Front Cover
 Title Page
 Table of Contents
 Summary and discussion
 Literature cited

Title: Emergy analysis perspectives public policy options, and development guidelines for the coastal zone of Nayarit, Mexico. Volume 2: Emergy analysis and public policy options
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Permanent Link: http://ufdc.ufl.edu/UF00016672/00001
 Material Information
Title: Emergy analysis perspectives public policy options, and development guidelines for the coastal zone of Nayarit, Mexico. Volume 2: Emergy analysis and public policy options
Physical Description: Book
Language: English
Creator: Brown, Mark T.
Green, Paul
Gonzalez, Agustin
Venegas, Javier
Publisher: Center for Wetlands and Water Resources, University of Florida
Publication Date: 1992
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Volume ID: VID00001
Source Institution: University of Florida
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Resource Identifier: notis - AAA9289

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Table of Contents
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Full Text


Report to
The Cousteau Society
and the
Government of Nayarit, Mexico

EmergyAnalysis and Public Policy


Mark T. Brown
Pamela Green, Agustin Gonzalez, and Javier Venegas

September, 1992

Center for Wetlands and Water Resources
University of Florida
Phelps Lab, Museum Road
Gainesville, Florida
Tel (904) 392-2424 Fax (904) 392-3624


Report to
The Cousteau Society
and the
Government of Nayarit, Mexico

Volume 2: EMergy Analysis and Public Policy Options


Mark T. Brown, Pamela Green, Agustin Gonzalez, and Javier Venegas

Research Studies Conducted Under Contract No. 90071109

September, 1992

Center for Wetlands and Water Resources
University of Florida
Phelps lab, Museum Road
Gainesville, Florida
Tel. (904) 392-2424 Fax (904) 392-3624


Volume 2: EMergy Analysis and Public Policy Options


INTRODU CTION ............................................................... 1-1
Background .................................. ........................ .. .... 1-1
Ecological Econom ics .......................................................... 1-2
Public Policy and Issues of Resource Use ............................................ 1-2
Theory of Maximum EMergy Designs ............................................... 1-3
EMergy, W health and Value ................................................ ..... 1-3
Plan of Study ............................. ............. .... .... ... .......... 1-5

M ETH OD S .......................... ................... ..... ..................... 2-1
Definitions .................................. ..... ......... ............ 2-1
Step 1: Overview System Diagrams ............................................... 2-2
Step 2: EMergy Analysis Tables .................................................. 2-2
Step 3: Calculation of EMergy Indices .................... .......... ............. 2-3
Criteria for Alternative Public Policies ............................................... 2-6
Analysis of Public Policy Options ............... .... ............................. 2-7

RESU LTS ................................................... .. ..... .. .............. 3A-1
EM ergy Analysis of M exico ..................................................... 3A-1
EM ergy Analysis of Nayarit ..................................................... 3B-1
EMergy Analysis of Banderas Basin and Water and Wastewater Options .................... 3C-1
EM ergy Analysis of Tourism ......................................... ............ 3D-1
EMergy Analysis of Mariculture and Fisheries ........................ .............. 3E-1
EMergy Analysis of Public Health Options ............... ........................ 3F-1

SUMMARY AND DISCUSSION ................. ........................... ....... 4-1
General Statement of Project Objectives ................ ...... ...................... 4-1
The Basis for Wealth in Mexico, Nayarit, and the Banderas Basin ........................... 4-1
Tourism Development, Environmental Impact, and the Local Economy ....................... 4-5
Options and Management of Water and Wastewater in the Coastal Zone of Nayarit ............. 4-9
Mariculture and Fisheries in the Coastal Zone of Nayarit .............................. 4-10
Rural Health Options in the Coastal Zone of Nayarit ................... ............. .. 4-12
Summary and Recommendations ....................................... .. .......... 4-13
C conclusion ................................................................. 4-15

LITERATURE CITED ........... .... .. ..................... ........................ 5-1


Volume 2: EMergy Analysis and Public Policy Options

Mark T. Brown, Pamela Green, Agustin Gonzalez, and Javier Venegas


This document is the second of a two volume report to The Cousteau Society and the Government of the
State of Nayarit, Mexico (see Figure 1). It is an outgrowth of a 2-year study to develop a master plan for the coastal
zone of Nayarit. As part of our effort, we developed a recommended Master Plan, comprised of a complete set of
planning documents that included a map of Overall Development Potential, a regulatory framework, and the
necessary legislation for implementation (given in Volume 1). In addition to the planning documents, the research
team conducted EMergy analysis studies of fisheries, tourism, water use, and health care within the coastal zone.
These studies provided the necessary background information for public policy decisions regarding the best use of
resources and for determining carrying capacity of the coastal zone for future development. As part of our efforts,
two Mexican students were trained in the methods of EMergy analysis and environmental planning.
This volume is composed of the results of our studies. While there are many aspects of the coastal zone
and its environment and cultural systems that should be studied, time and resources dictated that only a few of the
most important resource questions be addressed. In addition to the analysis of the Mexican economy and that of the
State of Nayarit (that were necessary for background data), we selected the four areas listed above, which we felt
would provide needed information for developing a strong and coherent proposed Master Plan.


In July of 1990, The Cousteau Society received funds from the Governor of the State of Nayarit, Mexico
for studies of the coastal resources of the State, with the ultimate goal of developing a proposed Master
Development Plan. Nayarit was beginning to experience growth of populations and tourist facilities within its coastal
zone, and wisely felt the need to protect and enhance its resources and foster environmentally compatible
development. The Cousteau Society and a team of researches from the Center For Wetlands and Water Resources
at the University of Florida embarked on a two-year effort to develop a proposed Master Development Plan for the
coastal zone that would protect the cultural and environmental resources of Nayarit. The work effort was composed
of two aspects: a research effort to apply techniques of EMergy analysis to questions of resource use, and a parallel

Figure 1. Location map of the State of Nayarit, Mexico and its coastal zone (shaded area).

effort to develop a proposed Master Plan. The results of the EMergy analysis formed a basis for recommending
wise resource use and, ultimately, for determining carrying capacity for human populations and tourism within the
coastal zone.

Ecological Economics

Among the most important problems facing humanity today are the sound management of natural
resources and development of procedures for the integrated study of human and non-human processes. Increasingly,
there is a need to understand both of these domains, each in the context of the other, and to develop management
strategies which acknowledge and promote the vital interconnections between the two. Neither economics nor
ecology alone adequately address the problems world society presently faces. Questions regarding optimizing
resource use, managing equitable international trade, over-exploitation of resources, loss of biotic diversity, or global
climate change cannot be solved by focusing on isolated aspects of a larger problem. A wider view is necessary: one
that combines the systems of humanity and nature and that does not treat the affairs of humans and the productive
processes of the biosphere as distinct entities; the one having domain over the other. A new paradigm for such an
analysis is emerging. Just as the separate and distinct economies of individual nations are becoming increasingly
interwoven into a worldwide economic system, it is becoming quite apparent that economic well-being and ecologic
stability depend upon developing an interface between ecology and economics. We call this interface "ecological
economics" and the tool we use to quantitatively evaluate the interface is "EMergy Analysis"
This study uses techniques of EMergy analysis to evaluate both traditional economic variables and ecologic
systems (Odum 1978, 1988). This method evaluates--on a common basis--the main driving energies of the economy,
and the requirements and contributions of individual development projects. Included are economic goods and
services, fuels, and the fluxes of renewable energies, as well as environmental changes that occur, such as the loss of
terrestrial production. EMergy analysis allows comparison and incorporation of environmental costs and benefits
with variables of traditional economic costs and benefits to provide a more comprehensive perspective for policy

Public Policy and Issues of Resource Use

The interface of ecology and economics is most often found in the marketplace. Resources are exploited
and sold, and in the process the environment sustains some transformations. Questions of how best to manage a
nation's resources, how to develop them, extract them, and whether they should be exported in exchange for other
needed resources are public policy questions. Until very recently, public policy was most often determined almost
wholly within an economic framework, most commonly within the limited context of market transformations. Yet
economic considerations often do not reflect ecologic realities, societal needs, environmental impacts, or
sustainability of natural resources because these things are generally outside the realm of individual human
preferences or the ability of markets to provide adequate information.

Theory of Maximum EMergy Designs

A new public policy value system is required -- one that can recognize the differences between short-term
individual human preference and long-term macroscopic economic well-being, and that can quantitatively determine
value at the macroscopic scale of society and environment. Decisions regarding use of resources ultimately impact
on the well-being of the entire citizenry, and as a result, the process of decision making should focus on determining
which alternatives and options will have the greatest positive impact on well-being. We believe that public policy
decisions should be based on the principle that the alternative that maximizes EMergy is the preferred choice.
Theory suggests (Odum 1971, 1983; Odum and Odum 1983) that economies of nature and humans organize
so as to develop the maximum EMergy possible; and that in so doing they prevail and are sustained over
alternatives. The theoretical basis is found in the Maximum Power Principle (Lotka 1922a,b, and 1945). To
maximize power, an economy develops an organization of useful processes that increases total production through
positive feedback and by overcoming limiting factors. Economies, in the long run, cannot prevail in competition with
others if EMergy is wasted in nonproductive processes; yet in the short run, one can observe apparent
contradictions. However, since observations of any system are time dependent, the real issue is not that processes
exist that seem to "waste" EMergy (i.e., do not reinforce productive processes) and thus violate the maximum power
principle, but whether they can do so indefinitely in a competitive environment where selective processes are geared
to eliminate them. This view is in contradiction to some economic theories that suggest any expenditure of money
and resources leads to economic vitality, whether or not it is for unnecessary products or services.
Many scientists are used to thinking of systems as organizations of processes that are sustained by their
driving energies and resources, and that competition and competitive exclusion are the means by which systems self-
organize and develop sustainable patterns. Yet few believe that the criterion for survival, or sustainability, is
maximum EMergy or that competition and competitive exclusion are selective processes that operate to maximize
EMergy. Other criteria for survival that have been suggested include: minimum cost, minimum risk, maximum
stability, maximum efficiency, maximum production, least work, and maximum diversity, among others. The
viewpoint used in the present study is that economies, and processes within economies, organize and operate so as to
increase real wealth and prevail according to the maximum EMergy principle; and that a measure of real wealth is

EMergy, Wealth and Value

EMergy is a quantitative measure of the resources required to develop a product (whether a mineral
resource that results from bio-geologic processes, a biologic resource such as wood, or an economic product that
results from industrial processes) and express the required resources in units of one type of energy (usually solar).
We suggest that evaluations using EMergy may help to clarify policy options, because the use of EMergy as a
measure of value overcomes four important limitations of previous attempts to quantify environmental impacts,
development cost/benefits, and alternative technologies. These limitations are as follows: (1) Mixing units of

measure such as weight, volume, heat capacity, or economic market price cannot lead to comparative analysis. The
relative contribution to a nation's economic vitality derived from fossil fuels (measured in barrels), sunlight
(measured in ergs), and phosphorus in fertilizers (measured in kilograms) is difficult to determine. (2) Evaluations
that use the heat value of resources for quantification assume that the only value of a resource is the heat that is
derived from its combustion. In this way, for example, human services are evaluated as the calories expended doing
work, and when compared to other inputs to a given process are several orders of magnitude smaller and often
considered irrelevant. (3) Unmonied resources and processes (i.e., those outside the monied economy) are often
considered externalities and are thus not quantified. Most processes, and all economies, are driven by a combination
of renewable and nonrenewable energies. Renewable energies (sunlight, rain, wind, tides, etc.) are outside the
monied economy and therefore are generally not accounted for in economic evaluations. Yet they are absolutely
necessary in all economies and make up a large portion of most products. Economic vitality depends on the
successful use of available resources, both renewable and nonrenewable (fuels, mineral resources, and the goods
derived from them); thus, evaluations that leave out renewable energies because they are externalities consistently
"undervalue" the total production in economies and environmental processes. (4) Price determines value. The price
of a product or service reflects human preferences often called "willingness-to-pay." It can also reflect the amount of
human services "embodied" in a product. A valuing system based on human preference assigns either relatively
arbitrary values or no value to necessary resources or environmental services.
EMergy is a measure of the real wealth of an economy (Odum 1984; Odum and Arding 1991). Since
wealth is ultimately tied to resources, it is necessary to express wealth in units that reflect the resource base.
Conditioned as we are that price reflects value, we often believe that money is the measure of wealth and that price
determines value. Price suggests what humans are willing to pay for something; but value to the public is
determined by the effect a resource has in stimulating an economy. For instance, a gallon of gas will power a car
the same distance no matter what its price; its value to the driver is the number of miles (work) that can be driven.
Its price reflects the scarcity of gasoline and how important it is to do the work. Price is often inverse to a
resource's contribution to an economy. When a resource is plentiful, its price is low, yet it contributes much to the
economy. When a resource is scarce its total contribution to the economy is small yet its price is high.
EMergy may be a measure of the equivalence when one resource is substituted for another. Sunlight and
fossil fuels are very different energies; yet when their heat values are used the difference is not elucidated. A joule
of sunlight is not equivalent to a joule of fossil fuel in any system other than a heat engine. In the realm of the
combined system of humanity and nature, sunlight and fuels are not equally substitutable, joule for joule. However,
when a given amount of fuel energy is expressed as solar EMergy, its equivalence to sunlight energy is defined.
Since EMergy is a measure of the work that goes into a product, expressed in units of one type of energy (sunlight),
it is also a measure of what the product should contribute in useful work in relation to sunlight.
We recognize the difficulty that these concepts present since they use new terminology and a different
measure of value from those in common usage. However, the concept of value and national wealth stemming from
resources is not new, but is as old as economics itself. The history of economic thought is replete with considerable
discussion and analysis of national wealth as measured by resources and by attempts to measure value as it stems

from resource use. Only recently has economic theory been dominated by the determination of value based on price
and national wealth measured by currency. During times of resource scarcity, economic values were related most
often to resources (land, labor or energy) and resource use; but during times of resource abundance, economic
values were related most often to currency and price.
The failing of previous theories of resource-based value, and most current ones as well, has been that they
did not account for different types of energy, but assumed that the heat value of energy was a common denominator
by which quantification and comparisons could be made. We believe this to be incorrect. All energy types are not
equivalent in their ability to do work; and, without accounting for the differences in what has been termed the
quality of different types of energy, erroneous conclusions can result. Use of EMergy to represent all the
contributions to any given product or process accounts for differences in resource quality and expresses different
resources in equivalent capacity to do work.

Plan of Study

The studies contained in this volume are part of a larger study to develop a proposed Master Plan for the
state of Nayarit, Mexico. Since a Master Plan focuses on the physical use of lands and waters, we felt it necessary to
provide additional studies of important aspects of the economy that are not normally addressed in a Master Plan.
These studies, then, were undertaken to provide background information from which public policy related to
resource use and sustainable development might be better focused. They provide a quantitative framework from
which policy can be decided. While there are numerous issues and environmental concerns that could be studied,
we focused on four areas:

1. Tourism and its impacts on local economies, environments and social systems
2. Water use, and potentials for reuse
3. Coastal fisheries, mariculture, and options for protein production
4. The current public health system

Everything is part of a system, and systems are composed of interrelated units. Each of these four areas
were studied as a whole and as a subsystem of the next larger system in order to understand how they fit together.
To accomplish this, it was necessary to also conduct EMergy evaluations of the economy of Mexico, the State of
nayarit, and the Banderas Basin. This "top-down" approach facilitates a better understanding of subsystems and the
public policy issues that surround them. Decisions regarding the exploitation of natural resources almost invariably
require the integration of both economic and ecologic concerns. All too often policy decisions on the local level are
made without sufficient information concerning the implications to the next larger system level. The reverse is also
true; decisions made at the regional or national level have serious impacts on local economies and resource systems.
The hierarchical systems approach presented in these studies lends insight and allows for the public policy decision
process to integrate both the economic and ecologic implications of management alternatives.


This section gives general methods of EMergy analysis for the evaluations that follow in the Results
sections. The general methodology for EMergy analysis is a "top-down" systems approach. The first step is to
construct systems diagrams that are a means of organizing thinking and relationships between components and
pathways of exchange and resource flow (systems symbols and brief definitions are given in Figure 2). The second
step is to construct EMergy analysis tables directly from the diagrams. And the final step involves calculating several
EMergy indices that relate EMergy flows of the economy with those of the environment, and allow the prediction of
economic viability and carrying capacity. Additionally, using the results of the EMergy analysis tables, comparisons
between the EMergy costs and benefits of proposed developments as well as insights related to international flows of
money and resources are made. Before presenting detailed descriptions of each step in the methodology, definitions
are given for several key words and concepts.


Energy. Sometimes referred to as the ability to do work, energy is a property of all things which can be turned into
heat, and is measured in heat units (BTUs, calories, or joules).

EMergy. EMergy is an expression of all the energy used in the work processes that generate a product or service, in
units of one type of energy. Solar EMergy of a product is the EMergy of the product expressed in
equivalent solar energy required to generate it. Sometimes it is convenient to think of EMergy as Energy

EMjoule. The unit of measure of EMergy ("EMergy joule"), it is expressed in the units of energy previously used to
generate the product. For instance, the solar EMergy of wood is expressed as joules of solar energy that
were required to produce the wood. Solar EMjoules is abbreviated "sej".

EMpower. The flow of EMergy per unit time; expressed as sej/time.

EMpower density. EMpower per unit area; units are sej/time/area.

Macroeconomic dollar. This is a measure of the money that circulates in an economy as the result of some process.
In practice, to obtain the macroeconomic dollar value of an EMergy flow or storage, the EMergy is
multiplied by the ratio of total EMergy to Gross National Product for the national economy.

Nonrenewable Energy. Energy and material storage like fossil fuels, mineral ores, and soils that are consumed at
rates that far exceed the rates at which they are produced by geologic processes, are nonrenewable

Renewable Energy. Energy flows of the biosphere that are more or less constant and reoccurring, and which
ultimately drive the biological and chemical processes of the earth and contribute to geologic processes, are
renewable energies.

Resident Energy. Resident energies are the renewable energies that are characteristic of a region.

Transformity. The ratio obtained by dividing the total EMergy that was used in a process by the energy yielded by
the process, transformity has the dimensions of EMergy/energy (sej/J). A transformity for a product is
calculated by summing all the EMergy inflows to the process and dividing by the energy of the product.
Transformities are used to convert energies of different types to EMergy of the same type. Given next is
further elaboration on the methods used for EMergy analysis.

Step 1: Overview System Diagrams
A system diagram in "overview" is drawn first to put in perspective the system of interest, combine
information about the system from various sources, and to organize data gathering efforts. The process of
diagramming the system of interest in overview ensures that all driving energies and interactions are included. Since
the diagram includes both the economy and environment of the system, it is like an impact diagram which shows all
relevant interactions.
Next, a second simplified (or aggregated) diagram, which retains the most important essence of the more
complex version is drawn. This final, aggregated diagram of the system of interest is used to construct a table of
data requirements for the EMergy analysis. Each pathway that crosses the system boundary is evaluated.

Step 2: EMergy Analysis Tables
EMergy analysis of a system of interest is usually conducted at two scales. First, the system within which
the system of interest is embedded is analyzed and indices necessary for evaluation and comparative purposes are
generated. Second, the system of interest is analyzed. Both analyses are conducted using an EMergy Analysis Table
organized with the following headings:

1 2 3 4 5 6
Note Item Raw Units Transformity Solar Macro-
EMergy economic $

Each row in the table is an inflow or outflow pathway in the aggregated systems diagram; pathways are evaluated as
fluxes in units per year. An explanation of each column in an EMergy Analysis Table is given next.

Column 1 The line number and footnote number that contains sources and calculations for the
Column 2 The item name that corresponds to the name of the pathway in the aggregated systems
Column 3 The actual units of the flow, usually evaluated as flux per year. Most often the units are
energy (joules/year), but sometimes are given in grams/year or dollars/year.
Column 4 Transformity of the item, usually derived from previous studies.
Column 5 Solar EMergy (sej), which is the product of the raw units in Column 3 with the
transformity in Column 4.
Column 6 The result of dividing solar EMergy in Column 5 by the EMergy to money ratio
(calculated independently) for the economy of the nation within which the system of
interest is embedded.

