for Bahawalpur and parts of Sind, but un-
fortunately there are no desert lagoons in the Rechna and Chaj Doabs where
large quantities of pumped waters from the highly saline groundwater areas of
these doabs could be disposed off. The conclusion is therefore inescapable that
there is no place for disposalof pumped water from the highly saline groundwater
areas inthe Punjab. These must remain where they're. Saltfrom theupper 7to 10








Ghulam Mohammad: Waterlogging and Salinity: Rejoinder 401
feet of the soil profile only should be removed by horizontal drainage. This
would be small and can be disposed of in on-farm evaporation flats as sugges-
ted Dr. Eaton (pp. 384-385) or in larger evaporation flats at the lower end of each
doab as previously suggested by the author [5, pp. 394-95].
The Revelle Report also recommended "the use of salt tolerant crops"
in areas where saline groundwaters are to be used [18, p. 991. Tipton and
Kalmbach are again proposing "basic changes in the agriculture" of West
Pakistan and the introduction of "new crops" in saline groundwater areas.
The author would like to point out that introduction of "new crops" does
not lessen the soil salinity brought on the land by the saline waters. The people
of the Tigris-Euphrates Valley tried this method to stave off the effect of salt;
they replaced wheat with barley, which is more salt tolerant. That helped
temporarily, but the salt content continued to increase and the civilization
declined and passed away [10, p. 2411. The same thing would happen to West
Pakistan if it tried to introduce new salt tolerant crops proposed by the Panel
members and by Tipton and Kalmbach, instead of solving the basic problem
of the removal of salt from the irrigated areas by the provision of horizontal
sub-surface drainage facilities.
The second objection of the Panel members regarding flat topography
and cost of horizontal drains has been discussed at length by the author in a
previous issue of this Review [5, pp. 388-3941. Calculations made by Dr. Mushtaq
Ahmad, Director, irrigation Research Institute, Lahore, indicate that the natural
slope of the country is more than adequate for the slopes required for seepage
drains in West Pakistan [13, pp. 10-561.

The third objection of the Panel members is that open drain systems occupy
a significant portion of land area inbetween the cultivated fields and hence
cause the farming operation to be spread out on more land. This objection is
not valid for West Pakistan, where the canals have already been laid out.
Actually, in a considerable part of the Punjab, shallow main drains have already
been constructed. Mr. C. R. Maierhofer, Chief, Division of Drainage and
Groundwater Engineering of the United States Bureau of Reclamation, considers
that deep drains should be constructed where these shallow drains are located
[12, p. 14].
The fourth objection of the Panel members that deep main drains and
open field drains are difficult to maintain is somewhat more telling. For this
reason, field drains are generally covered. The cost of maintenance of tile drains
is very low [12, p. 161. The large collector drains and main drains are generally
open. They have to be maintained in efficient condition just as canals are main-








402 The Pakistan Development Review

trained in efficient condition. The removal of weeds and debris and repair of
side slopes is far more economical than the operation, maintenance, and frequent
replacement of corroded and incrusted tubewells in saline groundwater areas
in any country of the world, but more so in a country like Pakistan where
labour is underemployed and unemployed.
The fifth objection of the Panel members regarding the public health
hazard of stagnant water and swampy reaches of open drains would be valid
only if the drains were not properly maintained. There is no point in construct-
ing the drains if these are not to be properly maintained. When properly main-
tained there is no public health hazard.
Role of Public and Private Tubewells
The Panel members consider that government tubewells are better than
private tubewells for the following reasons:
1) Government tubewells are somewhat more economical than private
tubewells (pp. 339-340 and Table IV).
2) Government tubewells can be more easily integrated with canal
operations than private tubewells (pp. 340-341).
3) Government tubewells can be used for reclamation of saline soils and
the underground reservoir can be used for storage of salt flushed out
of root zone (pp. 342 and 350).
4) Government tubewells are better adapted for the exploitation of poor
quality and sodium-rich groundwaters which can be used by mixing
with Canal water (p. 342).
5) Government tubewells are better adapted for control of lateral migra-
tion of salinity. (p. 342).
6) Government tubewells are better than private tubewells on account
of their social effects (pp. 342-343).
The author considers that it is not necessary to have government tubewells
for any of the above reasons:
1) In calculating the cost of pumping water from government and private
tubewells, the Panel members have used full cost of the private tubewells but
only part of the cost of government tubewells. The total cost of a private tube-
well (of 1.25 cusec capacity) to the economy was estimated as 7,800 rupees by
the author, whereas cost of the government tubewell (of 3.9 cusec capacity) to
the economy was estimated as 79,700 rupees by WAPDA [4, p. 255]. In Table IV
of their paper, the cost of project preparation, cost of equipment required for
drilling government tubewells, cost of government staff, fee to be paid to the
contractors engaged after international bidding, contingencies, and interest








Ghulam Mohammad: Waterlogging and Salinity: Rejoinder 403
during the period of construction all amounting to 27,800 rupees for each 3.9
cusec tubewell have been ignored by the Panel members. Furthermore, the life of
government tubewell has been taken as double that of private tubewells for
which there is no justification [4, pp. 238-39]. (see also, Table I on p. 372).

