SPATIAL WATER BALANCE OF TEXAS

By Seann M. Reed, David R. Maidment, and JŽr™me Patoux

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TABLE OF CONTENTS

	1. INTRODUCTION
	2. LITERATURE REVIEW

	2.1 Atmospheric Water Balance Studies
	2.2 Soil Water Balance Studies
	2.3 Surface Water Balance Studies

	2.3.1 Water Balances of Texas
	2.3.2 Runoff Mapping

3. ATMOSPHERIC WATER BALANCE

	3.1 Atmospheric Data
	3.2 Methodology

	3.2.1 Water Balance Equations
	3.2.2 A Control Volume over Texas
	3.2.3 Direct Computation and Flux Integration Approaches to Estimate Divergence

	3.2.3.1 Divergence approach
	3.2.3.2 Flux integration approach

3.3 Results and Discussion

4.1 Methodology

	4.1.1 Model Description
	4.1.2 Description of input data

	4.1.2.1 Climate data
	4.1.2.2 Water-holding capacity data
	4.1.2.3 Open Water Evaporation Estimates
	4.1.2.4 Radiation Data

4.1.3 Water-holding capacity of the soil

4.1.4 Estimating Actual Evapotranspiration

4.1.5 Budgeting soil moisture to yield surplus

4.1.6 Balancing Soil Moisture

4.2 Potential Evapotranspiration

	4.2.1 Potential evaporation vs. potential evapotranspiration
	4.2.2 Penman combination method
	4.2.3 Simpler Methods

	4.2.3.1 Pan coefficients
	4.2.3.2 Priestley-Taylor Method
	4.2.3.3 Comparison of Pan and Priestley-Taylor Methods

4.3 Results

4.4 Summary

	5.1 Overview
	5.2 Methodology

	5.2.1 Digital Elevation Model Processing
	5.2.2 Selecting Gaging Stations for Analysis
	5.2.3 Watershed Delineation
	5.2.4 Compiling Watershed Attributes

	5.2.4.1 Determining Mean Precipitation and Net Inflow
	5.2.4.2 Reservoir Evaporation
	5.2.4.3 Urban Land Use
	5.2.4.4 Recharge
	5.2.4.5 Springs

5.3 Results and Discussion

	5.3.1 Expected Runoff
	5.3.2 Mapping Actual Runoff and Evaporation
	5.3.3 Mapping the Bowen Ratio
	5.3.4 Summary Tables
	5.3.5 Summary and Discussion

6. CONCLUSIONS

7. ACKNOWLEDGEMENT

8. REFERENCES

9. APPENDIX