Step 3: Calculation of EMergy Indices
Once the EMergy analysis tables are completed, several indices using data from the tables are calculated to
gain perspective and aid in public policy decision-making. The principles used in judging development alternatives
are as follows: (1) When alternative investments are compared, the investment that contributes the most EMergy
value to the public economy in the long run is most likely to be successful; and (2) when a single system is analyzed,
the EMergy intensity of the development should match that of the local economy. Two ratios are calculated:
EMergy Investment Ratio (IR), and the Environmental Loading Ratio (ELR). Several other indices help in gaining
perspective about processes and are necessary precursors to the IR and ELR; they are: EMergy/Money Ratio,
EMergy Per Capita, EMergy Density, EMergy Exchange Ratio, Net EMergy Yield Ratio, and Solar Transformity.
These are defined as follows:

EMergy/money ratio is the ratio of total EMergy flow in the economy of a region or nation to the GNP of the
region or nation. The EMergy/money ratio is a relative measure of purchasing power when the ratios of
two or more nations or regions are compared.

EMergy per capital is the ratio of total EMergy use in the economy of a region or nation to the total population.
EMergy per capital can be used as a measure of average standard of living of the population.

EMergy density is the ratio of total EMergy use in the economy of a region or nation to the total area of the region
or nation. Renewable and nonrenewable EMergy densities are also calculated separately by dividing the
total renewable EMergy by area and the total nonrenewable EMergy by area, respectively.

EMergy exchange ratio is the ratio of EMergy exchanged in a trade or purchase (what is received to what is given).
The ratio is always expressed relative to one or the other trading partners and is a measure of the relative
trade advantage of one partner over the other. Figure 3a shows the relationship and calculation of the
EMergy exchange ratio.

Net EMergy yield ratio is the ratio of the EMergy yield from a process to the EMergy costs. The ratio is a measure
of how much a process will contribute to the economy. Primary energy sources have yield ratios in the
range of 3:1 to as high as 11:1; thus, they contribute much to the wealth of the economy. Figure 3b shows
the method of calculating the net EMergy yield ratio.

Solar transformitv is the ratio of the actual energy in a product or service to the solar EMergy that is required to
generate it; its units are sej/J. The transformity is a measure of the "value" of a service or product, with the
assumption that systems operating under the constraints of the maximum EMergy principle (Odum and
Arding 1991) generate products that stimulate productive processes which generate at least as much as
value as they cost. Figure 3c shows the method of calculating a transformity.

Determining the Intensity of Development and Economic Competitiveness: EMergy INVESTMENT RATIO
Given in Figure 4 is a diagram illustrating the use of nonrenewable and renewable EMergies in a regional
economy. The interaction of indigenous EMergies (both renewable [I] and nonrenewable [N] with purchased
resources from outside [F]) is the primary process by which humans interface with their environment. The
Investment Ratio (IR) is the ratio of purchased inputs (F) to free EMergies derived from local sources (the sum of I
and N) as follows:

IR = F/(I+N) (1)

The name is derived from the fact that it is a ratio of "invested" EMergy to resident EMergy. The
Investment Ratio is a dimensionless number; the bigger the number the greater the amount of purchased EMergy
per unit of resident EMergy. Comparison between a regional IR and the ratio for a proposed development may be
used as an indicator of the intensiveness of the development within the local economy. When the ratios of two
developments of the same kind are compared, an indication of their economic competitiveness is derived. The
Investment Ratio can also be used to indicate if a process is economical in its utilization of purchased inputs in
comparison with other alternative investments within the same economy.

Determining Environmental Impact: ENVIRONMENTAL LOADING RATIO
Nearly all productive processes of humanity involve the interaction of nonrenewable EMergies with
renewable EMergies of the environment, and in so doing the environment is "loaded" (meaning to strain, stress, or
pressure). Figure 4 shows environmental loading as the interaction of purchased EMergy and nonrenewable

storage of EMergy from within the system with the renewable EMergy pathway, through environmental work. An
index of environmental loading, the Environmental Loading Ratio (ELR) is the ratio of nonrenewable EMergy
(N+F) to renewable EMergy (I) as follows:

ELR = (N+F)/I (2)

Low ELRs reflect relatively small environmental loading, while high ELRs suggest greater loading. The
ELR reflects the potential environmental strain or stress of a development when compared to the same ratio for the
region, and can be used to calculate carrying capacity.

Evaluating Regional and Local IRs and ELRs
Figure 5 is a simplified diagram of a regional economy and a sector of the economy. The sector uses of
renewable EMergy (I,) and purchased EMergy from both the local (Fm) and world economy (Fi). The sector is
actually a part of the regional economy, but is shown separately to highlight the comparison between it and the
region in which it is embedded. The Investment Ratio in the regional economy is derived using the ratio of
purchased EMergy (F) to resident EMergy inputs (Im + Nm) as follows:

IRm = F/ (Im + Nm) (3)

The Investment Ratio of the sector (IR,) is calculated in a similar manner, accounting for all sources of renewable
and purchased EMergy as follows:

IR, = (F. +F)/(I, + N,) (4)

The Environmental Loading Ratio for the region and sector within the regional economy are calculated
somewhat differently from each other. The regional ELR is calculated as the ratio of nonrenewable (F + Nm) to
renewable EMergy (In) as before. However, calculation of the ELR for the economic sector has to take into
account the portion of F. that comes from I,, since that area of environment is not adding to the "load" on the
environment of the sector but, in effect, is part of the environmental support for the sector. Thus the ELR for the
sector is calculated by subtracting the portion of F. that is from I,. This is done by first calculating the total
EMergy budget of the main economy (Total EMergy = Fm+Fi+Nm+N,+Im+I,), then dividing by Im to determine the
percent of the total that is derived from Im. Then the ELR for the sector is determined as follows:

ELRs = [Fi+(F.-kF.) + N, / (I,+kFm) (5)
k = percent of total EMergy budget that is from I (refer to Figure 5)

Determining Carrying Capacity for Economic Investments
Once the ELR for a region is known and the total annual nonrenewable EMergy use by a development is
determined, the area of land necessary to balance the development can be calculated using the average annual flux
of renewable EMergy per year per unit area of landscape (renewable EMpower density). Renewable EMpower
density is derived from the analysis of the regional or national economy. To determine the area of support necessary
for a proposed development and thus the carrying capacity (i.e., the area of landscape required for the
development), the ELR for the region is calculated (as above), and then the following equivalent proportion is

ELR(regon) = ELR(dv& lopmet) (6)
ELR(,rcon) = known
ELR,&vlopmet) = [Fi+(Fm-kF.) + NJ / (I,+kFm)

and the equation is solved as follows:

(I,+kF.) = [F,+(F.-kF,) + NJ / ELR(rCon) (7)

Once the quantity (I,+kF.) is known, the area of landscape required to balance the proposed development can be
calculated as follows:

Support Area = (I,+kFm)/ I(r,,n)

I(rcgo) = known regional EMpower density of renewable inputs (sej/unit area)

Criteria for Alternative Public Policies
Public policy alternatives that involve decisions regarding a development and use of resources are guided by
two criteria in this study: (1) the alternative should increase the total EMergy inflow to the economy, and (2) the
alternative should be sustainable in the long run.
Development alternatives that result in higher EMergy inputs to an economy increase its vitality and
competitive position. A principle that is useful in understanding why this is so is the Maximum EMergy Principle
(which follows from the work of Lotka [1922a], who named it the "maximum power principle"). In essence, the
Maximum EMergy Principle states that the system (or development alternative, in this case) that will prevail in
competition with others is the one that develops the most useful work with inflowing EMergy sources. Useful work
is related to using inflowing EMergy in reinforcement actions that insure and, if possible, increase the inflowing
EMergy. The principle is somewhat circular. That is, processes that are successful maximize useful work, and useful
work is that work which increases inflowing EMergy. It is important that the term "useful" is used here. Energy

dissipation without useful contribution to increasing inflowing EMergy is not reinforcing, and thus cannot compete
with systems that use inflowing EMergy in self-reinforcing ways. Thus, drilling oil wells and then burning off the oil
may use oil faster (in the short run) than refining and using it to run machines, but it will not compete in the long
run with a system that uses oil to develop and run machines that increase drilling capacity and, ultimately, the supply
of oil.
Development alternatives that do not maximize EMergy cannot compete in the long run and are "selected
against". In the trial and error processes of open markets and individual human choices, the patterns that generate
more EMergy will tend to be copied and will prevail. Recommendations for future plans and policies that are likely
to be successful are those that go in the natural direction toward maximum EMergy production.
The second guiding criterion is that development alternatives be sustainable in the long run. To be sure,
sustainability is an elusive concept. Ultimately, sustainable developments are activities that use no nonrenewable
energy, for once supplies have dwindled, developments that depend on them must also dwindle. However, the
criteria for maximum EMergy would suggest that energy be used effectively in the competitive struggle for existence.
Thus, when energy is available, its use in actions that reinforce overall performance is a prerequisite for
sustainability. To do otherwise would suggest that the development would not be competitive, and in the short run
would not be sustainable. This alternative (no use of nonrenewable energy) provides the lower bound for
sustainability. The upper bound is determined by the Maximum EMergy Principle as well. Sustainable
developments are those that operate at maximum power, neither too slow (efficient) nor too fast (inefficient). The
question of defining sustainability becomes one of defining maximum power. In this analysis, we use the Investment
Ratio and the Environmental Loading Ratio as the criteria for sustainability. By matching the ratios of a
development with those of the economy in which it is imbedded, a proposed development is neither more nor less
sustainable than the economy as a whole.

Analysis of Public Policy Options
The EMergy analysis procedure is designed to evaluate the flows of energy and materials of systems in
common units that enables one to compare environmental and economic aspects of systems. Usually questions of
development policy and uses of resources involve environmental impacts that must be weighed against economic
gains. Most often impacts and benefits are quantified in different units resulting in a paralysis of the decision-
making process because there is not a common means of evaluating the trade-offs between environment and
development. EMergy provides a common basis, the energy of one type that is required by all productive processes.
While "Ecological Economics" and the methods of EMergy Analysis are comparatively new and still
evolving, and often difficult to understand, we believe they offer an important step in developing a quantitative basis
for public policy decision making.

energy flow from outside the system.

HEAT SINK drains out degraded energy
after its use in work.

delivers energy flow.

ENERGY INTERACTION requires two or
more kinds of energy to produce high quality
energy flow.

flows in exchange for energy.

GENERAL PURPOSE BOX for any sub-unit
needed, is labeled to indicate use.

PROCEDURE UNIT converts and
__ concentrates solar energy, self-maintaining:
Details may be shown inside.

CONSUMER UNIT uses high quality energy,
self-maintaining; details may be shown inside.

Figure 2. Energy language symbols.

Purchased Inflow (F)

Inflow From Renewable or
Non Renewable Source

Outflow of
Upgraded Energy (Y)

Net Emergy Yield Ratio = (Y- F)/F

Imports (A)

Nation A: Emergy Exchange Ratio



Energy D

A+ C (all in emergy
Transformity of D = ABC of some type)
D (energy)


Figure 3. Simplified diagrams illustrating (a) the calculation of Net EMergy Yield Ratio for
economic conversion where purchased energy is used to upgrade a lower grade resource, (b) the
calculation of EMergy Exchange Ratio for trade between tow nations, and (c) the calculation of a
Transformity for the flow "D" that is a product of the process that requires the input of three
different sources of EMergy.

Purchased Inputs (F)

Investment Ratio of Regional Economy: IR=F/(I + N)
Environmental Loading Ratio of Regional Economy: ELR = (F + N)/1
Yield Ratio of Regional Economy: YR = Y/F

Figure 4. Diagram illustrating a regional economy that imports purchased inputs (F) and uses
resident renewable inputs (I) and nonrenewable storage (N). Several ratios used for comparison
between systems are given below the diagram and are explained in the text The letters on
pathways refer to flows of EMergy per unit time, thus ratios of flows are dynamic and changing
over time.

Investment Ratio for Economic Sector: IR = F+F
Environmental Loading Ratio for Economic Sector: ELR=
where K= percent of FM that is from IM

FI +(FM- KFM) -+ N
Is +KFM :

Yield Ratio for Economic Sector: YR =

Figure 5. Diagram of a regional economy showing the flows of energy from external sources and
within the economy. One sector of the economy is shown separated from the main economy in the
lower left. The sector receives flows of energy from imports (FI), from the main economy (FM),
from nonrenewable storage (Ns), and from the environment (Is). The ratios given below the
diagram are explained in the text.

SECTION 3A: EMergy Analysis of Mexico

by Agustin Gonzalez


Given in Figure A-1 is a map of the physiographic features of Mexico. The total land area of Mexico is
1,958,201 km2, which includes 5,073 km2 of insular land. Its land borders are comprised of the United States on the
north, and Guatemala and Belize to the south. The eastern coastline includes 2,070 km along the Gulf of Mexico
and 735 km along the Caribbean Sea. The western coastline encompasses 7,338 km on the Pacific Ocean and the
Sea of Cortez. Mexico's Economic Exclusive Zone extends the total sovereign land area to 2,715,012 km2 (INEGI,
1990). The area of the continental shelf is 442,100 km2, at a depth of 200 m (World Resources, 1990).
The topography of Mexico ranges from low desert plains and jungle-like coastal strips to high plateaus and
rugged mountains. Beginning at the Isthmus of Tehuantepec in southern Mexico, an extension of a South American
mountain range runs north almost to Mexico City, where it divides to form the coastal Occidental (west) and
Oriental (east) Ranges of the Sierra Madre. Between these ranges lies the great central plateau, a rugged tableland
2,400 km (1,500 mi) long, and as much as 800 km (500 mi) wide. From a low desert plain in the north, the plateau
rises to 2,400 meters (8,000 ft) above sea level near Mexico City.
Mexico's climate is generally more closely related to altitude and rainfall than to latitude. Most of Mexico
is dry; only about 12% of the total area receives adequate rainfall in all seasons, while about one-half is deficient in
moisture throughout the year. Temperatures range from tropical in the coastal lowlands to cool in the higher
elevations. Mexico is the most populous Spanish-speaking country in the world and the second most populous (81
million) country in Latin America (after Brazil). More than one-half of the people live in the central portion of the
Mexico is rich in mineral and energy resources. A leading producer of silver, sulfur, lead, and zinc, it also
produces gold, copper, manganese, coal, and iron ore. The discovery of extensive oil fields in the coastal regions
along the Gulf of Mexico in 1974 enabled the country to become self-sufficient in crude oil and to export significant
amounts of petroleum. The Mexican economy remains heavily dependent on petroleum production and exports.
Mexico ranks as the world's fifth largest oil producer, with an average production of 2.5 million barrels per day.
About half of the oil is refined and consumed domestically, leaving an average of 1.29 million barrels per day for
Mexico's manufacturing sector's main products are cement, aluminum, artificial fibers, chemicals, fertilizers,
petrochemicals, and paper. A growing automobile industry has become one of Mexico's most important industrial
and export sectors. 1989 agricultural production showed no growth, as a series of natural events and economic
realities have all limited output. Mexico's tourist attractions, from coastal resorts to archeological sites, bring
approximately 6 million tourists per year, some 90% of them U.S. citizens (USDS, 1990). One of the coastal resorts,
Puerto Vallarta, shares half of the Bahia de Banderas, where the first steps of the study of Nayarit will take place.


The plan of study consisted in evaluating the resource base of the national economy of Mexico in order to further
evaluate the resource base of the state of Nayarit, and of the Bahia and Valle de Banderas region; to evaluate the
environmental impacts on the development of the coastline of Nayarit; and, using EMergy analysis, to evaluate
tourism, sewage disposal, impacts on fisheries, and to develop a terrestrial resources management plan for Nayarit's
coastal zone.


Mexico EMergy Analysis
The overview energy circuit diagram of Mexico is shown in Figure A-2. An evaluation of the overall
resource basis of the Mexican economy in 1989 is given in Table A-1. The main components of the economy of the
country are listed, including exports and imports. In terms of renewable resources, those with higher solar EMergy
are the most important for the economy, as reflected in terms of macroeconomic value. For Mexico these are: rain
(1324 E+20 solar EMjoules [sej]), Earth cycle (1085 E+20 sej), and waves (415 E+20 sej). The most important
indigenous renewable energy resources are livestock production (3210 E+20 sej), agriculture production (1962 E+20
sej), and fisheries (508 E+20 sej). The most important nonrenewable sources within Mexico were found to be oil
(1490 E+20 sej), silver (1200 E+20 sej), thermoelectricity (626 E+20 sej) and steel/Iron (519 E+20 sej).
Exports with the highest solar EMergy values were silver (5723 E+20 sej), oil (1538 E+20 sej), copper (156
E+20 sej), zinc (115 E+20 sej) and cash crops (73 E+20 sej). Imports with the highest values were machinery (398
E+20 sej), agriculture and forestry products (254 E+20 sej), and oil-derived products (172 E+20 sej).

Summary of EMergy Indices
Tables A-2 and A-3 and Figure A-3 summarize solar EMergy flow in Mexico for 1989. The flow of
nonrenewable resources is 11364.4 E+20 sej/yr, with 67.8% of the total flow (7707.7 E+20 sej/yr) being exported
unused. The rest of the nonrenewable resource flow is mostly used in the urban and industrial sectors, with a value
of 3594 E+20 sej/yr. This accounts for 31.6% of the total EMergy flow, leaving only 63 E+20 sej/yr, or about 0.6%,
for use in rural areas.
Comparisons of socio-economic and EMergy indices are given in Table A-4. The Mexico EMergy/$ ratio of
3.32 E+12 sej/$ is higher than that of the USA, but lower than those of Papua New Guinea, Brazil, Australia, and
the World average. This corroborates earlier findings of an EMergy analysis of the State of Texas, USA (Odum et
al., 1987). The EMergy/$ ratio for Mexico is thus not high enough to classify it as an undeveloped country. In fact,
72.6% of its population is considered to be urban.




The Economy of Mexico
The economy of Mexico is driven, in part, by renewable energies like rainfall, tidal energy, and geologic
uplift. When expressed in solar EMergy, the renewable energy basis for Mexico's economy amounts to about 24%
of its total yearly flux. To avoid double counting of renewable energy, since the various renewable energies driving
an economy are derived from the same source (solar energy), only the largest from each of the separate global
energy inputs are included as driving forces. In Mexico, the renewable energies are rainfall, river inflows, and tidal
energy. Rainfall is the single most important input (about 95% of the total yearly flux). The ebb and flow of tidal
energy that continually flushes and mixes the extensive marine ecosystems increasing Mexico's fishery potential
amount to about 3% of the total renewable EMergy flux. And the energy inflow of rivers that cross the Mexico-U.S.
border account for about 2% of the renewable EMergy flux. The geologic process of earth uplift, while not included
in the accounting procedure to avoid double-counting, is none-the-less extremely important. The geologic process
that lifts and buckles the earth's crust and makes available sources of mineral wealth and the materials from which
fertile soils are made, is important to the economy, comprising about 40% of the flux of renewable EMergy if it
were included.
Nonrenewable energy sources, when expressed as solar EMergy, make up about 76% of the total yearly
EMergy flux. Of the total EMergy flux, about 68% is from sources of nonrenewable EMergy derived from within
Mexico, and about 24% is from renewable sources, giving a total of 82% that is derived from within Mexico. The
single largest nonrenewable source from within Mexico is silver, of which nearly 83% is exported. Crude oil is the
second largest nonrenewable energy flow, and about 51% is exported.
Mexico's EMergy balance of payments (imports minus exports) is negative. In other words, more EMergy
is exported annually than is imported. Expressed as a ratio (exports/imports), Mexico exports about 7.5 times the
EMergy it imports.
Comparisons of indices of Mexico's economy with other nations (Table A-4) is striking because of the
differences related to population and EMergy use. Its population density is the highest of all countries listed and its
EMergy use per unit area is second only to the U.S. Yet because of the high population density, Mexico ranks last
in per capital EMergy use. In addition to this relatively low per capital EMergy consumption, the relative buying
power of the Mexican monetary system (measured by the ratio of EMergy/$) is indicative of a more developed
economy. The net result is that, because of the low buying power, the population has much lower EMergy available
for personal consumption.



00 goo 00m

114 00'


1000 mm/yr

--16 00'

1000 mm/yr

Figure A-1. Generalized map of Mexico showing mountain regions and isobars of rainfall.



Figure A-2. Energy systems diagram of Mexico showing the interplay of renewable and
nonrenewable and purchased energy sources that drive the economy.

E20 solar emjoules/yr

-F. Q.P23

Indigenous 12750 8265.5 Exports
sourcs MEXICO"'P
R. NO.NN 11 N2


Figure A-3. Summary diagrams of the economy of Mexico in 1989. The top diagram shows the
flows of energy from renewable and nonrenewable sources and from purchased resources. The
circle of money within the central box is GDP. The bottom diagram is a further simplification of
the economy, showing the main driving energies and balance of imports and exports.

Table Al. EMergy evaluation of resource basis for Mexico, 1989.