The author has included the full cost of government tubewells and re-
calculated cost of pumping water in Table IV of the report of the Panel members,
assuming life of both tubewells to be 10 years. On this assumption the cost
of pumping water from government tubewells comes out to be 44per cent higher
than private tubewells when the load factor is assumed as 25 per cent. However,
government tubewells have been worked on a load factor of over 50 per cent. If
this is adopted, the cost of pumping water from government tubewells is equal
to that from private tubewells.
2) There is no reason why farmers will not integrate the working of private
tubewells with the working of canals. Already the farmers of Gujranwala and
Sialkot districts where canal water is supplied only during the kharif season are
integrating the working of private tubewells with the canal water and have
attained the highest intensity of cropping [6, p. 26]. It is simple: the
moment, the canal is closed, the farmers switch on the tubewells. Dissemination
of information about canal closures is good but is not absolutely necessary.

3) As already pointed out, all canal water and tubewell water should be
used on the best agricultural lands already under cultivation and not on re-
clamation of highly saline soils. Such reclamation by government tubewells will
only deteriorate the quality of groundwater by adding salts leached down from
the soil profile.
4) As previously stated saline and sodium-rich groundwaters should not
be pumped at all. They would increase water supply but would cause deter-
ioration of soil and reduce the total agricultural production in the country.

5) The centrifugal pumps used by the farmers have a maximum draw down
of about 20 to 25 feet. With private tubewells located in the upper reaches of the
doabs and lowering the watertable to about 20 feet, and with drains lowering
the watertable to about 7 to 10 feet in the saline areas, there is no danger
of contamination of non-saline groundwaters with infiltration from saline ground-
water areas. On the other hand, there would be some danger with government
tubewells pumping water to 100 feet depth in non-saline areas and to 50 feet
depth in the saline areas as proposed by the Panel members.
6) In all areas where an adequate number of tubewells has been installed,
the price charged by tubewell owners varies from 2.5 to 3.5 rupees per hour








404 The Pakistan Development Review

whereas the cost of operation of tubewells comes to about 1.2 to 2.6 rupees
per hour [6, pp. 17-181. With additional tubewells being installed every year,
the price charged by owners is being reduced year by year. No government
regulation on the price of tubewell water, as proposed by the Panel members,
is necessary.

Some of the major points in favour of private tubewells are the following:
First, the private tubewells mobilize domestic resources and thus increase the
total size of the development programme to that extent. A greater increase
in agricultural production in West Pakistan would result if the farmer's re-
sources are used for installation of tubewells and government resources are
used for increasing the fertilizer manufacturing capacity and for electric trans-
mission and distribution facilities than if government resources are used for
drilling of tubewells. Secondly, foreign exchange required for private tubewells
is very small whereas the foreign exchange component of government tubewells
approximates 58 per cent of the total cost.3. If an appropriate "shadow price",
say 7 rupees to a dollar is used for foreign exchange, the cost of government
tubewells increases by approximately 27 per cent. The cost of pumping water
from government tubewells then becomes 67 per cent higher than those from
private tubewells when the load factor is the same. When government tubewells
work twice the number of hours compared to private tubewells, the cost of
pumping water is 14 per cent higher in these when foreign exchange is app-
ropriately valued. Thirdly, private tubewells contribute to the development of
local industry such as diesel engines, electric motors, drilling rigs, and other
manufacturing capacity. The government tubewells damage the established
manufacturing industries by importing the same equipment, goods and services
from abroad. Finally, the private tubewells not only mobilize domestic resources
but also develop a strong class of highly energetic farmers who act as leaders
in modernizing agriculture in the country. The government tubewells depend
upon tied foreign loans obtained with high rates of interest, increase the foreign
debt of the country and stifle the energetic class of farmers by destroying their
previously installed tubewells and installing expensive government tubewells
instead.
Concluding Remarks
The system of tubewell installation for irrigation and drainage purposes as
recommended by the Revelle Panel and by Tipton and Kalmbach and that being
followed by West Pakistan WAPDA is a temporary expedient and a self-destruc-
3 Total cost of tubewells (excluding electrification and drainage facilities) in SCARP
3 is estimated as 123.5 million rupees, out of which 71.8 million rupees (15.1 million dollars)
are required in foreign exchange for equipment, goods and services that must be imported [16,
p. 48].








Ghulam Mohammadi Waterlogging and Salinity: Rejoinder 405
tive system. The saline groundwaters being pumped or proposed to be pumped
can neither be used in the same area nor can they be passed on to downstream
users without acceptance of ultimate desolation. The salts must be removed
from the irrigated areas by a permanent horizontal sub-surface drainage system
and the saline waste disposed of in evaporation flats in the Upper Indus Plain
and conveyed to the sea through special canals in the Lower Indus Plain.

