Title: Water Resources Analysis Using Electronic Spreadsheets, Table 6: Summary of Simulation of Cypress Creek Above San Antonio: 1979
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Permanent Link: http://ufdc.ufl.edu/WL00000699/00001
 Material Information
Title: Water Resources Analysis Using Electronic Spreadsheets, Table 6: Summary of Simulation of Cypress Creek Above San Antonio: 1979
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Language: English
 Subjects
Spatial Coverage: North America -- United States of America -- Florida
 Notes
Abstract: Water Resources Analysis Using Electronic Spreadsheets, Table 6: Summary of Simulation of Cypress Creek Above San Antonio: 1979
General Note: Box 7, Folder 1 ( Vail Conference 1987 - 1987 ), Item 92
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00000699
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text










Table 6. Summary of Lotus Simulation of Cypress Creek
Above San Antonio: 1979.


A B C D E F G H I J K


Precipitation
Cypress Saint Weighted
Creek Leo Mean Evap
inches inches inches inches in
TOTAL 61.06 66.89 63.975 60.07
MEAN
MAX
MIN
STANDARD DEVIATION
KEY ASSUMPTIONS:
1.E-T=(ETMAX-ETRATE*(GRDEL-WTEL)) E


Cale
E-T Streamflow
ches cfs inches
45.1 10051 7.87
0.12 27.54
0.42 205.7
0 0
3.07 44.51

GRDEL
ETMAX
ETRATE


2.DRAINAGE AREA, SQUARE MILES =
3.STORAGE COEF. =
4.DISCHARGE-HEAD RELATIONSHIP = K*H^B

5.ELEVATION FOR WHICH BASE FLOW = 0, FEET
6.LEAKANCE, IN/AR
7.WEIGHTS OF RAIN GAGES CYPRESS CRK
ST LEO


CONTINUITY CHECK: dS/dT = (P-ET-Q-L)


dS/dT=


CALC
MEAS


63.975 IN.
45.169 IN.
7.886 IN.
8.200 IN.


2.719 IN.
2.611 IN.


PERCENT CONTRIBUTIONS

INFLOWS

P= 100%

OUTFLOWS

ET= 73.74%
Q= 12.87%
L= 13.39%


25

$'5- 026


Meas
Flow
cfs
10140
27.78
500
0
58.47


Meas
Head
inches

68.48
72.71
65.64
1.77


Cale
Head
inches

68.39
74.89
62.01
2.84

74
1
0.04
47.4
0.085
3.3
2
67
8.2
0.5
0.5










located approximately 60 miles from the study area. In HSPF, the

mean monthly evaporation was used. Evapotranspiration is

estimated as a function of evaporation and water table elevation,

i.e.,

ET = (ETmax-n*(Hgrd-Hwt))*E .................... (13)

where ET = evapotranspiration, inches of water, ETmax = maximum

ET rate, inches per day, n = reduction in ET rate per unit

decrease in head, Hgrd = ground elevation, feet, Hwt = water

table elevation, feet, and E = pan evaporation rate, inches per

day. ETmax, n, and Hgrd are used as calibration parameters.

The discharge in Cypress Creek is approximated by fitting a

power function of the form:

Q = a*Hb ......................................... (14)

where Q = estimated flow in cfs, H = estimated water table eleva-

tion at well 4, feet, and a,b = parameters. The calculated flow

in cfs is converted to inches/day over the catchment. Pumpage is

represented as a change in leakance. The model was calibrated

with water level data from well 4, located just north of the

Cypress Creek Wellfield.

The model estimates the daily flow and stage for the year.

The power of the spreadsheet approach is apparent during the

calibration. The key assumptions and calibration parameters are

shown at the bottom of the table. All of the equations in the

table are expressed in terms of the calibration parameters.

Thus, the new result is calculated immediately once the revised
parameter estimates are inserted. The final estimates are shown


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in the table. All of these values fall within the expected

range. The most sensitive assumption is the weighting on the

rain gages.

The results are quite good. The estimated mean flow of 27.5

cfs agrees closely with the measured flow of 27.8 cfs.

Similarly, the estimated mean stage of 68.4 feet is very close to

the measured stage of 68.5 feet, and the continuity check is very

good. The simulated vs. measured flows and stages are shown in

Figures 4 and 5 respectively. The fit is very good. The most

important loss term is ET. It is over three times as large as

the runoff, the next largest item in the water budget. The model

was calibrated to fit well for the normal range of flows. Thus,

simulated high flows may differ significantly from the measured

high flows.

This model is able to track the movement of the water table

below the streambed; this was a limitation of HSPF. Of course,

this model can be criticized for not explicitly tracking some

parts of the hydrologic cycle. The potentiometric head is not

analyzed. However, the analysis of the well data indicated

clearly that the potentiometric head is highly correlated with

the water table. Also, the unsaturated zone is not analyzed

explicitly. However, since no good information about the

relationship between the unsaturated zone and runoff and ET

exists, its effect can be included in the other terms of the

water budget.
Overall, the results for both the flows and heads at San


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