Trans- Solar Macroeconomic
Note Item Raw Units formity EMergy Value
(sej/unit) (E20 sej) (E9 1984 US$)


Rain, chemical
Rain, geopotential
Wind, kinetic
River Geopotential
Earth Cycle




Agriculture prod
Livestock prod
Fuelwood prod
Forest extraction




15 Natural Gas 4.92E+17 J 4.80E+04
16 Oil 2.76E+18 J 5.40E+04
17 Thermoelectricity 3.13E+17 J 2.00E+05
18 Fertilizer 4.29E+12 g 5.17E+09
19 Gold 8.65E+06 g 4.40E+14
20 Silver 4.00E+08 g 3.00E+14
21 Copper 1.98E+10 g 6.80E+10
22 Zinc 1.12E+11 g 6.80E+10
23 Iron ore 5.37E+12 g 1.00E+09
24 Coal 1.22E+17 J 4.00E+04
25 Gypsum 2.87E+11 g 1.OOE+09
26 Salt 1.87E+12 g 9.20E+08
27 Minerals 6.22E+12 g 9.20E+08
28 Steel/Iron Prod. 1.97E+13 g 2.64E+09
29 Steel/Iron Cons. 1.32E+13 g 2.64E+09
30 Cement 1.83E+13 g 7.48E+08
31 Plastics 1.24E+12 g 3.80E+08
32 Top Soil 4.57E+16 J 7.37E+04


33 Oil derivatives 2.61E+17
34 Steel/Iron 1.64E+12
35 Minerals 2.53E+12
36 Agri. & Forestry 1.27E+17
37 Livestock 4.03E+14
38 Foods 3.55E+16
39 Plastics 6.37E+10
40 Chemicals 7.83E+11
41 Wood 2.55E+15
42 Paper 2.78E+16
43 Textiles 7.81E+14
44 Machinery 1.05E+10
45 Service in imports 2.34E+10
46 Tourism 1.54E+09










Table Al. Continued.

Trans- Solar Macroeconomic
Note Item Raw Units formity EMergy Value
(sej/unit) (E20 sej) (E9 1984 US$)


47 Crude Oil 2.85E+18 J 5.40E+04 1538.74 46.36
48 Oil derivatives 1.62E+17 J 6.60E+04 106.87 3.22
49 Fertilizer 2.35E+11 g 5.17E+09 12.15 0.37
50 Steel/Iron 1.38E+12 g 2.64E+09 36.51 1.10
51 Silver 1.91E+09 g 3.00E+14 5723.04 172.44
52 Copper 2.29E+11 g 6.80E+10 156.04 4.70
53 Zinc 1.69E+11 g 6.80E+10 115.02 3.47
54 Gypsum 2.60E+12 g 1.00E+09 26.04 0.78
55 Salt 5.53E+12 g 9.20E+08 50.84 1.53
56 Minerals 1.90E+12 g 9.20E+08 17.51 0.53
57 Cement 4.37E+12 g 7.48E+08 32.68 0.98
58 Agri. & Forestry 3.65E+16 J 2.00E+05 73.00 2.20
59 Fishery Products 6.51E+13 J 2.00E+06 1.30 0.04
60 Livestock 3.07E+14 J 2.00E+06 6.13 0.18
61 Foods 2.04E+16 J 8.50E+04 17.31 0.52
62 Plastics 6.40E+10 g 3.80E+08 0.24 0.01
63 Chemicals 9.41E+11 g 3.80E+08 3.58 0.11
64 Wood 1.46E+15 J 3.49E+04 0.51 0.02
65 Paper 1.60E+14 J 2.15E+05 0.34 0.01
66 Textiles 2.50E+15 J 3.80E+06 95.15 2.87
67 Machinery 5.89E+09 $ 3.32E+12 195.49 5.89
68 Service in exports 2.28E+10 $ 3.32E+12 755.53 22.76
69 Tourist Service 2.98E+09 $ 3.32E+12 98.97 2.98

Footnotes to Table Al


Cont Shelf Area = 4.42 E+11 m2 at 200 m depth (World Resources 90-91)
Land Area = 1.96 E+12 m2 (INEGI, 1989)
Insolation = 1.80 E+02 Kcal/cm2/yr (World Energy Data Sheet)
Albedo = 0.30 (%, given as decimal) estimate

Energy(J) = (area incL shelf)*(avg insolation)*(1-albedo)
=( m2)*( Cal/cm2/y)*(E+04cm2/m2)*
(1-0.30)*(4186 J/kcal)
(J) = 1.26 E+22


Land Area = 1.96 E+12 m2 (INEGI, 1989)
Cont Shlf Area = 4.42 E+11 m2 @ 200 m depth (World Resources 90-91)
Rain @ (Land) = 0.73 m/yr avg. for 1966-1987 (CNA, SARH, 1991)
Rain @ (shelf) = 0.33 m/yr (est. as 45% of tot. rain)
Etr = 0.90 m/yr (% given as decimal) (IAM, UG) (SRH, 1976)
@ E-T of 0.662782 m/yr calc. by turc method @ mean Temp (21 C)

Energy (land) = (area)*(ET)*(rainfall)*(Gibbs #)
= ( m')*( m)*(1000 kg/m3)*(4.94 E+03 J/kg)
(J) = 6.38 E+18 or 7.09 E+18 (J) using method as for USA (HTO, 1992)

Energy (shelf) = (area of shelf)*(rainfall)*(Gibbs #)
(J) = 7.21 E+17

Total energy (J) = 7.10 E+18 or 7.81 E+18 (J) using method as for USA (HTO, 1992)


Area = 1.96E+12 m2 INEGI, 1989
Rainfall = 0.73 m/yr avg. for 1966-1987 (CNA, SARH, 1991)
Avg. Elev = 1059.00 m (avg. from WATER ATLAS, SRH, 1976)
Etr = 0.90 m/yr (% given as decimal) (IAM, UG) (SRH, 1976)
@ E-T of 0.662782 m/yr calc. by turc method a mean Temp (21 C)
Runoff rate = 0.10 a(1-Etr) as a X in decimal point

Energy (J) = (area)*(% runoff)*(rainfall)*(avg elevation)*(gravity)
= ( m2)*( m)*(1000 kg/m3)*( m)*(9.8 m/s )

(J) = 1.49 E+18 or 1.49 E+19 (J) using method as for USA (HTO, 1992)


2 ground Level = 3.90 E+12 kwh/yr (World Energy Data Sheet, 1980)
@ 860.5 kcal/kwh
a 4186 J/kcal

Energy (J) = 1.40 E+19 J/yr


@ coast line = 4.45 E+11 kwh/yr (World Energy Data Sheet, 1980)
@ 860.5 kcal/kwh
a 4186 J/kcal

Energy (J) = 1.60 E+18 J/yr


Cont ShLf Area = 4.42E+11 m^2 (globe resources 90-91)
Avg Tide Range = 0.91 m (avge. from 35 stations) (IG-F, UNAM, 1990)
Density = 1.03E+03 kg/m^3 (Odum et at. 1983)
Tides/year = 7.30E+02 (estm. of 2 tides/day in 365 days)

Energy (J) = (shelf)(0.5)(tides/y)(mean tidal range)^2
(density of seawater)(gravity)
=( m^2)*(0.5)*(._ /yr)*( m)^2*( kg/m^3)

(J) = 1.34E+18 or 1.34E+17 (J) using method as for USA (HTO, 1992)


Energy (J) = (flow)(elevation change)(gravity)(sec/yr)
(water weight)(0.5 energy available to Mexico)

Energy (J) = (m3/s)(m)(9.8m/s^2)(1000kg/m^3)(3.1E7s/yr)(0.5)

River Flow (m^3/s) Elevation change (m) Energy (J)

Colorado 65.55 200.00 2.84E+15
Bravo 11.80 1123.00 2.05E+15
Suchiate 23.26 800.00 2.88E+15
Usumacinta 1751.00 350.00 ** 1.18E+17

(0.7 energy avail, to Mex.)
** (0.625 energy avail. to Mex.)

Flow data from (WATER ATLAS, SRH, 1976)
ELev change data (Mex. topographic maps, INEGI)
Total energy (J) = 1.26E+17


Land Area = 1.96E+12 m^2 (INEGI, 1989)
Heath Flow/Area = 1.91E+06 J/m^2/yr

@ 60.6 rm/m^2 avge. for N-America Continent (Jessop, 1990).
@ 1 W/m^2 = 2.388E-05 cal/cm^2 sec

Energy (J) = (Land area)(Heat flow per unit area)

(J) = 3.74E+18


Kilowatt Hrs/yr = 2.40E+10 KwH/yr @ 1989 (II I.G.,CSG,SPP, 1990)
@ 3.60E+06 J/KwH
Energy(J) =(_ KwH/yr)*( J/KwH)

(J) = 8.66E+16

Ag. Prod = 6.70E+07 MT at 1989 (II I.G.,CSG.,SPP,1990)

Energy(J) = (3.74E+07 MT)*(1E06 g/MT)*(3.5 Kcal/g)*(4186 J/Cal)

= 9.81E+17

L'stock Prod = 9.59E+06 MT at 1989 (II I.G.,CSG.,SPP, 1990)

Energy(J) = (1.13E+07 MT)*(1E+06 g/MT)*(4 Cal/g)*(4186 J/Cat)
= 1.61E+17

Fish Catch = 1.52E+06 MT at 1989 (II I.G.,CSG.,SPP, 1990)

Energy(J) = (1.28E+06 MT)*(1E+06 g/MT)*(4 Cal/g)*(4186 J/Cal)
= 2.54E+16

Fuetwood Prod = 4.43E+05 m^3 (m^3 R, 1989) (II I.G.,CSG.,SPP, 1990)

Energy (J) = (_ m^3)(E6 cm^3/m^3)(10176 J/cm^3)
(J) = 4.51E+15

Harvest = 8.45E+06 m^3 (m^3 R, 1989) (II I.G.,CSG.,SPP, 1990)

Energy(J) = (_ m3)(1E6 cm^3/m^3)(10176 J/cm^3)
= 8.59E+16


15 NATURAL GAS Consumption = (internal sales + imports)

Internal sales = 1.23E+10 m^3 @ 1989 (IMP, 1990)(II I.G.,CSG.,SPP., 1990)
@ 3.53E+01 ft^3/m^3
imported = 1.66E+10 ft^3/yr a 1989 (IMP,1990)

Energy(J) = ((( _m3)*(_ftA3/m^3))+(_ft^3))*(1031 BTU/ft^3)*(1055 J/BTU)

(J) = 4.92E+17

16 OIL Consumption = (production exports)

production = 9.17E+08 barrels/yr a 1989 (IMP, 1990)
exports = 4.66E+08 barrels/yr B 1989 (IMP, 1990)

Energy(J) =(Prod. export. in b/yr)*(5800000 BTU/barrel)*(1055 J/BTU)
= 2.76E+18

17 THERMOELECTRICITY Consumption = (production exports + imports)

production = 8.83E+04 Gwh/yr B 1989 (II I.G.,CSG, SPPP, 1990)
exports = 1.93E+03 Gwh/yr B 1989 (II I.G.,CSG, SPPP, 1990)
imports = 6.12E+02 Gwh/yr B 1989 (II I.G.,CSG, SPPP, 1990)

Energy(J) =(Consumed GwH/yr)*(1.OE+06 KwH/GwH)*(3.6E+06 J/KwH)
= 3.13E+17

18 FERTILIZER Consumption = Internal sales

Internal sales = 4.29E+06 MT/yr B1989 (II I.G.,CSG, SPP, 1990)
Energy(g) = (_ MT/yr)*(1E6 g/MT)
(g) = 4.29E+12

19 GOLD Consumption = production
Production = 8.65E+03 Kg/yr B 1989 (INEGI,1990)(The Economist,91-92)
Energy (grams) = (_Kg)*(1000 g/Kg)
(g) = 8.65E+06

20 SILVER Consumption = (Production Exports)

Production = 2.31E+03 MT/yr B 1989 (INEGI,1990)(The Economist,91-92)
Exports = 1.91E+03 MT/yr B 1989 (INEGI,1990)(II I.G.,CSG,SPP, 1990)

Energy (grams) = (Prod.-Exp. MT)*(1000000 g/MT)
(g) = 4.00E+08


Production =
Exports =

Energy (grams) =
(g) =


Production =
Exports =

Energy (grams)=
(g) =


Production =
Exports =

Energy (grams) =
(g) =


Production =
Energy (Joules) =
(J) =


Production =
Exports =

Energy (grams) =
(g) =


Production =
Exports =

Energy (grams) =
(g) =


Production =
Exports =

Consumption = (Production Exports)

2.49E+05 MT/yr a 1989 (INEGI,1990)(The Economist,91-92)
2.29E+05 MT/yr a 1989 (INEGI,1990)(Mexico Data Bank, 1990)

(Prod Exp MT)*(1000000 g/MT)

Consumption = (Production Exports)

2.81E+05 MT/yr a 1989 (INEGI,1990)(The Economist,91-92)
1.69E+05 MT/yr a 1989 (INEGI,1990)(Mexico Data Bank, 1990)

(Prod Exp_MT)*(1000000 g/MT)

Consumption = (Production Exports)

5.37E+06 MT/yr @ 1989 (INEGI,1990)(The Economist,91-92)
O.OOE+00 MT/yr a 1989 (INEGI,1990)(Mexico Data Bank, 1990)

(Prod Exp_MT)*(1000000 g/MT)

Consumption = production

4.24E+06 MT/yr a 1989 (INEGI,1990)(The Economist,91-92)
(_MT)*(0.9072 sht. Ton/MT)*(3.18E10 J/sht. Ton)

Consumption = (Production Exports)

2.89E+06 MT/yr a 1989 (INEGI,1990)(The Economist,91-92)
2.60E+06 MT/yr 2 1989 (INEGI,1990)

(Prod Exp MT)*(1000000 g/MT)

Consumption = (production Exports)

6.97E+06 MT/yr a 1988 (Mexico Data Bank, 1990)
5.10E+06 MT/yr a 1988 (BANCOMEX,1990)

(Prod Exp_MT)*(1000000 g/MT)

(Pb,non-ferrous metals,Coke, Mn,non-metalic)
Consumption = (production exports)
8.12E+06 MT/yr 2 1989 (INEGI, 1990)

Energy(g) =(Prod Exp_MT)*(1000000 g/MT)
(g) = 6.22E+12

28 STEEL & IRON (Steel, Pig & Sponge iron, Rolled products)

Steel = 7.92E+06 MT/yr a 1989 (Mexico Data Bank, 1990)
Pig iron = 3.25E+06 MT/yr a 1989 (Mexico Data Bank, 1990)
Sponge iron = 2.23E+06 MT/yr a 1989 (Mexico Data Bank, 1990)
Rolled products. = 6.30E+06 MT/yr a 1989 (Mexico Data Bank, 1990)

Total Productn. = 1.97E+07 MT/yr a 1989 (Mexico Data Bank, 1990)
Energy (g) = ( MT/yr)(1000000 g/MT)
(g) = 1.97E+13

29 STEEL & IRON Consumption

consumption = 1.32E+07 MT/yr a 1989 (II I.G., CSG, SPP, 1990)
Energy (g) = (_MT/yr)(1000000 g/MT)
(g) = 1.32E+13

Consumption = (production Exports)

Energy (grams)


Energy (g)

= 2.25E+07 MT @ 1988 (Mexico Data Bank, 1990)
= 4.20E+06 MT @ 1988 (Mexico Data Bank, 1990)
= (Prod Exp_MT)*(1000000 g/MT)
= 1.83E+13


= 1.24E+06 MT/yr 2 1989 (PLastics yearbook,IMPI, 1990)
= (_MT/yr)(1000000 g/MT)
= 1.24E+12


Land Area = 1.96E+12 m^2 (INEGI, 1990)
Arable land = 2.55E+11 m^2 @ 1986 as 13 % of Land area (FAO,1989)
Forest land = 4.50E+11 m^2 B 1986 as 23 % of Land area (FAO,1989)
soil loss arbl land = 8.50E+02 g/m^2/yr (estimated from Odum et at 1983)
new soil form. = 1.26E+03 g/m^2/yr (assume for half of forest area)
soil loss = ((Forest_mA2)*(0.5))*(new soil form. g/m^2/yr)
= 2.84E+14 g/yr
soil eroded = (Arable m^2)*(soil Loss Arabt. Land_g/m^2/yr)
= 2.16E+14 g/yr

(soil loss)-(soil eroded) =
= 6.74E+13 g/yr

Energy (J) = ( g/y)(0.03 organic)(5.4 Kcat/g)(4186 J/Kcal)
(J) = 4.57E+16



Energy (J)


Energy (g)


Energy (g)

= 4.35E+07 bts/yr @ 1989 (BANCOMEX,1990)
= (_bls/yr)(5.7E6 BTU/bls)(1055 J/BTU)
= 2.61E+17 value US ($)= 8.13E+08

= 1.64E+06 MT/yr @ 1989
= (_ MT/yr)*(1E6 g/MT)
= 1.64E+12 value US

(metal, non-metal)

= 2.53E+06 MT/yr @ 1989
= (_ MT/yr)*(1E+6 g/MT)
= 2.53E+12 value US

(BANCOMEX, 1990)

($)= 1.31E+09

(BANCOMEX, 1990)

($)= 3.88E+08


Energy (J)

Energy (J)

= 8.68E+06 MT/yr B 1989 (BANCOMEX, 1990)
= ( MT/yr)*(1E6g/MT)*(3.5 Kcal/g)*(4186 J/Kcal)
= 1.27E+17 value US ($)= 1.75E+09

= 1.09E+05 MT/yr @ 1989 (II I.G.,CSG,SPP,1990)(BANCOMEX, 1990)
= (1E5 MT/yr)*(1E6 g/MT)*(4 Kcal/g)*(4186 J/Kcal)*(.22 protein)
= 4.03E+14 value US ($)= 2.48E+08


Energy (J)

= 2.35E+06 MT/yr & 1989 (BANCOMEX, 1990)
= MT)*(1E6g/MT)*(15.1E3 J/g)
= 3.55E+16 value US ($)= 2.01E+09




Imports = 6.37E+04 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (g) = (_ MT/yr)*(1000000 g/MT)
(g) = 6.37E+10 value US (S)= 2.59E+08


Imports = 7.83E+05 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (g) = (7.8 E5 MT/ yr)*(1E6g/MT)
(g) = 7.83E+11 value US ($)= 2.46E+09


Imports = 1.45E+05 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT/yr)*(1E6 g/MT)*(1.72733 cm^3/g)*(10176 J/cm^3)
(J) = 2.55E+15 value US ($)= 1.11E+08


Imports = 1.58E+06 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT/yr)*(1E6 g/MT)*(1.72733 cm^3/g)*(10176 J/cm^3)
(J) = 2.78E+16 value US ($)= 9.34E+08


Imports = 5.21E+04 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT/yr)*(1E6 g/MT)*(15E3 J/g)
(J) = 7.81E+14 value US ($)= 7.00E+08

44 MACHINERY (transportation & industry)

Imports = 1.05E+10 US (S) @ 1989 (BANCOMEX, 1990)

Value US (S) = 1.05E+10


Dollar value = 2.34E+10 $US @1988 (BANCOMEX, 1991)

US ($) = 2.34E+10


Dollar Value = 1.54E+09 $US @ 1989 (II I.G.,CSG, SPP, 1990)

US ($) = 1.54E+09



Exports = 4.67E+08 Barrels/yr @ 1989 (BANCOMEX, 1990)
Energy (J) = (4.67E8 B/yr)*(6.1E9 J/Barrel)
(J) = 2.85E+18 value US($) = 7.29E+09


Exports = 2.70E+07 bls/yr @ 1989 (BANCOMEX,1990)
Energy (J) = (_bls/yr)(5.7E6 BTU/bls)(1055 J/BTU)
(J) = 1.62E+17 value US ($)= 4.24E+08


Exports = 2.35E+05 MT @ 1989 (II IGCSG,SPP,1990)
Energy (g) = (2.35E5 MT)*(1E6 g/MT)
(g) = 2.35E+11 value US(S) = 2.98E+07


Energy (g)


Energy (grams)



Energy (g)

Energy (g)

= 1.38E+06 MT/yr 0 1989 (BANCOMEX, 1990)
= (1.6E6 MT/yr)*(1E6 g/MT)
= 1.38E+12 value US($) = 8.67E+08

= 1.91E+03 MT/yr @ 1989 (INEGI,1990)(II I.G.,CSG,SPP, 1990)
= ( MT)*(1000000 g/MT)
= 1.91E+09 value US($) = 3.47E+08