A basic problem in the irrigated agriculture of West Pakistan is the deficiency
of water supply to meet the consumptive use requirements of crops and to
leach down the salts. This deficiency is being made good by the farmers in the
non-saline groundwater areas with the installation of private tubewells. The gov-
ernment must increase the capacity of canals and divert additional river water
on to the best agricultural lands in the saline groundwater areas and initiate
a programme for the construction of subsurface drainage facilities.
Reclamation of saline soils even in high quality groundwater areas would
cause the groundwater to become unfit for use due to leaching down of salts.
No canal or tubewell water should therefore be used for such reclamation.
Similarly no canal or tubewell water should be used for the development of
marginal lands and all available water supplies should be used on the best
agricultural lands already under cultivation.

REFERENCES

1. Asghar A.G. and Nazir Ahmad, "Drainage or Irrigated Soils in Arid Re-
gions", Proceedings of the Punjab Engineering Congress, Vol. XXXIX, 1955.

2. Ahmed, Nazir, and Mohammad Akram, Evapo-Transpiration as a Func-
tion of Depth to Watertable and Soils. (Lahore: Irrigation Research Insti-
tute, 1965).

3. Bower, C.A., and M. Maasland, "Sodium Hazard of Punjab Groundwaters"
Symposium on Waterlogging and Salinity in West Pakistan. (Lahore: West
Pakistan Engineering Congress, October 1963).

4. Ghulam Mohammad, "Some Strategic Problems in Agricultural Develop-
ment in Pakistan", Pakistan Development Review, Vol. IV, No. 2, Summer
1964.

5. "Waterlogging and Salinity in the Indus Plaint A
Critical Analysis of Some of the Major Conclusions of the Revelle
Report", Pakistan Development Review, Vol. IV, No. 3, Autumn 1964.








The Pakistan Development Review


6. "Private Tubewell Development and Cropping
Pattern in West Pakistan", Pakistan Development Review, Vol. V, No. 1,
Spring 1965.
7. Gilani, Maqsood Ali Shah, and Abdul Hamid, Quality of Ground Water,
Chaj Doab. Mimeographed. (Lahore: Water and Soils Investigation Divi-
sion, West Pakistan WAPDA, August 1960).

8. Greenmen D.W., W.V. Swarzenski and G.D. Bennet, The Groundwater
Hydrology of the Punjab. (Lahore: Water and Soil Investigation Division,
West Pakistan WAPDA, 1963).

9. Harza Engineering Company International, Programme for Water andPower
Development in West Pakistan Through 1975. (Lahore: Harza Engineering
Company, January 1964).
10. Karpov, Alexander V., "Indus Valley-West Pakistan's Life Line", Journal
of the Hydraulics Division, (Proceedings of the American Society of Civil
Engineers), Vol. 90, No. HY 1, January 1964.

11. Kirmani, S.S., "Indus Valley, West Pakistan's Life Line: Discussion",
Journal of the Hydraulics Division, (Proceedings of the American Society
of Civil Engineers), Vol. 90, No. HY 5 September 1964.
12. Maierhofer, C.R., Report on Drainage Requirements For Irrigated Areas
of West Pakistan. Mimeographed. (Denvor. Tipton and Kalmbach Inc.,
April 1957).
13. Mushtaq Ahmad and Abdur Rehman ,"Design of Alluvial Channels As
Influenced by Sediment Charge", Proceedings of West Pakistan Engineering
Congress, 1962. (Lahore: West Pakistan Engineering Congress, 1962).
14. Pillsbury, Arthur F., Principles in the Utilization of Flood Plains.
Paper presented at the Seminar on waterlogging and Salinity sponsored
by FAO and the Government of Pakistan. Lahore, November 1964.
Mimeographed. (Rome: FAO 1965).
15. Shamsi, R.A. and Abdul Hamid, Quality of Groundwater, Rechna Doab,
Mimeographed. (Lahore: Water and Soils Investigation Division, West
Pakistan WAPDA, August 1960).
16. Tipton and Kalmbach, Feasibility Reporton Salinity ControlandReclamation
Project Number 3, Lower Thal Doab. (Denvor Tipton and Kalmbach, April
1963).









Ghulam Mohammad: Waterlogging and Salinity Rejoinder 407
17. West Pakistan WAPDA, Summary of Basic Report on Waterlogging and
Salinity in West Pakistan. Prepared for the Seminar on Waterlogging and
Salinity sponsored by FAO and Government of Pakistan. Mimeographed
(Rome: FAO, 1964).
18. White House-Department of Interior Panel on Waterlogging and Salinity
in West Pakistan, Report on Land and Water Development in the Indus
Plain. (Washington, D.C.: Supdt. Doc. January 1964). This report is re-
ferred to as the Revelle Report in this paper





































































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