= 2.29E+05 MT/yr @ 1989 (INEGI,1990)(Mexico Data Bank, 1990)
= (_MT)*(1000000 g/MT)
= 2.29E+11 value US($) = 1.48E+08

= 1.69E+05 MT/yr 0 1989 (INEGI,1990)(Mexico Data Bank, 1990)
= (_MT)*(1000000 g/MT)
= 1.69E+11 value US($) = 7.91E+07


Energy (grams)


Energy (g)


Energy (g)

= 2.60E+06 MT/yr @ 1989 (INEGI,1990)
= (_MT)*(1000000 g/MT)
= 2.60E+12 value US($) = 3.70E+07

= 5.53E+06 MT/yr 0 1988 (BANCOMEX,1990)
= (_MT)*(1000000 g/MT)
= 5.53E+12 value US($) = 6.59E+07

(metal, non-metal)

= 1.90E+06 MT 0 1989 (BANCOMEX, 1990)
= (_ MT)*(1E6 g/MT)
= 1.90E+12 value US(S) = 2.75E+08


Exports =
Energy (g) =
(g) =


Fresh Fruit

4.37E+06 MT 0 1988 (Mexico Data Bank,
(_MT)*(1000000 g/MT)
4.37E+12 value US(S) = 1.56E+08

(cash crops)

01989 (BANCOMEX, 1990)
2.45E+05 MT
4.39E+05 MT
8.62E+05 MT
4.07E+05 MT
3.06E+05 MT
8.93E+04 MT
1.43E+05 MT
2.49E+06 MT


Energy (J) = (_ MT)*(1E+06 g/MT)*(3.5 Cal/g)*(4186 J/Cal)
(J) = 3.65E+16 value US(S) = 1.46E+09


Exports =
Energy (J) =
(J) =

1.77E+04 MT 0 1989 (BANCOMEX, 1990)
(1.77E4 MT)(1E+06 g/MT)(4 Cal/g)(4187 J/Cal)(.22 prot)
6.51E+13 value US($) = 4.70E+07


Exports = 8.33E+04 MT @ 1989 (II Inf. de Gob. 1990, SPP)(SARH,1991)(BANCOMEX,1990)
Energy (J) = (8.33E4 MT/yr)(1E6 g/MT)(4 Kcal/g)(4186 J/CaL)(.22 protein)
(J) = 3.07E+14 value US($) = 2.46E+08


Exports = 1.35E+06 MT/yr a 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT)*(1E6g/MT)*(15.1E3 J/g)
(J) = 2.04E+16 value US(S) = 1.27E+09


Exports = 6.40E+04 MT/yr a 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT/yr)*(1000000 g/MT)
(J) = 6.40E+10 value US(S) = 1.59E+08


Exports = 9.41E+05 MT @ 1989 (BANCOMEX, 1990)
Energy (g) = (_ MT)*(1E6 g/MT)
(g) = 9.41E+11 value US($) = 1.51E+09


Exports = 8.31E+04 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT/yr)*(1E6 g/MT)*(1.72733 cm^3/g)*(10176 J/cm^3)
(J) = 1.46E+15 value US($) = 1.97E+08


Exports = 9.12E+03 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT/yr)*(1E6 g/MT)*(1.72733 cm^3/g)*(10176 J/cm^3)
(J) = 1.60E+14 value US($) = 2.69E+08


Exports = 1.67E+05 MT/yr @ 1989 (BANCOMEX, 1990)
Energy (J) = (_ MT/yr)*(1E6 g/MT)*(15E3 J/g)
(J) = 2.50E+15 value US($) = 5.06E+08

67 MACHINERY (transportation & Industry)

Exports = 5.89E+09 US ($) S 1989 (BANCOMEX, 1990)

Value US ($) = 5.89E+09


Dollar Value = 2.28E+10 SUS a 1989 (BANCOMEX, 1991)

US ($) = 2.28E+10


Dollar Value = 2.98E+09 $US a 1989 (II I.G.,CSG, SPP,1990)

US ($) = 2.98E+09

Summary of flows in Mexico, 1989

Variable Item EMergy Dollars
(E+20 Sej/yr) (E+9 $/yr)

R Renewable sources (rain,tide,river) 1385.89

N Nonrenewable source flows within Mexico 11364.37

No Dispersed rural source 62.84

NI Concentrated use 3593.88

N2 Exported without use 7707.66 10.00

F Imported fuels and minerals 238.80 2.51

G Imported goods 784.33 18.95

I Dollars paid for imports 23.41

P2I Emergy value of goods and service imports 889.57

13 Dollars paid for imports minus dollars in F+G 1.95

P23I Imported services 74.14

E Dollars received for exports 22.76

PE EMergy value of goods and service exports 755.53

B Exported products transformed within Mexico 500.84 11.28

E, Dollars received for exports, minus $ in (B+N2) 1.49

PIE3 Exported services 49.46

x Gross National Product 185.00

P2 World EMergy/$ ratio, used in imports 3.80 E+12 Sej/$

P, Mexico EMergy/$ ratio 3.32 E+12 Sej/$

Table A2.

Table A3. Indices using EMergy for overview of Mexico, 1989.

Item Name of Index

1 Renewable EMergy flow

2 Flow from indigenous
non-renewable reserves

3 Flow of imported EMergy

4 Total EMergy inflows

5 Total EMergy used, U

6 Total exported EMergy

7 Fraction of EMergy used
derived from home sources

8 Imports minus exports

9 Ratio of export to imports

10 Fraction used, locally

11 Fraction of use purchased

12 Fraction used, imported service

13 Fraction of use that is free

14 Ratio of concentrated to rural

15 Use per unit area (1.96 E+12 m2)

16 Use per person (81.14 E+6 people)

17 Renewable carrying capacity
at present living standard

18 Developed carrying capacity
at same living standard

19 Ratio of use to GNP,
EMergy/dollar ratio

20 Ratio of electricity to use
(Elec: 494.94 E+20 Sej/yr)

21 Fuel use per person
(Fuel: 1553 E+20 Sej/yr)















U/area (in sej/m2)




PI=U/GNP (in sej/$)


1.39 E+23












-7.16 E+23







3.13 E+11

7.57 E+15

1.83 E+07

1.47 E+08

3.32 E+12




2.13 E+15

Table A4. Summary of EMergy indices of Mexico compared with other countries and the world.


Index Mexico U.S.A. Papua New Brazil Australia New WORLD
Guinea Zealand

EMergy use
(E+20 sej/yr) 6140 66400 1205 17820 8850 791 188000

(E+9 $/yr) 185 2600 2.3 214 139 26 5000

(E+12 sej/$) 3.32 2.6 51.79 8.4 6.4 3.0 3.8

(E+6 people) 81.14 227 3.2 121 15 3.1 5044

EMergy use/person
(E+15 sej/per/yr) 7.57 29 37.7 15 59 26 1.6

Environmental compo-
nent of EMergy
(E+20 sej/yr) 1386 8240 997 10200 4590 438 80000

Economic component
of EMergy
(E+20 sej/yr) 4754 58160 208 7600 3960 353 188000

Economic/Environment 3.43 7.1 0.21 0.74 1.1 0.8 2.35

Area (E+10 m2) 196 940 46.2 918 768 26.9 -

Population density
(people/km2) 41.4 24.2 6.9 13.2 1.9 11.5

EMergy use/area
(E+11 sej/m2/yr) 3.13 7.0 2.61 2.8 1.42 2.49

SECTION 3B: EMergy Analysis of Nayarit

by Javier Venegas


The physiographic characteristics of Nayarit are described in Volume I, Part 1 of this report. Those of
Mexico as a whole are given in Section 3A of this volume. A brief description of the physical, population and
economic characteristics of Nayarit is given below.

The State

The State of Nayarit is located midway along Mexico's Pacific coastline (see Figure B-l). It is oriented
northwest to southeast, approximately 277 km long and averaging 180 km in width. The shoreline is approximately
295 km. The eastern boundary is delimited by the western (Occidental) ridge of the Sierra Madre mountain range,
which rises to approximately 2,740 m.
Approximately two-thirds of Nayarit is comprised of rugged mountains: the Sierra Madre del Sur to the
extreme south; the Sierra Madre Occidental comprising about one-half of the state along the eastern boundary; and,
in the south central region, the westernmost portion of the neovolcanic range that transects Mexico from east to
west. The remaining third of the state (northwest) is a coastal valley expansion, approximately 100 km long by 50
km wide (INEGI, 1986).

The Population

The estimated population of Nayarit for 1990 was 870,000. Its overall density was around 31.2/km2, with
the highest concentrations (50.1 or more/km2) located in the state's mid coastal regions, surrounding the city of
Santiago Ixcuintla and extending inland to the area surrounding Tepic, the State capitol. The lowest density regions
are located in the mountainous areas of the eastern half and southernmost parts of the state. Thus, approximately
one fourth of the area is considered high density, one fourth medium, and the remaining half low density. The
growth rate, which has been declining in recent years, is calculated to be between 1.0% and 1.2%.
Approximately 67% of the population is concentrated in six of its urban centers, with Tepic being the most
populous and making up around 24.4% (212,280 inhabitants) of the total. The birth and death rates are projected
to continue at 22 and 5 per thousand, respectively. A net negative migration (-0.22%) has been reported (INEGI,
1990; SSA, 1991).


The Economy

The latest figures available on Nayarit's Gross Domestic Production (GDP) of goods and services (1980)
represented about 0.8% of the nation's total. Of this, 26.1% came from primary production (agriculture, livestock,
hunting and fishing, silviculture and mining), 24.4% from secondary production (transformation industry, electricity
and construction) and 49.6% from tertiary production (commerce and services). Of these three, the primary sector
continues to be the predominant one, even though it ranks second in the state's GDP. Agriculture, which makes up
about 76% of the primary production and 18.4% of the state's total, is the most important. Livestock is 18.1%,
fisheries about 3.3%, silviculture 2.5%, and the remainder 0.1% is taken up by mining. The top three have products
which are exported to other parts of the country as well as abroad. (INEGI, 1990; SSA, 1991).


Table B-1 provides a summary of Nayarit's 1985 economic resource base, which may be compared to that of
Mexico (Table A-i). Renewable and nonrenewable resources, as well as imports and exports are given. For the
renewable resources, riverine inputs, waves and wind, respectively, had the highest EMergy contributions. For the
indigenous renewable inputs, livestock production followed by agriculture and then fisheries were the most
significant. Electricity, followed by topsoil, was the highest in terms of nonrenewable sources.
For imports of EMergy sources, services (item 29) were first, followed by oil and then tourism. However,
because of the transient nature of tourism, some clarification needs to be made. It is an outside source of EMergy
input, but only temporarily. As such, this item is not counted in the summation under this section. For exports of
EMergy, services in exports (i.e., money received in exchange for a product or service), tourist services, and livestock
were the highest. It is important to recall that, in EMergy terms, the products which yield the highest raw units will
not necessarily produce the highest EMergy yields nor result in the highest macroeconomic value. This will
ultimately depend on the transformity value of each item. In Nayarit it was observed that those sources with the
highest EMergy value provided the highest macroeconomic contribution. The results for Nayarit seem to closely
parallel those of the whole country.
Figure B-2 is a schematic representation of Nayarit's main energy sources, flows (input and output), and
storage (see also Table B-2). It is organized in hierarchical fashion from left to right, according to the EMergy
quality (or transformity) of each item. This means that those to the left have a lower EMergy content per unit, are
more abundant and diffused, and took less effort or work to produce. Moving to the right on the diagram, things
become more concentrated, the quality per unit of each item is increased, the quantity decreased, and more
resources and energy are required for their production. It is at this high EMergy level that the development of the
interface between the economy and the ecosystems the economy draws from occurs.
The diagram in Figure B-2 shows how the main production forces driving Nayarit's economy are derived
from its coastal ecosystems (mangroves, lagoons, marshes and estuaries), forests, and agriculture. Deep heat and


uplift is probably an important contributor as well, but no reliable data regarding this has been found. Tourism is
included on the lower right hand side of the diagram. The storage symbol for "Image", located above the tourist
box, is closely associated with tourism and is a very powerful tool. The image of a resort and its natural
surroundings is advertised in commercials and other promotional activities, and is actually the driving force behind
the tourist industry.
Other aspects which might also be included in image are such things as culture. Such is the case for
Nayarit. The indigenous Huichole and Cora tribes of the Sierra Madre Occidental have maintained much of their
cultural traditions and, as such, have been an attractive force for tourism as well. If the tourists' experiences were
overall positive as to their expectations of what the image had portrayed, this positive image will be taken home and
shared with others. This acts as a feedback mechanism, reinforcing the tourist industry. This is why the line
showing the flow of tourists has no arrows--meaning that the flow is bidirectional, and is reinforced by the image
through the interaction symbol (shown flowing in both directions).
Image controls a switch (box with concave edges), which is turned on if the image is positive or off when its
negative. When it is positive, usually more foreign investment money flows in to build more assets. While this
growth is in progress, the local economy benefits because of the jobs it creates. Unfortunately, once the resort has
been built, there is not much else left to do, so workers are laid off. In addition, because the investors are
foreigners, the profits made thereafter are exported and the local economy is unable to benefit from it.
On the left in Figure B-3a are the total renewable inflows, the non-renewable EMergy used within the
state, and the non-renewable EMergy exported to other areas and markets. At the top are the high EMergy imports
which include the fuels and minerals, and goods and services. The dashed lines represent money flows in dollars per
The results of this diagram demonstrate that the highest percentage (71.5%) of imported high-quality
EMergy came from fuels and minerals (F), followed by goods (G) with 26%, and a minimum of 2.4% from services

(P213). From the environmental sources, renewable resources (R) had the highest input of 98.7% while non-
renewables (N) accounted for 1.3%. In terms of EMergy exports, exported services (P1E3) made up 98.8%, while
transformed products (B) comprised the remaining 1.2%.
Figure B-3b portrays the simplest way of illustrating the relationships in question. It is called a three-arm
diagram, and includes the sum of the environmental inputs (from the left), the sum of the purchased imports (from
the top), and the sum of the exports (to the right). Annual solar EMergy flows (EMpower) are written on each
pathway. The total annual EMergy use (sum of the inputs from indigenous plus import sources) for Nayarit was
about 5.5 E+21 sej/yr. Approximately 70.7% (3.9 E+21 sej/yr) of this is derived from imports, and 29.3% (1.6 E+21
sej/yr) from the regional renewable and non-renewable sources (environmental sources). Of this total EMergy used
and transformed within the economy, approximately 2.3% is exported abroad and to other parts of the country.


EMergy Indices

Net EMergy Yield Ratio (NEYR)
This is the ratio of the EMergy yield (5.6 E+21 sej/yr) divided by the EMergy imported (or feedback
EMergy of 3.9 E+21 sej/yr) used for processing (items 6 and 3, respectively, in Table B-3). The higher the yield
ratio of an economy's primary energy source, the more will be available for other uses besides processing its energy.
A good policy would therefore be one that utilizes those sources with the highest NEYR, even if they have to be
purchased abroad (Odum, 1992). So the higher this ratio is compared to other external competing systems, the
more of a competitive advantage it will have. For Nayarit, this ratio resulted in 1.45.

EMergy-to-Dollar Ratio (EMergy/$)
Nayarit's EMergy/$ ratio of 7.4 E+12 sej/US$ was derived by dividing the total EMergy used (5.5 E+21
sej/yr) by the Gross Domestic Product ($73.6 E+7 US$) for 1985 (Table B-3, item 19). The total EMergy used
within a system is a measure of its wealth or EMergy contribution in goods and services. The (EMergy/$ ratio)
represents the amount of real wealth which the circulating money can buy. Thus, it is a measure of the buying
power of that currency.
According to Odum (1992), a low EMergy/$ ratio suggests a high position in the economic hierarchy. The
EMergy/$ ratio is thus inversely related to economic development. As a country increases its EMergy imports and
resource utilization, EMergy production increases but money circulation does so even faster, while the resources
become limiting. As a result, the EMergy/$ ratio will continue to decrease with time, as long as these conditions
persist. Since the same money is circulating faster and less real wealth becomes available, the purchasing power of
money decreases (inflation).
Rural countries tend to have higher EMergy/$ ratios because more of the wealth goes directly from the
environment to the consumer without money being paid. People living in rural areas have less need for money
because they can obtain more of their living necessities directly from nature. This seems to be the case with Nayarit
since 67% of its population is concentrated in only 6 urban centers while the remainder is dispersed throughout the
rural regions of the state.

EMergy Per Capita Ratio
This ratio can be used as a measure of standard of living. A high value signifies a high standard. This
index provides a more realistic view of the living conditions than the income index, because it includes the unpaid
direct wealth to people from the environment. For Nayarit, the 1985 EMergy per capital ratio was found to be 6.8
E+15 sej/yr (Table B-3, item 16), which was low compared to several other nations previously studied, but higher
than the world average of 4.0 E+15 sej/yr (Odum 1992).


EMpower Density (total EMergy used/area)
This index reflects the solar EMergy being used per unit area. It is useful for measuring both the intensity
of economic development of a system plus its spatial location within the hierarchy of the economic organizations of
the region. This hierarchy has a range which goes from the lower ratios of rural areas, to the higher ones of the
cities. For Nayarit, this index was determined to be 1.95 E+14 sej/m2, which was 1 to 2 orders of magnitude higher
than that of urban nations (Odum, 1992).

EMergy Import to EMergy Export Ratio (Emergy received/EMergy Exported)
A high ratio suggests a rich economy based on external resources which come from the outside, such as
from other countries. Since much more EMergy is embedded in raw materials than in money, the disadvantage in
their exchange goes to the seller. The buying power of the money received in its sale is usually many times less than
the EMergy contribution to the economy of that raw material sold. Therefore, a good policy for any nation or state
is to limit the export of their raw materials except where a reasonable balance of EMergy is directly or indirectly
obtained in return. The idea is to make them more available to the local economy, keeping their prices to a
minimum. This creates an incentive for their use towards the manufacturing of finished products locally. Jobs are
created, and the economy at home is stimulated, rather than that of the urban and industrial nations elsewhere. So
the more exports of EMergy in finished products, the lower the ratio and thus the better off the local economy will
be. Nayarit's Import/Export ratio was found to be 0.69 (Table 3B-3, item 3/item 6).

Other useful EMergy Ratios
Table B-3 provides some other indices valuable in analyzing potentials for economic development in
relation to available resources (Odum 1992). These "investment ratios", as they are called, help identify which
activities may be feasible for the local economy; especially if safeguarding the environment and the survival of the
indigenous population's cultures are to be a priority.

The Purchased-to-Free Index (Purchased/Free = (M+S)/(R+N) = 38.66/15.94 = 2.43). This index is useful in
determining how much investment (purchased EMergy) is appropriate for a given amount of free environmental
resources, in order to be economically viable. Those systems which have sources that yield lower ratios than their
competitors will be able to sell their products at lower prices because they rely on less purchased EMergy. A good
ratio is one in which the purchased inputs do not go beyond what the environmental ones are providing. But at the
same time, in order to be competitive, it will have to at least match the surrounding regions' ratio value.
Ideally, the EMergy that the environmental flows are supplying should be the limiting factor for the
production processes. In this way, sustainable yields may be achieved. Odum (1992) states that interactions
maximize their production when they act with equal output per unit input (equal marginal utility). A design that
maximizes a unit's output delivers its effort as well and thus they all become equally limiting. This may occur when
the total available EMergy is divided equally amongst all the interactions (inputs, outputs, and feedbacks).


For Nayarit, there are apparently more purchased inputs coming in than the environment is able to provide.
It therefore needs to either seek out other environmental resources so that the load on the ones being used can be
diluted, while at the same time free inputs are increased. The other alternative is to decrease the purchased inputs.
However, in order to be economically competitive, Nayarit needs to match its ratio (2.43) to those of Mexico and its
neighboring economies such as the United States. At this time, Mexico's ratio is 0.09 while the U.S.'s is 0.04.

The Non-renewable-to-Renewable Index (Non-renewable/Renewable = (N+M)/R = 37.93/15.74 = 2.41). This index
gives an idea of how sustainable an economic system will be with regards to its resources, providing the resources are
derived from within its boundaries or economy. The higher the ratio, the less sustainable is the economy. Nayarit's
index of 2.41 signifies that it is using up non-renewable goods and resources (M+N) at a rate of 2.4 times that of the
renewable ones (R). As population and industry grow, the need for more resources will increase, especially those
for non-renewables. This will cause an increase in the index, and the carrying capacity (or sustainability) for
economies will decrease as the non-renewable resources are used up. Since Nayarit imports practically all of its non-
renewable resources (M), at this time it does not have to worry about this. But since access to non-renewable
resources (oil, minerals, etc.) are diminishing globally, this figure demonstrates that it would be prudent to limit the
use and/or reliance on them. The index will also help to set future policies if exploitation and utilization of its own
non-renewable resources are being considered.

Developed-to-Environmental Ratio [or Environmental Loading Ratio] (Developed/Environmental [ELR] =
(N+M+S)/R = 38.86/15.74 = 2.47). This index helps evaluate the impact that development has or will have on the
environment. It is similar to the Non-renewable-to-Renewable Ratio except that the added impact that the imported
services (S) will have is factored in. This is important for Nayarit's coastal zone, especially since development of a
tourist industry is occurring.
The resultant ELR was only a 0.06 point increase compared to the Non-renewable-to-Renewable Ratio.
This slight increase reflects the change caused by electricity, which was the only import of services that was added.
So in terms of preventing overloading or exceeding the carrying capacity of the environment, similar policies like
those of the previous index should be established. It should be kept in mind, however, that future increases in
imports of services will cause the ELR to rise. Since this will have a negative effect on sustainability, precautionary
measures should be taken to minimize this factor.







Coastal Zone:

I Land

t [Ocean

Figure B-1. Location map of the State of Nayarit Mexico showing the coastal zone and major

Figure B-2. Energy systems diagram of Nayarit showing the interplay of renewable and
nonrenewable and purchased energy sources that drive the economy.

E18 solar emjoules/yr

8,aE2j Imports
3- F,GP213

Indigenous 1.80E21 NAYARIT 5.6E21 Exports
R.NO.N1N2 N2B.P1 E


Figure B-3. Summary diagrams of the economy of Nayarit in 1989. The top diagram shows the
flows of energy from renewable and nonrenewable sources and from purchased resources that
drive the economy. The circle of money within the central box is GDP. The bottom diagram is a
further simplification of the economy, showing the main driving energies and balance of imports
and exports.


Table B-1. EMergy evaluation of resource basis for Nayarit, 1985.




1 Sunlight
2 Rain, chemical
3 Rain, geopotential
4 Wind, kinetic
5 Waves
6 Tide
7 River geopotential

Raw Units
(J, g, $)



Agriculture prod
Livestock prod
Fuelwood prod
Forest extraction









Oil deriv. Prods.
Natural gas
Agr.& Forst. Prod.
Plastics & Rubber
Mach.& Trans Eqp.
Service in imports


Cash Crops
Fishery Products
Service in exports
Tourist service
















(E16 sej)






(E3 1984 US$)











Footnotes to Table B-1


Cont Shlf Area = 1.06 E+07 m', @ 200 m depth (F.P., INEGI, 1985)
Land Area = 2.79 E+07 m2 (INEGI-I, 1985)
Insolation = 1.55 E+02 kcal/cm2/yr (IAM, U de G, circa 1988)
Albedo = 3.00 E-01 (% given as decimal)
Energy (J) = (area incl shelf)*(avg insolation)*(l-albedo)
= (3.85 E+07 m2)(1.5 E+02 kcal/cm2/y)(E+04cm2/m2)
(1-0.30)(4186 J/kcal)
= 1.75 E+17 J/yr


Land Area =
Cont Shlf Area =
Rain (land) =
Rain (shelf) =
Evapotrans rate=
Energy (land) (J)

Energy (shlf) (J)

Total energy (J)

2.79 E+07 m2 (INEGI-I, 1985)
1.06 E+07 m2 @ 200 m depth (F.P., INEGI, 1985)
9.44 E-01 m/yr (IAM, U de G, circa 1988)
4.20 E-01 m/yr (est. as 45% of tot. rain)
7.50 E-01 m/yr (est. as 80% of rain)
= (area)(Evapotrans)(rain density)(Gibbs no.)
= (2.79 E+07 m2)*(7.50 E-01 m/yr)*(1000 kg/m3)
*(4.94 E+03 J/kg)
= 1.03 E+14 J/yr
= (area of shelf)*(Rainfall)*(Gibbs no.)
= 2.20 E+13 J/yr
= 1.25 E+14 J/yr


Area = 2.79 E+07 m2 INEGI, 1989
Rainfall = 9.40 E-01 m IAM, UdeG, circa 1988
Avg Elev = 7.00 E+02 m (estimate)
Runoff rate = 0.25 (1.0 ET) (estimate)
Energy (J) = (area)*(% runoff)*(rain density)*(avg elevation)*(gravity)
= (2.79 E+07 m2)*(0.25)*(1000 kg/m3)*(7.0 E+02 m)*(9.8 m/s2)
= 4.78 E+13 J/yr


Energy (J) = 2.00 E+15 J/yr (est. as 1.43% of Mex's total)


(straight shoreline of 295 km, average wave height of 1 m,
and average shoaling depth of 2 m):

Ew = (0.125 pgh2)*C*(2.38 E+11) [where C = (gd)05] = 1.48 E+8 m/yr
Ew = (0.125)*(1.025 g/cm2)*(980 cm/s')*(100 cm)2(1002 cm2/m2)
*(2.38 E-11 cal/erg) = 0.298 cal/m2
(0.298 cal/m2)*(1.48 E+8 m/yr)*(295 E+3 m)(4186 J/Cal) =
Wave Energy (J) = 5.15 E+16 J/yr


Cont Shlf Area = 1.06 E+07 m2 (F.P.,Abst.Inf,INEGI,1985)
Avg Tide Range = 1.00 E+00 m (estimate, N.D.A.)
Density = 1.03 E+03 kg/m3 (Odum et al., 1983)
Tides/year = 7.30 E+02 (estm. of 2 tides/day in 365 days)
Energy(J) = (shelf)*(0.5)*(tides/y)*(mean tidal range)2
*(density of seawater)*(gravity)
=(___m2)*(0.5)*( /yr)*( ___m)2*( __ kg/m3)
= 3.89 E+13 J/yr


Flow = 5.25 E+02 m3/s (avg. flow/sec from all rivers; SPP, 1981)
Elevation Change = 4.64 E+02 m (INEGI Topo Maps, circa 1985)
Energy (J) = (flow)*(elev. change)*(grav.)*(water wt.)*(sec/yr)
= (5.25 E+02 m3/s)*(4.64 E+02 m)*(9.8m/s2)
*(1000 kg/m3)*(3.1 E+07 s/yr)
= 7.40 E+16 J/yr



Int. Combust.

= 6.94
= 6.14
= 7.55
= 7.55
= 2.72



(INEGI-II, 1985)
(INEGI-II, 1985)
(total produced in the state)
* 3.6 E+06 J/KwH


Ag. Prod = 2.70 E+06 MT in 1985 (INEGI, 1990)
Energy(J) = (2.7 E+06 MT)*(20% dry wt.)*(l E+06 g/MT)*(3.5 kcal/g)
*(4.18 E+03 J/kcal)
= 7.90 E+15 J/yr


Livestock Prod. = 1.15 E+05 MT in 1989 (Plan Nayarit, 1990)
Energy(J) = (1.15 E+05 MT)*(20% dry wt.)*(1 E+06 g/MT)
*(4 cal/g)*(4186 J/Cal)
= 3.85 E+14 J/yr


Fish Catch = 1.63 E+04 MT for 1988 (F.P., Extr Inf, INEGI, 1989)
Energy (J) = (1.63 E+04 MT)*(20% dry wt.)*(l E+06 g/MT)
*(4 cal/g)*(4186 J/Cal)
= 5.46 E+13 J/yr


Fuelwood Prod = 4.47 E+03 m3 for 1988 (INEGI, 1990)
Energy (J) = (4.47 E+03 m3)*(0.5 E+06 g/m3)*(3.6 cal/g)
*(4186 J/Cal)
= 3.37 E+13 J/yr


Harvest = 3.39 E+04 m3 for 1988 (INEGI, 1990)
Energy(J) = (3.39 E+06 m3)*(0.5 E+06 g/m3)*(3.6 cal/g)*(4186 J/cal)
= 2.55 E+14 J/yr


14 ELECTRICITY (no exports reported):

Int. Combust.

= 6.94 E+06
= 6.14 E+05
= 7.55 E+06
= 2.70 E+13

KwH/yr (production
KwH/yr (production
KwH/yr (production
E+06 J/KwH)

for 1984, INEGI-II,
for 1984, INEGI-II,
within state)

Consumption = 8.65 E+08 KWH/yr = 3.11 E+15 J/yr (per cap est. for
the state in 1987; World Resources 90-91)
8.65 E+8 7.55 E+6 = 8.57 E+08 KwH/yr (what's probably imported)

15 MINERALS (no exports reported; includes Au, Ag, Pb & Cu):


= 2.97 E+02 MT/yr
= 1.75 E+05 MT/yr

for 1985 (INEGI, 1990)
(per cap est. for the state in
INEGI, 1990)


Soil loss =

Energy(J) =

9.64 E+10 g/yr (est. as 1.43% of Mex's. for 1986.
FAO, State of Agric & Food, 1989)
(9.6 E+10 g/yr)*(0.03 organic)*(5.4 kcal/g)*(4186 J/Cal)
6.54 E+13 J/yr


17 ELECTRICITY (refer to item number 14 for details):

Energy (J)

= 8.57 E+08 kwh/yr
= (8.57 E+08 kwh/yr)*(3.6 E+06 J/kwh)
= 3.10 E+14 J/yr




= 7.03 E+07 1/yr (for the state based on per capital
est. from Mex EMergy anal. for 1989 & BANCOMEX, 1990)
= (7.03 E+07 l/yr)*(4.4 E+07 J/l) (@ 44 E+06 J/kg & if
1kg = 11)
= 3.09 E+15 J/yr





= 1.304 E+10 ft3/y (for the state based on per cap.
est. from Mex EMergy analysis for 1989)
= (1.304 E+10 ft3/yr)*(1030 BTU/ft3)*(1054 J/BTU)
= 1.41 E+16 J/yr

= 1.31 E+04 B/day (for the state based on per cap-
ita est. for 1989; INEGI, 1990)
= (1.31 E+04 B/day)*(365 days/yr)*(6.1 E+09 J/B)
= 2.92 E+16 J/yr


20 C


Imports = 1.64 E+04 MT/yr (for the state based on per capital
est. from Mex EMergy anal. for 1989 & BANCOMEX, 1990)
Energy(g) = (1.64 E+04 MT/yr)*(l E+06 g/MT)
= 1.64 E+10 g/yr

22 MINERALS (Au,Ag,Pb,Cu):


Assumed import.
In grams

= 1.75 E+05 MT/yr (for the state based on per capital
est. from Mex EMergy anal. for 1989 & INEGI, 1990)
= 2.97 E+02 MT/yr for 1985 (INEGI, 1990)
= 1.75 E+05 MT/yr
= (1.75 E+05 MT/yr)*(l E+06 g/MT)
= 1.75 E+11 g/yr


Imports = 8.68 E+04 MT/yr (for the state based on per capital
est. from Mex EMergy anal for 1989 & BANCOMEX, 1990)
Energy (J) = (8.68 E+04 MT/yr)*(20% DW)*(1 E+06 g/MT)*(3.5 Cal/g)
*(4186 J/Cal)
= 2.54 E+14 J/yr



Energy (J)

= 2.56 E+04 MT/yr (for the state based on per capital
est. from Mex EMergy anal for 1989 & BANCOMEX, 1990)
= (2.56 E+04 MT/yr)*(20% DW)*(1E+06 g/MT)*(15.1E+03 J/g)
= 7.73 E+13 J/yr



Energy (J)


Energy (g)

= 8.02 E+02 MT/yr (for the state based on per capital
est. from Mex EMergy anal for 1989 & BANCOMEX, 1990)
= (8.02 E+02 MT/yr)*(1000 Kg/MT)*(9.4 E+06 J/Kg)
= 7.54 E+12 J/yr

= 6.95 E+04 MT/yr for 1989 (Plan Nayarit, 1990)
= (6.95 E+04 MT/yr)*(l E+06 g/MT)
= 6.95 E+10 g/yr


Imports = 1.81 E+04 MT/yr (for the state based on per capital
est. from Mex EMergy anal for 1989 & BANCOMEX, 1990)
Energy (J) = (1.81 E+04 MT/yr)*(l E+06 g/MT)*(15 E+03 J/g)
= 2.72 E+14 J/yr


Imports = 9.40 E+03 MT/yr (for the state based on per capital
est. from Mex EMergy anal. for 1989 & BANCOMEX,1990)
Total wt. (g) = (9.40 E+03 MT/yr)*(l E+06 g/MT)
= 9.40 E+09 g/yr


Dollar value =

EMergy (sej) =

1.19 E+09 $US (for the state based on per capital
est. from Mex EMergy anal.& Sum. Estad., 1989)
1.19 E+09 $US)*(3.32 E+12 sej/$ = Mex's EMergy/$ ratio)
3.95 E+21 sej

30 TOURISM (900,000 visited in 1990 (IV Inf.de G.del Estado, Ag, 1991):

Avg. daily expend. = 41.91 US$ 1990 (avg. stay of 11.3 days & expen-
ditures of 473.60 US$ per II Inf. de G. de Mex., 1990)
= (900,000)*($41.91/day)*(11.3 days)
= 4.26 E+08 US$




Energy (J)

1.15 E+05 MT for 1989 (Plan Nayarit, 1990)
-1.10 E+03 MT for state (based on per cap. natl avg)

1.14 E+05 MT assumed exported in 1989.

= (1.14 E+05 MT/yr)*(l E+06 g/MT)*(4 cal/g)
*(4186 J/Cal)*(0.22 protein)
= 4.20 E+14 J/yr

32 CASH CROPS (Agriculture & Forestry):

Exports (for 1989, Plan Nay., 1990):
TOTAL 4.08 E+04 MT for 1989 (Plan Nay, 1990)
Energy (J) = (4.08 E+04 MT)*(1 E+06 g/MT)*(3.5 Cal/g)
*(.1 dry wt)*(4186 J/Cal)
=5.98 E+13 J/yr


Exports = 2.53 E+03 MT for 1989 (Plan Nayarit, 1990)
Energy (J) = (2.53 E+03 MT/yr)*(l E+06 g/MT)*(4 kcal/g)
*(4186 J/kcal)*(0.22 protein)
= 9.32 E+12 J/yr


Exports = 2.49 E+04 MT/yr for 1985 (INEGI, 1990)
Energy (J) = (2.49 E+04 MT/yr)*(l E+06 g/MT)*(4.0 kcal/g)
*(4186 J/kcal)
= 4.17 E+14 J/yr


Value (Pesos)
Dollar Value
EMergy (sej)

= 4.48 E+12
= 1.67 E+09 $US (at 1989 parity of $2,686 pesos/US$)
= (1.67 E+09 $US)*(3.32 E+12 sej/$)
= 5.54 E+21 sej


Dollar Value = 4.26 E+08 $US for 1990 (IV Inf.de G. del Estado,
Ag, 1991; based on $473.60 as avg. amount spent
by each tourist as per II Inf de G. de Mex 1990)
EMergy (Sej) = (4.26 E+08 $US)*(3.32 E+12 sej/$)
= 1.41 E+21 sej

Table B-2. Summary of flows in Nayarit, 1985.

Solar EMergy Dollars
Variable Item (E18 sej/y) (E7 $/yr)

Renewable sources (waves & tides)

Nonrenewable sources flow within Nayarit

Dispersed rural source

Concentrated use

Exported without use

Imported fuels and minerals

Imported goods

Dollars paid for imports

EMergy value of goods and service imports

Dollars paid for imports minus goods

Imported services

Dollars received for exports

EMergy value of goods and service exports

Exported products transformed within Nayarit

Dollars received for exports minus goods

Exported services

Nayarit's Gross Domestic Product

World EMergy/$ ratio, used in imports

Mexico's EMergy/$ ratio

Total EMergy used within Nayarit



































3.80 E+12 sej/$

3.32 E+12 sej/$

5.46 E+21 sej/yr

Table B-3. Indices using EMergy for overview of Nayarit, 1985.

Item Name of Index Expression Quantity

Renewable EMergy flow

Flow from indigenous non-
renewable reserves

Flow of imported EMergy

Total EMergy inflows

Total EMergy used, U

Total exported EMergy

Fraction EMergy use derived
from home sources

Imports minus exports

Export to imports

Fraction used,
locally renewable

Fraction of use purchased

R 1.57 E+21 sej/y







(F+G+P2 I) (N2+B+PE3)





















-1.72 E+21 sej/yr




12 Fraction used, imported
service P2I/U

13 Fraction of use that is free (R+N,)/U

14 Ratio, concentrated to rural (F+G+P,21+Ni)/(R+No)

15 Use/unit area (2.8 E7 m2) U/(area of Nayarit)

16 Use per person (8.0 E5 pop.) U/population

17 Renewable carrying capacity
at present living standard (R/U)*(population)

18 Developed carrying capacity
at same living standard 8*(R/U)*(population)

19 Ratio of use to GDP, EMergy/dollar ratio:

(GDP: 73.6 E7 US$/yr) Pi = U/GDP
(GDP: 3.32 Ell Pesos/yr) PPI = U/GDP

20 Ratio of electricity to use (elec.)/U

21 Fuel use per person fuel/population










2.31 E+05 people

1.85 E+06 people

7.42 E+12 sej/US$
1.64 E+10 sej/p$


3.50 E+15


SECTION 3C: Water Resources Planning in the Bay of Banderas Basin

by Pamela Green


Statement of the Problem

Economic vitality and carrying capacity of developing regional watersheds are often influenced by the
interactions between agriculture, industry, and urbanization, and the need of each of these sectors for water. This is
particularly true in areas with arid climates. As each of the economic sectors increases in size, the demand for water
increases and a competition for water between sectors often results. Carrying capacity and economic vitality of a
region may be diminished as competition and decreasing water supplies result in increased costs of water extraction,
treatment and delivery. In addition to this increased demand for water there is often a concurrent increase in the
generation of wastes. The costs, both in technology and environmental deterioration, of treating and disposing of
wastes can place an added drain on the economy. Practices of improper disposal of wastes can reduce
environmental quality and further drain the local economy. Quantitative criteria are needed to choose between
alternative uses of water and decide which public policy options for water management will maximize economic
vitality. Public policy regarding water use and reuse that maximizes local economic vitality may be fostered using
techniques of energy analysis to gain perspective on the value of water in different applications. A water policy
which generates the greatest energy flux and dollar flow in the local economy may lead to the greatest economic
vitality. In this study, the role of water in the regional economy of Puerto Vallarta, Mexico was evaluated using
EMergy analysis to help determine policy options and future water use/reuse patterns.

Plan of Study

The carrying capacity of an area will be limited as water supplies and water quality are reduced due to
exploitation and misuse of regional water resources. Diminished availability of suitable water supplies can be
particularly debilitating in arid regions, where water is most limiting. The main objective of this project was to
evaluate the role of water in a regional system and the influence of a growing economy on water use and reuse and
allocation between sectors of the system. EMergy evaluation was used to determine the macroeconomic dollar
values of water to the economy for agriculture, urban, tourist and fishery sectors. Using the Bahia de Banderas
watershed basin as a case study, the specific goals of this project were: 1) to determine the value of water that
results from use in main sectors of the economy; and 2) to develop water policy options based on maximizing
regional productivity and minimizing economic and environmental costs.


The value of water and its contributions to an economy were analyzed in overview by first diagramming the
regional hydrologic system and sectors of the economy and evaluating all EMergy inputs to provide water as an
input to each sector. The value of water in its economic interaction was evaluated based on the economic
investments that its use attracted. EMergy contributions of water were expressed in macroeconomic dollar values.
Results of the EMergy analysis were compared to economic values for water derived from the literature, including
market value, the costs of energy required to provide water, and the marginal value of commodities produced from
Water policy options were formulated based on the results of the EMergy analysis and macroeconomic
water values calculated. EMergy analysis of the various options for water use and reuse required both economic
costs of alternatives and the environmental costs and benefits. Combined, these costs and benefits were compared
for the various alternatives and policy options. The choice of the Banderas Basin as a study site was driven by the
availability of data and the fact that it is under considerable development pressure. While only approximately one
half of the basin is within the state of Nayarit, and the majority of urban infrastructure is within the neighboring
state of Jalisco, the understanding gained concerning water-related policy in the basin will have applicability
throughout the coastal zone of Nayarit.

Site Description

The Banderas Bay watershed basin (Figure C-l) is located on the Pacific coast of Mexico at the extreme
southeast of the Gulf of California, between the parallels 200 25" north and meridians 1050 08" and 106 42". The
geographic limits are: Punta Litigu to the north, Valle de Banderas to the east, and Cabo Corrientes to the south.
The northern coast is situated in the state of Nayarit, stretching from Punta Litigu to the mouth of the Ameca River
and extending inward along the river valley on the north side of the Ameca. The areas to the south of the Ameca
and along the southern coast are located in the state of Jalisco.
The area can be divided into two types of terrestrial ecosystems, coastal mountains of the north and south
regions and the alluvial plain associated with the Ameca River valley extending inland. The coastal mountain
regions are an extension of the Sierra Vallejo and can be categorized as either high mountains (>250 m altitude)
with steep slopes or low mountains (<250 m altitude) with milder or staggered slopes.
The climate of the basin can be described as dry, subhumid and warm with summer rains. Average annual
precipitation in Valle Banderas is 1.12 m/yr, and average annual temperature is 26C. The typical season consists of
4 to 5 months of rain (June to Sept) with 29% of this occurring in the month of August. The dry season lasts 7 to 8
months. Puerto Vallarta tends to have higher annual precipitation (1.4 m/yr), with maximum precipitation occurring
in the month of September. Higher precipitation values are most likely a result of orographic effects due to the
city's position relative to the adjacent mountains.
Hydrologic systems of the basin can be subdivided into the rivers of the Sierra Vallejo and the tributaries of
the Ameca River. Groundwater recharge is generally greatest in the river valley and least in the higher reaches of
the mountains. As a result, a number of important aquifers are located in the region of the valley. There are


approximately 120 deep wells and 250 draw wells in the area that have an average depth of 59 m and an average
pumping depth of 13 m (SEDUE, 1990; SEAPAL, 1991). Annual recharge is estimated as 1.6 E+08 m3/yr in the
valley, calculated as 10% of total rainfall over the region (SEDUE, 1990; Roose, 1989). Extraction of water from
the aquifer mainly for urban or tourist consumption is 23.3 E+06 m3/yr for the valley and coastal areas of the basin
(SEDUE, 1990). The structure of drainage streams is very dense in the mountain areas draining directly into the
ocean, while drainage in the valley generally occurs through convergence to the Ameca. A total of six major river
basins drain the area, as shown in Figure C-1.
The coastal region is characterized by sandy beaches, bluffs and estuaries. The coastal area in the north
from Punta Litigu to Punta Negra is dominated by sandy beaches of marine origin. Extending from Cerro Careyeros
to Punta Las Cuevas are a series of bluffs and cliffs descending to the ocean. From Punta Plumeros to Punta
Destiladeras there extends a succession of sandy beaches interrupted by rocky formations with coral reefs offshore.
Between Destiladeras and Cruz de Huanacaxtle a natural corridor between the Sierra Vallejo and the ocean exists
where the lower mountains abruptly meet the sea forming steep cliff and limiting access to the coast. To the south
and east past Bucerias is the mouth of the Ameca river. Sandy beaches of terrestrial origin with the highest
recreational value in the area comprise the coastal area with a string of tourist developments along the length of the
beach on either side of the river mouth. On the southern side of the Ameca there exists an international airport
and the main marina which was transformed from the El Chino estuary. The remaining coastal area to the south is
comprised of sandy beach interrupted by tourist developments and the city of Puerto Vallarta. The beaches
generally diminish south of Mismaloya where the lower mountains abruptly meet the sea.
Land use in the region can be broadly classified as natural, agriculture and urban. Natural systems in the
area have been divided into the following categories (SEDUE, 1990): subperennial medium jungle, caducifolia low
jungle, subperennial medium jungle with palms, inundated jungle, mangroves, riparian wetlands, savanna vegetation,
beach vegetation, and secondary vegetation. Subperennial medium jungles are located in the Sierra Vallejo
mountains along principal streams with some traces occurring in the alluvial plain of the valley. Caducifolia low
jungles are located on the hills along the lower fringes of the Sierra Vallejo, generally in rocky or shallow soils, and
play an important role in preventing erosion of the soil. Palm-dominated subperennial medium jungles are located
in lower altitude humid and subhumid zones, generally in dry clayey soils, and are primarily found surrounding the
city of Puerto Vallarta. These systems are interspersed with agricultural areas between Punta Pantoque and Punta
Litigu and along the southern coast of the bay.
Inundated jungle and mangrove systems are found generally surrounding the lagoons north of the mouth of
the Ameca river. Riparian wetland vegetation includes all flora associated with the river and stream systems
including vegetation along the fringe, and submerged and floating aquatics. Savanna vegetation is found in dry, low-
altitude areas such as Punta Mita, and is characterized by sparse tree cover and well-drained soils. Secondary
vegetation is found throughout the region where natural vegetation has been disturbed by agriculture and forestry
Agricultural and pasture lands are found throughout the river valley. There are both temporal and
irrigated crop lands; the latter located adjacent to the Ameca River and the former towards the outer valley. In


many cases temporal cultivation is alternated with foraging pastures to provide maximum use of the land. Urban
areas in the region consist of the centers of population and the tourist developments. The towns in the valley
originated as centers for agricultural and livestock industries. Although they still serve these industries today they
are also centers of commerce and service in addition to housing the population. The average population of the
towns in the valley is approximately 40,000.
The city of Puerto Vallarta and a number of small towns are situated along the coastal fringe, and were
originally established as fishing villages. Although some of the towns in the northern area of the bay are still heavily
involved with fishing activities, the larger cities are primarily geared towards tourist activities and services. The
population of Puerto Vallarta is approximately 150,000 permanent residents. A variety of tourist developments
including hotels, motels and bungalows are also found throughout the coastal areas and service over one million
tourists each year. The equivalent yearly population including tourists and permanent residents is approximately
170,000, with tourists comprising 8% of the population.
The largest industry in the area is tourism, bringing in 600 million dollars per year. Agriculture, livestock
and fishery industries also contribute to the economy but to a much lesser extent. All fuels, electricity and many raw
materials (concrete, plastics, etc.) are imported to the region from larger metropolitan areas such as Tepic and

Approaches To Valuing Water Resources

Resource Economics Approach
Traditionally, resource economics has determined the value of water in terms of the marginal value of the
commodity. Marginal value is defined as the benefits received for an increase in water supply minus any marginal
costs for treatment and delivery of the water. Marginal values are often estimated from water demand curves as the
willingness to pay for the last unit of water delivered or the last increment of supply needed to meet consumer
demand. Marginal values are also derived from water production functions as the increase in marginal physical
productivity supported by an increment in water input to the process. Market demand curves and water production
functions for waters consumed in agricultural, municipal and industrial processes can be determined directly from
market-clearing prices for varying levels of water demand and use. For public goods not directly represented in the
marketplace (such as recreation, aesthetics and waste assimilation) marginal values and demand curves must be
simulated by other means such as travel costs or questionnaires.

Agriculture and urban value. According to traditional economic theory, the marginal value of irrigation water is
equal to the amount of money paid for the last unit of water delivered for a given water supply level. The U.S.
Bureau of Reclamation (1985) estimated the marginal value of irrigation water in the John Day Basin of north
central Oregon to be between $10 and $24 per acre-foot. A higher estimate of $95.09/ac-ft was determined by
Kulshreshtha (1991) for the south Saskatchewan irrigation district. Thus, although agricultural water values may
vary they tend to be low, generally less than $100 per acre-foot. Gibbons (1986) states that these marginal values for

irrigation are unique for different crops and may vary according to site location, which may contribute to the wide
range of water values seen in the literature.
Marginal values for municipal water consumption are likewise determined as the cost of delivering the last
unit of water to the municipality. Gibbons (1986) estimated marginal water values for municipal use to range
between $4 and $225/ac-ft for Tucson, Arizona, and between $6 and $358/ac-ft for Raleigh, North Carolina. She
contends that these marginal values vary both seasonally and according to location. Marginal values for water supply
augmentation were calculated by Griffin (1990) for 221 Texas communities, and varied between $0 and $4000/ac-ft.
He contended that value was a function of the economic and physical conditions faced by each community and
varied with the season, the water source (surface or ground water) and the population growth rate. Typically,
approaches to economic valuation of water have concentrated on off-stream uses, dictating that water be removed
from the system and put to beneficial use (usually with tangible, financial returns) in order to gain priority rights.
This approach does not account for the very real values of in-stream uses associated with recreation, waste
assimilation, and ecological processes.

Recreation and aesthetics. Several methodologies have been developed to simulate market values for public goods
not directly represented in the market such as water-based recreation, aesthetics and wastewater assimilation. In
these methods, marginal values can be estimated either by indirectly assigning a price to the water through an
associated variable such as travel costs and admission fees, or by directly questioning the consumers as to their
willingness to pay for recreational gains resulting from changing water levels (contingent valuation method). A
number of approaches have been taken to estimate the value of water for recreation and aesthetic purposes
(Gibbons, 1986; Howe, 1971; Johnson, 1988; Lant, 1991). The end uses of recreational waters have a value derived
from the provision of utility to the consumer. These uses include swimming, boating, fishing, picnicking, bird
watching, beach walking, sightseeing, etc. Howe (1971) states there are also values of water which exists
independent of use such as the value of the natural resource left in a pristine state for future use, for the benefit of
future generations, or simply for the knowledge of its existence.
With increased urbanization and development the demand for recreational waters has increased while the
supply has decreased or been altered, resulting in higher values for the water. Considering that market prices for
this commodity are not readily available, the value for recreational waters must be estimated using other means
outside of the market. Some traditional approaches to estimating recreational water value have been based on
entrance and participation fees, travel costs, questionnaires and consumer surveys, or taking the water value as a
portion of the total value of the recreational site (Gibbons, 1986; Howe, 1971; Johnson, 1988; Lant, 1991).
Marginal values can be determined from travel costs as the change in visitation as a result of flow levels.
Marginal values can alternatively be derived from consumer surveys through responses to questions of how much a
person would be willing to pay over changing water levels. In streams, for example, Gibbons (1986) estimated
maximum marginal values for fishing, shoreline recreation and rafting along the Colorado River to be $16/ac-ft,
$11/ac-ft and $6/ac-ft, respectively, occurring at low flows. In addition, she estimated maximum marginal values for
water for recreational fishing for a number of areas in the United States based on dollars per visitor-day. Values


ranged from $4 to $29 per user day depending on the site (stream vs. reservoir) and the type of species sought.
Johnson (1988) determined the value of an additional acre-foot of water in the production of recreational steelhead
fishing to be $2.36. However, the value of this water increases if it is used for other purposes such as irrigation at a
point downstream, in which case the value of the water will be equal to the sum of the marginal values for
recreation and irrigation.
Gibbons (1986) estimated values for fish hatchery water ($23/ac-ft in the Trinity River of California), as
well as water for spawning ($40/ac-ft for the Toulumne River in California). In addition, values of wetland waters
for fishing, waterfowl, hunting and recreation have been estimated by Gibbons (1986) for Michigan coastal regions
($590/ac-ft), Virginia fish production ($190/ac-ft), and recreational fish and wildlife in the Charles River,
Massachusetts ($27/ac-ft).
Lant (1991) suggests that water value alone does not accurately reflect the intrinsic value of lakes and rivers
for recreational uses. Rather, the geomorphologic, ecological and aesthetic characteristics of the site represent the
real value for recreators. The degree to which water quality and hydrologic regime (water level, flow rates)
contribute to these characteristics determines the value of the water to the recreation site. In addition, water quality
as perceived by the recreator was found to be much less important than aesthetics of the site and the quality of
fishing. Water quality and flow regimes were found to be more important in terms of their contributions to the
ecology and aesthetic qualities of the site. Since different approaches have been used to reach common values,
problems arise in comparing average values such as admission fees or fishing license fees to marginal values based
on willingness to pay for the recreation, and comparing values having differently derived denominators (e.g., $/flow
volume, $/visitor day).

Waste assimilation. Water also has a value associated with the dilution and assimilation of industrial and municipal
wastewaters. Typically, the value of water for waste assimilation is based on either waste treatment costs forgone or
downstream damage avoided (Gibbons, 1986). This value is often a function of the treatment level required and is
unique to each type of pollutant removed or diluted. Gibbons (1986) gives marginal values for dilution and
simulation of biochemical oxygen demand (BOD) in river basins, calculated by dividing the marginal cost of
increasing treatment from 35% removal to 70% removal for municipal effluent and 50% for industrial effluent, by
the amount of water needed to dilute the remaining BOD. Values range from $0.2/ac-ft for river basins in the
Pacific Northwest to $6.81/ac-ft for river basins in the lower Missouri region. Gibbons (1986) also determined
marginal values for the least-cost contribution of treatment and dilution, where cost minimization treatment levels
were based on the initial assimilative capacity of the water, the amount of waste discharged and the potential for
flow augmentation. Estimated values range from $0.48/ac-ft for the Pacific Northwest to $6.98/ac-ft in the upper
Arkansas-White-Red River basin region. Typically, the largest dilution values were found in river basins with high
waste loads and low flows, where high levels of treatment are required.
In addition to BOD, marginal values can also be estimated for treatment and dilution of a number of
pollutants including nitrogen, phosphorous, bacteria, viruses, heavy metals and toxic organic. Brown (1990)


estimated the value of water for dilution of total dissolved solids in the Colorado River Basin to be $11/ac-ft, based
on the cost savings to water users.
The distribution costs of alternative effluent application systems is a contributing factor in predicting the

value of water for waste assimilation. Boyle (1976) determined a cost estimating procedure for the various land and

wetland effluent application systems based on the following parameters: construction costs, land costs, power costs,

operation and maintenance, design flow in mgd, and amortization costs. Total cost for various application systems

were calculated as the sum of all component costs per 1000 gallons of effluent. In Waldo, Florida, costs were

estimated to be $0.42/1000 gallons for wetland discharge, $1.07/1000 gallons for advanced physical/chemical

treatment, and $0.63/1000 gallons for spray irrigation. Boyle (1976) also compared the costs of disposal into a

cypress dome ($0.71/1000 gallons) to disposal into a wetland strand ($0.22/1000 gallons) for the Orlando Naval

Training Center.

Marginal value of a commodity varies in the short term as inputs become scarce or abundant causing prices

to vary. Therefore value is a function of the perceived utility of the commodity among the users. Lynne (1974)

states that maximum economic efficiency of water use is reached when the marginal values of water in all sectors are

equal. According to this view, water will have the highest dollar value where it is perceived to be the most needed

or scarce, and have a lower value where it is abundant and not a limiting resource. Since people tend to view

services provided by the environment as "free of charge", it is likely that market values for water and other natural

resources not requiring a large amount of processing will be characteristically underpriced. In addition, this belief

fails to take into consideration market values that are not reflected in the market prices, such as recreation and

aesthetic values, contributions to fisheries, pollution costs, benefits to labor that would otherwise be unemployed,

and market prices that have been manipulated to misrepresent real values in order to be more competitive on the

world market. Also not represented in the market value of a commodity are the secondary benefits and costs to

other parts of the economy that are influenced by its production; for example, greater employment opportunities as

a result of increased crop production due to irrigation practices.


An EMergy Theory of Value

As defined previously, EMergy is a scientific-based measure of wealth which places raw materials,

commodities, goods and services on a common basis of the amount of energy required to produce each item (Odum,

1991). An EMergy theory of value is a "donor"-based system, where the value of the resource is a function of the

outside inputs used to support the network that ultimately produces the resource. Since this approach bases value of

the product on the energy inputs to the system, including natural, un-monied inputs, it contrasts with typical

economic approaches which determine value according to market prices (Gibbons, 1986; Howe, 1971; Lynne, 1986;

Grubstrom, 1988). The EMergy value of an item is measured by what is required from the donor sources to

generate that item, where all inputs to the process are expressed in a common energy basis (energy of the same

type). When expressed in common units of source energy, the units are called EMergy, and given the name of the

source. In this study, solar EMergy was used as the common energy basis.

Odum (1986) states that the EMergy value of water is dependent on its place in the hierarchy of the water

cycle. The lowest EMergy value for water is found in precipitation. As water converges in rivers, groundwater or

lake storage its EMergy value increases. The energy of water can be characterized as geopotential, chemical

potential, wave and tide energies, geothermal potential, and the energy in suspended sediments in the water. The

degree to which each contributes is dependent on the way in which water contributes to the economy. For example,

Odum et al. (1987a) used the geopotential energy of water as a measure of a river's contribution to hydropower

activities. In an analysis of the coastal zone of Texas, Odum et al. (1987b) based the energy contribution of water

sources for irrigation and municipal use on the chemical potential of the water.

The chemical potential of water has also been employed to measure the energy input of water to fisheries

(Odum et al., 1987b; Odum and Arding, 1991; Brown et al., 1991). Tidal and wave energies of nearshore, waters as

well as the energy of suspended sediments in discharging rivers have also been demonstrated to contribute to

fisheries production but often to a lesser extent (Brown et al., 1991). Odum et al. (1987a) valued a river's

contribution to coastal wetlands in terms of the energy of suspended sediments and organic matter carried by the

river and deposited in the wetland, building structure. In each case, the EMergy inherent in the water is combined

with the EMergy of human inputs (fuels, goods and services) utilized in processing the resource, to calculate the

EMergy value of the water commodity.


The value of water for waste assimilation may be measured by the amount of production the nutrient rich

effluent supports relative to the amount of outside EMergy required for treating the wastewater. Mitsch (1976)

evaluated nutrient disposal alternatives, comparing the changes in EMergy flows caused by disposal of secondarily-

treated effluent. Energy flows were given in fossil fuel equivalents and were determined for disposal in a lake

system, a cypress dome and a tertiary treatment facility. The change in sunlight-based energy flow representing

natural energy supporting the systems was found to be 2 E+08 and 7 E+08 (fossil fuel equivalents/yr) for the lake

and cypress dome disposal methods, respectively. The change in fossil fuel work representing human fuels, goods

and services supporting the treatment operations were calculated as 11.6 E+08, 14.7 E+08 and 25 E+08 (fossil fuel

equivalents/yr) for the lake, cypress and tertiary treatment disposal systems, respectively. The cypress and lake

systems utilize natural low-quality energies such as primary production to assimilate and treat the effluent, and

amplify these energies with purchased high-quality energies to augment treatment and enhance production of wood

products and aquatic biomass. The tertiary treatment method, on the other hand, is supported primarily by

purchased high-quality energies that do not interact with lower quality natural energies. Since natural systems rely

mostly on "free" natural inputs and less on purchased high quality energies, this would suggest that these natural

systems may yield a higher realized work service per purchased energy invested.

Odum (1990) suggested that the availability of an environmental product such as water also contributes to

the economy by attracting imported human resources such as fuels, to facilitate development in the area and

promote economic growth. Abundant sources of water having characteristically low market prices attract

developments to use the water, which in turn brings in additional goods and services to build the economy. When

water is scarce, however, more outside energy is needed to retrieve the resource and its contribution to the economy

decreases. The economic viability of an area may be predicted by the ratio of attracted EMergy to environmental

EMergy, which can be used as an index for potential intensity of development.

Environmental resources are often viewed as being "free of charge", where the money paid for resource

acquisition reflects the human work carried out to obtain and process the raw materials and not for the work of the

environmental systems that produced them. Since there is no exchange of money between the economy and the

environment, prices in the market place will not accurately reflect the value of environmental inputs to the economy,

which also serves to further reinforce society's perception of the resources having low value. Odum et al. (1987b)

found that macroeconomic EMergy values for water inputs to the different sectors of the Texas coastal zone


economy were characteristically much higher than the actual money paid for the water itself. Macroeconomic values

were determined for rain, river and groundwater ($0.035/m3, $0.09/m3, $0.25/m3, respectively), which are not

represented in the marketplace. The macroeconomic values determined for agricultural ($0.44/m3) and domestic

($1.16/m3) waters were found to be 11 and 1.5 times greater than the market values for these commodities.

According to EMergy theory, those systems which will succeed and be sustainable over the long-term

increase and maximize their use of available energy (Odum, 1992). Systems maximize use of energy by drawing

more resources, increasing efficiency, and reinforcing processes through feedback mechanisms and outside imports.

Both ecologic and human systems self-organize through trial and error to select for those patterns which out-

compete and survive by securing the most EMergy, and allocating it to uses that reinforce production. Human

systems use creativity and choice to discover the optimum patterns for maximizing EMergy for the long-term,

macroscopic well-being of the economy and environment. Basing policy decisions on EMergy evaluations which

predict maximum wealth founded on scientific principles can result in better public policy choices with far less trial

and error.

The results of an EMergy analysis can be used to compare the contributions of items to an economy and

propose policy suggestions based on those patterns which are the most efficient and sustainable over time. In the

case of an environmental commodity, such as water, its contribution to the economy can be measured in three ways:

(1) EMergy cost, (2) the amount of outside energy the item attracts to the area, and (3) the degree to which the use

of the commodity maximizes economic efficiency.


An energy systems overview of the role of water was developed for the Bay of Banderas watershed basin,

including a comparison of water use between main economic sectors and an analysis of both temporal and spatial

water resource availability and use in the basin. Energy systems diagrams were constructed for the entire region as

well as for each main sector. Using these diagrams, EMergy analysis tables were assembled to document the main

energy flows supporting the systems. From these tables appropriate EMergy indices were compiled to compare

EMergy contributions between sectors.


Regional EMergy Analysis of the Banderas Basin

Overview Systems Diagram

Figure C-2 shows a systems diagram of the Banderas Bay watershed basin. The major subsystems in the

basin can be broken down into four groups, each having a unique contribution to the system: natural lands,

agricultural lands, nearshore zone, and urban areas. Natural lands include uplands, forests and pastures, which

support fuelwood production, forest extraction and livestock production. These natural lands also contribute to the

aesthetic and scenic qualities of the basin (represented by the image tank) which draws tourists to the area.

Agricultural lands consist of those areas in the valley supporting agricultural production. Crop production supports

local farm workers and distributors in the urban areas, as well as providing a needed food supply. Irrigation water is

derived from both surface water (Ameca River) and groundwater sources. The nearshore zone is comprised of the

pelagic ocean, beaches and estuaries which support fishery production as well as contribute to tourism. The bay

receives an influx of fresh water containing nutrients and organic matter, in the form of suspended sediments from

the six major rivers which discharge into the bay. These nutrient-laden waters sustain productivity of the bay

ecosystem supporting the fishing industry upon which local fishermen depend for their livelihood. The bay, beaches

and estuaries are also a major element in attracting tourists who utilize these areas for sportfishing, sailing,

swimming and the aesthetic and scenic qualities.

The urban areas are the cities, towns and tourist developments within the basin. The urban areas in the

river valley are mainly supported by agricultural activities while the coastal cities and towns are supported by tourism

and the fishing industry. Revenues received from agriculture, fisheries and tourism are used to purchased goods and

services from outside the region to enhance productivity in the economy. The larger city of Puerto Vallarta itself is

a tourist attraction with its traditional Mexican architecture, cobblestone streets and many tourist shops. In addition,

many urban areas produce large amounts of wastes which are generally treated and discharged into the major rivers

or directly into the bay.

Water enters the watershed system mainly through rainfall and river inflow from the upper reaches of the

Ameca River. The majority of the rainfall evaporates, while the remainder exists in the system as surface flow to the

bay or infiltrates to the groundwater. Rain that falls on the land travels over the surface to the bay or to the rivers

that discharge into the bay, carrying with it sediments and other materials washed from the surface. Some of this


surface runoff as well as some of the river water infiltrates to the groundwater. During certain parts of the year

water is diverted from the Ameca and used for crop irrigation. In some cases groundwater is also pumped for

irrigation purposes, although to a lesser extent. Urban areas pump large amounts of groundwater for human

consumption and general use. The amount of water pumped varies seasonally according to the number of tourists

visiting the area. Wastewaters from cities, towns and tourist facilities are discharged to the bay or to the rivers

which empty into the bay.

Regional EMergy Table

A comprehensive evaluation of the resource base of the regional economy for 1989 is given in Table C-1.

The primary renewable resources contributing to the system include sun, rain, wind, waves, tide and river inflow

from the upper reaches of the Ameca River. Table C-1 lists the renewable resources and their solar EMergy

contributions to the system. The total renewable EMergy flow was calculated as the sum of the rain chemical

potential, river chemical potential and tide. All other sources were excluded to avoid double counting, as they were

derived from similar global processes.

Indigenous renewable energy within the system is derived from agriculture, livestock, fisheries, fuelwood

production and forest extraction. The major nonrenewable sources within the system were topsoil erosion and water

associated storage. It should be noted that all of the nonrenewable sources in the system were derived from

renewable resources, and therefore their EMergy contributions to the system had already been counted. Imported

fuels, goods and services were larger than indigenous sources. The largest of these imports were purchased inputs

for tourism (construction materials, food, liquor), EMergy in tourists, electricity and fossil fuels. The primary export

from the system was tourist service, calculated as the total dollars spent by tourist per year. Also exported were cash

crops, fishery products and livestock, comprising about 15% of total exports.


EMergy Indices for Regional Analysis

Figure C-3 is a summary diagram of the Banderas Basin showing inflows and outflows from the system, as

listed in Table C-2. Table C-3 lists a number of calculated indices based on the flow values of the system. The

purchased inputs to the system are approximately 5 times larger than the natural inputs (item 17, Table C-3). In

fact, the fraction of EMergy use derived from home sources is about 16% (item 7, Table C-3) with the remaining

84% being purchased from the outside. Item #14 in Table C-3 shows that about 49% of purchased imports are for

tourist services. A comparison of total imports to exports reveals that imports are slightly higher than exports for

the basin system (items 8 & 9, Table C-3). However, comparing tourist imports to exports shows exports of tourist

services are larger than purchased imports supporting the tourist industry (items 10 & 11, Table C-3).

Comparing similar indices for the country of Mexico (Table C-3, column 5) with those calculated for

Banderas Bay reveals that use per unit area, use per person (based on equivalent population), EMergy to dollar

ratio and purchased to free ratio were all much higher for the Banderas Basin than those found for the nation. The

net EMergy yield ratio was found to be lower for the basin than for the country in general.

EMergy Value of Water in the Banderas Basin

Regional Overview

Given in Figure C-4 is a summary of water flows and use in the Banderas Basin. The energies,

transformities, and EMergy values for each of the numbered water flows are listed in Table C-4. Rainfall enters the

basin and is either evapotranspired (70%), runs off the landscape into surface water storage (20%), or recharges

ground water storage (10%). Surface water includes the nearshore waters of the Bay, and thus ocean currents are

shown flowing into and out of the system with no net exchange of water. Water from the upper reaches of the

Ameca River not included in the study area are shown as an input to the surface water system of the basin. Surface

water has an exchange with ground waters; however, the net exchange is not known but assumed to be negligible.

Evaporation from surface waters is shown leaving the system.

Groundwater recharge was estimated as 10% of rainfall from analyses by SEDUE (1990) and Roose et al.

(1989). The overall storage of ground water was estimated from SEAPAL (1991) as 6.73 E+10 m3 for an average

aquifer depth of 59 meters. The total volume of pumping water for an average pumping depth of 13 meters was


estimated to be 1.5 E+10 m'. The turnover time of the aquifer calculated from a recharge rate of 1.6 E+8 m3/yr

was found to be 414 years for the total depth and 93 years for the average pumping depth. Yearly extraction of

groundwater for agricultural and municipal uses is estimated as 6.85 E+07 m3/yr (SEAPAL, 1991; SEDUE, 1990) or

43% of the total yearly recharge, resulting in an adjusted recharge rate after extraction of 9.4 E+07 m3/yr.

Both ground water and surface water are used in the various economic sectors of the basin. The total use

was estimated by SEDUE (1990) as 1.97 E+08 m'/yr and 2.33 E+07 m3/yr for agricultural and urban uses,

respectively. The EMergies of surface and ground waters prior to extraction are listed in Table C-4 along with their

values following extraction, processing and delivery, denoted as Groundwater Use and Surface Water Use in items 3

and 4, respectively.

The EMergy value for raw wastewater was calculated in Table C-1 as the sum of EMergy in consumer

water and delivered foods while the transformity was determined as the EMergy divided by the energy in the

wastewater. Similarly, the EMergy in treated wastewater was calculated as the EMergy inputs of consumer water,

foods and treatment expenditures and the transformity was given as EMergy inputs divided by energy in the treated

water. Based on transformities, treated wastewater has more EMergy per unit water input than does raw

wastewater. In addition, treated wastewater has a higher transformity than processed surface and ground waters

used in municipal and agricultural processes. Economic interaction (line 6, Table C-4) measures the production in

the region supported by water inputs. EMergy was calculated as the total EMergy inputs to the system, while the

transformity was calculated as total EMergy inputs divided by energy in the delivered surface and ground waters.

Subsystem Evaluation of Water

Four sectors (agriculture, urban, tourist, fisheries) of the economy were evaluated, to determine the

EMergy of water and its value in economic interactions.

Agriculture. The EMergy analysis of irrigation water and the supported agricultural production was based on the

total hectares of irrigated agricultural land in the basin (7563 Ha). Irrigated agricultural lands produce 4.55 E+4

MT of crops per year including maize, rice, beans, tobacco, mangos, and other fruits and vegetables. Eighty percent

of all irrigation is derived from river sources; therefore, irrigated agricultural lands are generally located in close

proximity to the Ameca River. The total volume of water extracted from the river and, to a lesser extent,


groundwater sources is approximately 1.97 E+08 m3/yr. More than half of this water is lost to evaporation or

seepage before it reaches the crop lands.

Figure C-5 represents the energy flows and interactions for the agricultural production system in the

Banderas Basin. Water is delivered to the area through rainfall and the interaction of river and groundwater with

pumps, irrigation ditches and human services. Nutrients are delivered to the soil along with the river water and the

addition of fertilizers. Low quality solar energy interacts with soil water, soil nutrients and human services in the

production of the crop. Additional human services are required to transport the crops to the market place for sale.

Pesticides are imported to the system to decrease the number of insects feeding on crops. Exported crops are

exchanged for money from the outside market, which is used to purchase electricity for pumping water, fertilizers,

pesticides and human services, which feed back to support agriculture production.

Annual flows of EMergy through the subsystem are evaluated in Table C-5, and summarized in Figure C-6.

Each of the inflows of water--purchased inputs for irrigation, other purchased inputs to crop production and crop

yield--shown in Figure C-5 as sources are evaluated. The EMergy in source water totals 65.1 E+18 sej/yr, while

purchased energy supporting the irrigation system was 5.4 E+18 sej/yr, or about 9% of the total EMergy of

irrigation water. The total EMergy in irrigation water (70.5 E+18 sej/yr) was calculated as the sum of the EMergy

in the source water and purchased inputs. The irrigation water accounts for about 55% of the total inputs to

agriculture in the Banderas Basin. The transformity for irrigation water was calculated as 7.26 E+04 sej/J, the total

EMergy input to the irrigation water divided by the energy in the water delivered. The EMergy in the crop yield

(129.8 E+18 sej/yr) was calculated as the sum of all EMergy inputs to the system, while the transformity of crop

yield was calculated as the total EMergy in the crop yield divided by energy in the crops (3.0 E+05 sej/J).

Fisheries. The average yearly catch from the Banderas Bay fishery is 1.76 E+03 MT/yr. Average yearly discharge

of river water into the bay is 1.55 E+09 m3/yr. Figure C-7 represents the energy flows and interactions for the

fisheries production system in the Banderas Basin. Water enters the bay through rainfall, river discharge, tidal

exchange and ocean currents. No human interaction is needed in delivery of water to the system. Nutrients are

carried to the bay along with river water and exchange with the open ocean through tides and currents.

Phytoplankton utilizes low quality solar energy and nutrients for primary production; phytoplankton production

supports the fishery by providing a basis for the food chain. Human services, boats and fishing equipment interact


with the fishery to catch fish and bring them to the market. The fish catch is exchanged for money from the outside

market which is used to purchase fuels, equipment and human services which feed back to support the fishing


Annual flows of EMergy through the subsystem are evaluated in Table C-6 and summarized in Figure C-8.

Each of the inflows of water, purchased inputs for fishing, and fishery yield shown in Figure C-7 as sources are

evaluated. The EMergy in source water from the river totals 319.7 E+18 se/yr. No purchased energy is required for

transport or delivery of this water. River water input to the bay accounts for about 99% of the total inputs to

fisheries production in the Banderas Basin. The transformity for fisheries water was calculated as 3.67 E+05 sej/J,

which is the total EMergy input to the fisheries water divided by the energy in the water delivered. The EMergy in

the fisheries yield (327.1 E+18 sej/yr) was calculated as the sum of all EMergy inputs to the system while the

transformity of fisheries yield was calculated as the total EMergy in the fisheries yield divided by energy in the yield

(5.04 E+06 sej/J).

Urban and Tourist Sectors. The EMergy analysis for municipal water includes water values for both urban and

tourist sectors, since each derives its water from the same sources and uses the same facilities to treat and deliver

the water. Eighty-five percent of all municipal water comes from groundwater sources. The total volume of water

extracted for municipal use from groundwater and, to a lesser extent, the river is approximately 2.33 E+07 m3/yr.

Annual flows of EMergy for municipal water production are evaluated in Table C-7. Each of the inflows of water

and purchased inputs for municipal water shown in Figures C-7 and C-8 as sources are evaluated. The EMergy in

source water totals 11.5 E+18 sej/yr, while purchased energy supporting the municipal water system was 38.2 E+18

sej/yr, or about 77% of the total EMergy of municipal water. The total EMergy in municipal water (49.7 E+18

sej/yr) was calculated as the sum of the EMergy in the source water and purchased inputs. The transformity for

municipal water (4.31 E+05 sej/J) was calculated as the total EMergy input to the municipal water divided by the

energy in the water delivered.

Purchased inputs to the urban sector other than for municipal water were given in Table C-l, and include

fuels, electricity and goods and services supporting the urban economy. Figure C-9 represents the energy flows and

interactions for the urban sector of the Banderas Basin economy. Water is delivered to the urban population in

potable form from river and groundwater sources using fuels, electricity, goods and services. Municipal water


supports commercial production in the region both directly and indirectly,. Yield from commercial activities is

exchanged for money from the outside market, which is used to purchase fuels, equipment and human services that

feed back to support the urban economy and water treatment and delivery.

Annual flows of EMergy through the urban subsystem are evaluated in Table C-7 and summarized in

Figure C-11. Inputs from municipal water, other purchased inputs to the urban economy, and urban yield shown in

Figure C-9 as sources are evaluated. The municipal water accounts for about 9% of the total inputs to the urban

economy in the Banderas Basin. Other purchased inputs to the urban sector total 499.8 E+18 sej/yr, which is about

ten times larger than the inputs received from the municipal water. Total urban EMergy (549.5 E+18 sej/yr) was

calculated as the sum of all EMergy inputs to the system. The EMergy in exports from the urban sector (301.7

E+18 sej/yr) was calculated as the EMergy in cash crops, fisheries products and livestock exported.

Purchased inputs to the tourist sector other than for municipal water are fuels, electricity and goods and

services supporting the tourism industry. Figure C-11 represents the energy flows and interactions for the tourist

sector of the Banderas Basin economy. Water is delivered to the tourist population in potable form from river and

groundwater sources using fuels, electricity, goods and services. Municipal water delivered to tourist facilities

supports the tourism industry in the region. Yield from tourism is exchanged for money from the outside market,

which is then used to purchase fuels, equipment and human services which feed back to support the tourist industry

and water treatment and delivery.

Annual flows of EMergy through the tourism subsystem are evaluated in Table C-7, and are summarized in

Figure C-12. Inputs from municipal water, other purchased inputs to the tourism economy and tourist yield shown

in Figure C-10 as sources are evaluated. The municipal water accounts for about 2.4% of the total inputs to the

tourism economy in the Banderas Basin. Other purchased inputs to the tourism industry total 2043.9 E+18 sej/yr,

which is far greater than the input received from the municipal water. Total tourism EMergy (2093.6 E+18 sej/yr)

was calculated as the sum of all EMergy inputs to the sector. The EMergy in exports from the tourist sector (1977.4

E+18 sej/yr) was calculated as the total EMergy in tourist dollars spent per year.

EMergy Indices for Subsystem Analysis

Figure C-13 represents an aggregated diagram depicting the EMergy inflows and outflows for any of the

subsystems, emphasizing EMergy contributions of water to the subsystem economy. EMergy indices were calculated


based on the labelled flow paths in Figure C-13 for each of the subsystems, and are given in Table C-8. Items 1

through 8 in Table C-8 represent indices describing the water systems for each subsystem, including renewable

(natural) and purchased inputs needed for the processing and delivering of water supplies.

Renewable EMergy inputs to water for each of the subsystems were determined, to compare the extent to

which the natural systems contribute to water production. Renewable EMergy inflows to agricultural and fisheries

water were much higher than those for municipal water for urban areas and tourists. The flow of imported EMergy

for water production represents the attracted EMergy to the area, including imported fuels, goods and services.

Municipal waters for urban areas and tourists have the greatest attracted EMergy, while agriculture and fisheries

have the least. In fact, water for fisheries requires no purchased inputs, since water enters the system from river

discharge and tidal exchange with no need for human interaction.

The EMergy values of delivered water were calculated for each subsystem as the sum of the renewable and

imported EMergy inputs, and are given in line 3. EMergy water value was found to be highest for fisheries, followed

by agriculture and municipal water. The transformities of water for each sector were calculated in the subsystem

analysis tables, and are given in line 4. The transformity for municipal water was found to be the highest, followed

by fisheries water and agricultural water.

The fraction of EMergy used in the supply of water attributable to renewable and purchased inputs are

given in lines 5 and 6. Fisheries and agriculture have the highest percent attributable to renewable inputs and

municipal water has the highest percent attributable to purchased inputs. An investment ratio was calculated as

purchased divided by renewable EMergy inputs for water supply in each of the subsystems. The municipal water

supply system was found to have the highest purchased-to-free ratio, and the agricultural water system had the

lowest. The investment ratio for fisheries water is given as zero since no imported EMergy is needed to supply

water to the system.

Water yield ratios were calculated for the water systems in each sector as the EMergy in the delivered

water divided by the EMergy in purchased inputs to the water system, and was found to be greatest for agricultural

water and least for municipal water systems (line 17). The EMergy yield ratio was not calculated for fisheries water,

since no purchased inputs were used in delivery of the water.

Items 9 through 19 of Table C-8 represent indices describing the production and economic activities of each

sector, including contributions from water and purchased inputs to support subsystem processes. Flows of purchased


EMergy for each subsystem (not including purchased imports for water processing) are given in line 9. Tourism has

the largest amount of imported EMergy, followed by the urban sector, agriculture and fisheries. Likewise, the total

flows of imported EMergy (purchased imports for water plus all other purchased inputs to the system) as well as

total EMergy use in each subsystem are highest for tourist and urban sectors and lowest for agriculture and fisheries


EMergy in exports from each subsystem is given in line 12, with the highest amount of EMergy being

exported from tourist and urban sectors. The percent of total EMergy use attributable to water inputs was

calculated for each sector, and is given in line 13. Sectors with lower amounts of purchased EMergy, such as

fisheries and agriculture, have a higher percent of their EMergy attributable to water inputs, whereas those with

larger purchased inputs have a lower percent of their EMergy attributable to water inputs.

The fraction of EMergy used in the production or economic processes attributable to renewable and

purchased inputs are given in lines 14 and 15. Fisheries and agriculture have the highest percent attributable to

renewable inputs, and municipal water for urban areas and tourism has the highest percent attributable to purchased

inputs. Line 16 shows a purchased-to-free investment ratio for each sector, with fisheries and agriculture much

lower than the tourist and urban sectors. An EMergy yield ratio for each subsystem is given in line 17. The greatest

yield per purchased inputs occurs for the fisheries sector, followed by much lesser values for the agriculture, tourist

and urban sectors. The marginal macroeconomic value of water was calculated as the EMergy in the yield divided

by the EMergy in raw water (line 18) or delivered water (line 19) supporting the sector economy, and is useful in

determining the contribution of water to the subsystems' economy. The tourist sector was found to have the highest

marginal macroeconomic value of water, followed by the urban, agriculture and fisheries sectors.

Marginal Effects of Water Increases on Net Yield

The effects of additional water supplements to each subsystem economy were determined by increasing the

amount of water to each system by 5% increments and calculating the net yield supported by the increase. Net yield

was calculated as the sum of all EMergy inputs to the sectors for every increment in water supply. Yield values for

each successive 5% supplement of water are listed in Table C-9 for the four economic sectors. The percent changes

in yield from the present yield values in each sector are also listed in Table C-9 for water increments, and are


depicted in Figure C-14. Average percent change per 5% increase interval is given at the bottom of Table C-9, and

is highest for fisheries, followed by the agriculture, urban and tourist sectors.

Economic Analysis of Water Use

Figure C-15 depicts a diagram of the regional watershed basin, emphasizing water flows among the

subsystems. The macroeconomic values of water at different stages, from rainfall through surface and ground water

extraction to wastewater generation, are given in Table C-10. Macroeconomic value is calculated as the EMergy in a

cubic meter of water divided by the EMergy-to-dollar ratio of the economic region, and represents the amount of

the gross domestic product attributable to the water contribution. These values are compared to more typical

economic or marginal values for water, where such values were found in the literature.

From Table C-10 it can be seen that, as water is concentrated from rainfall through river flow to

groundwater, its macroeconomic value increases. Macroeconomic values were found to be lowest for the least

processed water sources such as rainfall, river inflow and fisheries, and greatest for the more concentrated sources

such as groundwater, irrigation water, municipal water and wastewater. In addition, the macroeconomic value of

each subsystem production process (referred to as pathway or interaction in Table C-10) is also given on a per cubic

meter basis for water supporting each subsystem. When water is extracted, processed and delivered for an economic

use such as agriculture or support of an urban population, its value increases. The more energy required in

delivering water to a sector, the higher its macroeconomic value. Macroeconomic value for subsystem interactions

on a per cubic meter basis is greatest for tourism, followed by the urban, agriculture and fisheries sectors.

Alternative Uses for Wastewater

Alternate uses for treated wastewater were evaluated including application to agricultural lands and

discharge to wetlands.

Agricultural land application. The amount of wastewater generated for each urban center in the basin was

calculated as 90% of the total water consumed. Values of wastewater generation are listed in Table C-11, along

with population and consumption for the urban areas in the basin. Total irrigation requirement was estimated as the

consumptive use of the crops divided by the irrigation system efficiency. Crop consumptive use was calculated using


the Blaney-Criddle method, and was found to be 0.78 m/yr. The efficiency of the irrigation system was estimated to

be 60% for ditch irrigation (FAO, 1979). Total irrigated land area required for recycle of the treated wastewater

was calculated as the total volume of wastewater divided by the irrigation requirements, in meters (cubic meters

required per square meter application area). Total irrigation requirement is then equal to 1.3 m/yr. Application

areas needed to satisfy the irrigation requirement for each urban area are given in Table C-11.


Regional Overview

The regional economy of the Banderas Bay Basin is driven primarily by the tourism industry and, to a

lesser extent, agriculture, fisheries and livestock production. As noted in Table C-2, 49% of all purchased inputs to

the region are for tourist services. However, part of the remaining 51% of purchased inputs goes towards urban

activities, which indirectly contribute to the tourism industry through supporting service industries such as restaurants

and rental and travel agencies. In addition, these purchased inputs also support the general population a large

percentage of which comprise the work force for the tourism industry and the related service industries.

Due to the lack of indigenous resources, such as fuels and construction materials, 84% of the EMergy input

to the system must be purchased from outside the region with half of these purchases going toward tourist services.

By comparison, only 26% of purchased EMergy inputs estimated for Mexico were from outside sources. The

remaining 16% of EMergy inputs to the basin is derived from renewable resources such as rain and river inputs.

The high EMergy-to-dollar ratio (1.07 E+13) was greater than that for both Mexico and the world average, which

may result from the inability to accurately assess the large amounts of resources available in relation to dollars

circulating in the economy. However, a large percentage of EMergy in the area is imported from outside the system

to support tourism while money received from tourism circulates back to purchase these imports. Similarly, EMergy

per capital and EMergy per unit area are also greater than those for Mexico, also due to the large amounts of

EMergy in purchased inputs for tourism.


On the regional scale, net imports to the area are slightly higher than net exports. However, net imports

for tourism are lower than net exports in tourist service. A higher imports to exports ratio for the region is probably

due to fewer purchased imports required for cash crops, fisheries, and livestock production relative to indigenous

inputs supporting these systems. The investment ratio of EMergy bought from the economy to EMergy coming from

the environment without payment is 5.36, approximately twice as large as that calculated for Mexico, suggesting

there is more dollar cost per unit EMergy input to the region relative to the country average. Similarly, the ratio of

purchased EMergy to the total yield of the economy in the basin (1.19) is lower than the average for Mexico (3.85),

suggesting the region is relying less on natural inputs to support its production processes and more on purchased

inputs, on average, than is the country as a whole.

Evaluation of Water Supply Systems for Economic Sectors

An evaluation of water's contribution to an economy begins with an analysis of the systems used to extract,

process and deliver the water as a commodity to interact in the production activities of the economic sectors. The

first eight indices of Table C-8 describe the EMergy flows contributing to the water systems for each sector, and the

amount of economic interaction required to support these systems. A comparison of transformities for water in

Table C-8, line 4, shows that the urban and tourist sectors required large amounts of energy investment for

provisions of water. Transformities for municipal water are five times larger than irrigation water and four times

larger than fisheries water. Such high transformities reflect the large amounts of fuels, goods and services required

to retrieve, process and transport water from its source to the urban centers while providing for suitable water


Production subsystems such as agriculture and fisheries rely more on natural resource inputs and less on

purchased inputs for delivery of water supplies. In fact, all water required for fishery production is received "free of

charge" from the environment. This is further illustrated by the fact that 77% of total inputs for municipal water are

purchased, while only 8% are purchased for agricultural water. The water yield ratios for each sector's water system

shows how much yield is supported by purchased inputs for the water system, where higher yield ratios reflect a

system that effectively matches fewer purchased inputs with renewable inputs to produce a higher quality water

commodity. Although not listed in line 8, fisheries water would actually have the highest EMergy yield ratio, since


no purchased inputs are needed to process the water. The yield ratio for irrigation water is approximately ten times

larger than that for municipal water, because fewer purchased inputs are needed to deliver irrigation water relative

to the large amounts of imports required for processing municipal water. This is also evident in the investment ratio

for water systems in which three units of purchased inputs are required for each unit of renewable input for

production of municipal water, while ten units of renewable EMergy is matched with one unit of purchased input for

agricultural water production.

Comparing water delivery systems for the sectors shows fisheries and agricultural water supply systems are

more efficient and support more water yield per amount of purchased inputs than municipal water. Another way of

evaluating the contribution of water to the economy is related to the degree to which delivered water supports

production processes in each sector of the economy.

Contribution of Water to the Economy

Items 9 through 17 in Table C-8 describe EMergy flows supporting production and economic processes

within each sector, emphasizing EMergy contributions from delivered water. Values of purchased inputs other than

water imports are given for each subsystem in Table C-8, line 9. Total imported EMergy is highest for tourist

industry followed by the urban sector and least for agriculture and fisheries. The fraction of total EMergy that is

purchased is 98% and 99% for urban and tourist sectors, respectively. This is not surprising, since both these sectors

are predominantly dependent on imports. The agricultural sector imports 50% of its total EMergy while fisheries

has only 2% of its total EMergy from purchased inputs.

A comparison of investment ratios (purchased/free EMergy inputs) for the sectors shows that agriculture

and fisheries sectors have much lower ratios than that calculated for the regional economy (5.36, Table C-2, line 17),

while urban and tourist sectors are nine and thirty-six times larger than the regional value, respectively. This would

suggest that the agriculture and fisheries subsystems have more to sell and less to buy, and are therefore more

competitive than the other sectors that are 98-99% dependent on purchased inputs.

The EMergy yield ratio is highest for fisheries and much larger than the ratio calculated for the regional

system of 1.2 (Table C-2, line 16). The yield ratio for agriculture (2.01) is much less than fisheries, although still

larger than the regional value. Urban and tourist sectors each have ratios just greater than 1 and, subsequently, less


than the regional ratio. Higher EMergy yield ratios for fisheries and agriculture suggest more abundant renewable

sources supplying the system and, therefore, more activities can be supported by these systems. The much lower

ratios for urban and tourist sectors suggest that sources are no longer available for continued growth, and perhaps

further development of these industries should be curtailed.

The relevance of water to each subsystem production process is reflected in the percent of total EMergy

input attributable to water delivery and consumption, with fisheries having the highest influence of water (99.4%),

followed by agriculture (54.3%), urban (9.04%), and tourist uses (2.37%) (Table C-8, line 13). These numbers

would suggest that, although water is certainly a necessity in all of the sectors, its ability to contribute to economic

growth in each of the production processes is most limited for urban and tourist sectors but may have significant

effects in the agricultural and fisheries sectors.

The marginal macroeconomic value of water in its raw and processed states reveals to what extent the

water source or commodity supports production in the subsystem. Tourism has the highest EMergy yield per

EMergy input of raw water (181.7), followed by the urban, agriculture and fisheries sectors. The same trend is true

for processed water; however, yield supported decreases by one fourth for the tourist and urban sectors, while yield

decreases only marginally for the agricultural sector. This would suggest that water contributes more to the regional

economy by supporting greater yields from the urban and tourist sectors. However, considering that the tourist and

urban sectors have maximized their development potential, as is suggested by the very low EMergy yield ratios for

each, it is not conceivable that supplying additional water to these sectors will support a significant yield.

Furthermore, since the percent of total EMergy input from water is very low for both sectors compared to the large

amounts of purchased inputs, increases in delivered water may not support much greater yields from either the

tourist or urban sectors.

Table C-9 shows subsystem yield values for increments of 5% increases in the amount of water delivered to

each sector. The tourist sector shows a 0.15% change in production for the increase in water supply delivered, while

the urban sector is slightly larger, with a 0.45% increase. Compared to 2.38% and 4.59% increases in agriculture

and fisheries production for each additional 5% water increase, respectively, the urban and tourist sectors do not

appear to support much more yield per water input, even though the overall yield for these sectors is still greater

than for either agriculture or fisheries. Supplying additional water to the urban and tourist sectors at their current

state of development would not be a wise investment of EMergy, since these sectors will not be able to produce


significant changes in yield for the EMergy in water invested. Additional water can support greater production in

the agriculture and fisheries sectors, since these sectors efficiently match fewer purchased inputs with the available

renewable EMergy in the water.

The amount of water supplying urban and tourist systems should not be reduced, however, since this is

necessary to maintain the present yield from the system, and any decrease in water EMergy inputs would cause a

further decrease in yield. If further development occurs in either the urban or tourist sectors, increased water would

be needed, with an EMergy value matching the existing system. For systems that have not reached their

development potential, water should be given priority over those that have a high marginal macroeconomic value of

water, a greater percent of their total EMergy attributable to water, and an EMergy yield ratio equal to or greater

than the larger system in which the subsystem operates.

Wastewater from the urban areas and tourist developments is typically discharged either to the river or

directly into the ocean. The transformities of raw and treated wastewater are greater than that for river flow, and

may contribute a large amount of EMergy to the bay system in addition to the river water. The transformity of

wastewater is also greater than that calculated for irrigation water. Using the high quality, nutrient rich treated

wastewater for irrigation purposes would contribute more EMergy to the economy through crop production than

would be received from using diverted river water or pumped ground water. In other words, the agricultural system

would receive a higher quality water source by utilizing treated effluent, than it would by continuing with the existing

system of diverting water from surface and ground water sources. However, the costs of transporting the treated

effluent from the urban areas to the agricultural regions should be taken into account. Transporting wastewater

across longer distances will result in greater costs, resulting in a lower EMergy yield per purchased input for the

treated water. Considering that treated wastewater is generally discharged into the Ameca River, which in turn

contributes to 80% of total irrigation water, utilizing recycled wastewater may be most beneficial in close proximity

to the urban areas (to reduce transport costs), or as an alternative to groundwater sources (which require greater

purchased inputs for retrieval).


Comparative Values of Water Use

The macroeconomic value of water increases as water is concentrated from rainfall through surface water,

groundwater and ultimately to the final consumer use (Table C-10). When water is concentrated, its volume

decreases as the value added for processing and delivering increases. Therefore, the more energy used to extract,

treat and deliver water the greater its EMergy content. Comparing macroeconomic values shown in Table C-10 with

marginal values calculated for similar processes reveals that traditional economics usually undervalues the

contribution of water to the economy. Water contributes net EMergy to the economy when its EMergy value

exceeds the costs of obtaining it. As more inputs are purchased from outside the system to deliver water, its net

EMergy contribution to the system decreases.

Net EMergy contributions of water to agriculture and fisheries are higher than net EMergy contributions to

the municipal system. The economy can receive up to ten times the value for irrigation water than it pays in

processing costs. Similarly, fisheries water contributes up to nine times the value to the economy than is paid in

costs. The overall contribution of the water to the economy is measured by the agricultural, fisheries, urban and

tourist production supported by water inputs. The macroeconomic values for each sector interaction given in Table

C-10 show that tourism contributes more dollars to the GDP per cubic meter of water consumed than the other

sectors. The urban sector contributes fewer dollars to the economy per cubic meter compared to tourism, although

still much greater than dollars contributed from agriculture and fisheries. While these yield ratios suggest that

tourism and urban development have high returns, the increase in yield received per increase in water supplied is

much smaller for urban and tourist sectors compared to agricultural and fisheries sectors. Consequently, the

increase in the number of dollars contributed to the economy as a result of additional water supplied to the tourist

or urban sectors is smaller than that contributed by incremental yields from agriculture and fisheries production.

Alternative Uses for Wastewater

Application areas needed to satisfy the irrigation requirement for each urban area are given in Table C-11.

The larger and more populated urban areas in Jalisco (south of the Ameca River) can provide greater quantities of

recycled wastewater for irrigation, thereby supporting greater irrigated areas than the more limited urban centers in


Nayarit. Lands located at a greater distance from the Ameca River, or those whose groundwater sources are used

for irrigation, would benefit the most by utilizing recycled wastewaters. Lands located near the river would also

benefit from using treated effluent, since they would receive higher quality water than would be received from the

river source. Two treatment plants are located in the area, one in Puerta Vallarta serving Pitillal and Puerta

Vallarta, and the second outside the town of Las Juntas serving Ixtapa and Las Juntas. The costs associated with

irrigation uses of effluent from several of the larger towns in the basin are given in Table C-11. Costs were

estimated as the total EMergy in electricity, goods and services required to deliver the recycled water to the crop

land. The total irrigated area using wastewater was calculated to be 1.72 E+08 m2, or about 30% irrigated land in

the basin.

Summary and Conclusion

The contribution of water to an economy is a factor of the intrinsic value of the water itself, the efficiency

in producing and delivering the water commodity, the extent to which the economy is supported by the water, and

the efficiency of the economy itself. High quality water from more concentrated sources such as groundwater,

combined with large amounts of purchased inputs, is generally used to support higher yielding systems such as

tourism or urban sectors. Lower quality water from river sources, combined with fewer purchased inputs, supports

lower yielding subsystems such as agriculture and fisheries.

How water inputs influences each sector of an economy depends on the degree to which the sector is

dependent on the water input. Less industrialized production systems such as agriculture and fisheries require

greater inputs from water sources relative to purchased inputs, while urban and tourist sectors rely less on water

inputs and more on purchased imports. Larger increases in production yield will result from water increases, in

cases where water is a greater contributor to the production process. Water will also have a greater effect on

production for those systems that have not reached or surpassed their development potential. Increased availability

of any natural input to a system will not have an appreciable effect on an economy that is predominantly dependent

on purchased inputs from outside the system. Considering alternate water sources such as treated wastewater can

provide sectors such as agriculture and fisheries with higher quality water for less cost in extraction and delivery.


Ba y Ameca River


Punta "'
Miemaloya .

Figure C-1. Location Map of the Banderas Bay watershed basin. Black areas are urban,
crosshatched areas are agriculture, and stippled areas are forested.

Figure C-2. Energy systems diagram of Banderas Bay watershed basin showing the interplay of
renewable, nonrenewable, and purchased energies that drive the regional economy.

I I I-"--- --- $8.55
Renewable R Rural 5,24 N-
re3ourcsa system

E20 solar emiouleslyr T E8 S/yr


28..1 Imoort

ladiqeyus 33.3
sources 5.24 Banderas Bay ort
R.N3.N1 Basin N2.3.?P E3


Figure C-3. Summary diagrams of the economy of Banderas Bay Basin in 1989. The top diagram
shows the flows of energy from renewable and nonrenewable sources and from purchased
resources that drive the economy. The circle of money within the central box is GDP. The bottom
diagram is a further simplification of the economy, showing the main driving energies and balance
of imports and exports.

_ _

Figure C-4. The flows of water supporting Banderas Basin economy. Numbers on pathways
refer to calculated values in Table 4.

Figure C-5. Energy systems diagram of agriculture showing the interaction of water with
renewable and purchased inputs.







E 18 sej/yr

Figure C-6. Summary diagram of EMergy flows in water and purchased inputs that support
agricultural production.


Figure C-7. Energy systems diagram of marine fisheries in the Bay of Banderas showing the
interaction of water with renewable and purchased inputs.






5.4 N") YIELD

El 8 see/yr

Figure C-8. Summary diagram of EMergy flows in water and purchased inputs that support the
marine fishery of Bay of Banderas.

1t-iI m 1-1l r t

Figure C-9. Energy systems diagram of the urban sector of Banderas Basin showing the
interaction of water with renewable and purchased inputs.

Figure C-10. Energy systems diagram of the tourism sector of Banderas Basin economy showing
the interaction of water with renewable and purchased inputs.





I 301.7
NPUTS 549.5

E18 sej/yr

Figure C-11. Summary diagram of EMergy flows in water and purchased inputs that support the
urban sector of Banderas Basin economy.






t> Ocr"

E 18 sej/yr

Figure C-12. Summary diagram of EMergy flows in water and purchased inputs that support the
tourism sector of Banderas Basin economy.






Figure C-13. Diagram illustrating the flows of EMergy supporting water use. Lettered pathways
are: rain or river input (W), purchased inputs to treat and deliver water (F), water yield (X),
purchased inputs to the economic sector (Z), and yield from the sector (Yield).

Agriculture Fisherles Urban Tourist

Economic Sector

Figure C-14. Marginal effects of water increases on net yield from agricultural, fisheries, urban
and tourism sectors.

Figure C-15. Energy systems diagram of the Banderas Bay Basin including the marine fishery
showing the interplay of water and purchased goods and services that yield economic products.
Numbered pathways refer to calculated values in Table 10.

Table C-1. EMergy evaluation of Banderas Bay Basin watershed, 1989.

Trans- Solar Macroeconomic
Note Item Raw Units formity EMergy Value
(sej/unit) (E16 sej) (E5 1984 US$)


Rain, chemical
Rain, geopotential
Wind, kinetic
River Geopotential
River, Chem Pot
Topsoil formation







Agriculture prod
Livestock prod
Fuelwood prod
Forest extraction






Top Soil, erosion
Potable Water
Agricultural water
Municipal water
Raw Wastewater
Treated Wastewater

5.68E+14 J
4.78E+10 J





Natural Gas
Plastics & Rubber
Mech.& Trans Eqp.












Table C-1. continued

Trans- Solar Macroeconomic
Note Item Raw Units formity EMergy Value
(sej/unit) (E16 sej) (E5 1984 US$)

11 Furnishings 4.23E+13 J 4.00E+06 16919.936
12 Liquor 2.45E+12 J 6.00E+04 14.684
13 Services, region 4.14E+06 $ 3.32E+12 1372.843
Services, tourism 8.14E+07 $ 3.32E+12 27022.020
14 Fertilizer 2.17E+10 g 3.45E+09 7486.500 311.94
15 Pesticides 9.63E+08 g 1.48E+10 1425.240 59.39
16 Tourist EMergy See item 36 for calculation 41534.699 1730.63



17 Cash Crops 5.34E+14 J 4.81E+05 25675.799 1069.83
18 Fishery Products 5.20E+12 J 2.00E+06 1039.872 43.33
19 Livestock 2.51E+13 J 2.00E+06 5021.593 209.23
20 Service in exports 4.14E+06 $ 3.32E+12 1372.843 57.20
21 Tourist service 5.96E+08 $ 3.32E+12 197737.298 8239.12



1 Solar Energy. Average sunlight over the basin taken as 1.64E+02
kcal/cm^2/yr (Odum, 1987). Area = 1.16E+09 m^2 (INEGI, 1989).

Energy(J) = (1.16E+09 m^2)*(1.64E+0) Cal/cm^2/y)*(E+04 cm^2/m^2)
*(1-0.30)*(4186 J/kcal)
= 5.99E+18 J/yr

2 Rain (Chemical Potential). Average rainfall over the basin taken as
1.42 m/yr and 0.64 m/yr over the bay (SEDUE, 1990).
Evapotranspiration rate estimated as 70 % of rainfall.

Energy (land) (J)= (1.16E+09 m^2)*(1.42 m)*(1000kg/m^3)*(4.94E+03J/kg)
= 5.57E+15 J

Energy (shlf) (J)= (area of shelf)(Rainfall)(Gibbs no.)
= 4.88E+13 J

Total energy (J) = 5.62E+15 J/yr

3 Rain (Geopotential Energy). Average elevation taken as 400 m
(INEGI, 1990) and runoff rate estimated as 20 %.

Energy(J)= (1.14E+09 m2)(1.42 m)*(1000 kg/m3)*(400 m)*(9.8m/s2)
= 1.26E+15 J/yr

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