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Simulation of Streamflow and Estimation of Recharge to the Edwards Aquifer in the Hondo Creek, Verde Creek, and San Geronimo Creek Watersheds, South-Central Texas, 1951–2003

By Darwin J. Ockerman

U.S. Geological Survey
Scientific Investigations Report 2005–5252

ONLINE ONLY

In cooperation with the San Antonio Water System


Abstract

The U.S. Geological Survey, in cooperation with the San Antonio Water System, constructed three watershed models using the Hydrological Simulation Program—FORTRAN (HSPF) to simulate streamflow and estimate recharge to the Edwards aquifer in the Hondo Creek, Verde Creek, and San Geronimo Creek watersheds in south-central Texas. The three models were calibrated and tested with available data collected during 1992–2003. Simulations of streamflow and recharge were done for 1951–2003. The approach to construct the models was to first calibrate the Hondo Creek model (with an hourly time step) using 1992–99 data and test the model using 2000–2003 data. The Hondo Creek model parameters then were applied to the Verde Creek and San Geronimo Creek watersheds to construct the Verde Creek and San Geronimo Creek models. The simulated streamflows for Hondo Creek are considered acceptable. Annual, monthly, and daily simulated streamflows adequately match measured values, but simulated hourly streamflows do not. The accuracy of streamflow simulations for Verde Creek is uncertain. For San Geronimo Creek, the match of measured and simulated annual and monthly streamflows is acceptable (or nearly so); but for daily and hourly streamflows, the calibration is relatively poor. Simulated average annual total streamflow for 1951–2003 to Hondo Creek, Verde Creek, and San Geronimo Creek is 45,400; 32,400; and 11,100 acre-feet, respectively. Simulated average annual streamflow at the respective watershed outlets is 13,000; 16,200; and 6,920 acre-feet. The difference between total streamflow and streamflow at the watershed outlet is streamflow lost to channel infiltration. Estimated average annual Edwards aquifer recharge for Hondo Creek, Verde Creek, and San Geronimo Creek watersheds for 1951–2003 is 37,900 acre-feet (5.04 inches), 26,000 acre-feet (3.36 inches), and 5,940 acre-feet (1.97 inches), respectively. Most of the recharge (about 77 percent for the three watersheds together) occurs as streamflow channel infiltration. Diffuse recharge (direct infiltration of rainfall to the aquifer) accounts for the remaining 23 percent of recharge. For the Hondo Creek watershed, the HSPF recharge estimates for 1992–2003 averaged about 22 percent less than those estimated by the Puente method, a method the U.S. Geological Survey has used to compute annual recharge to the Edwards aquifer since 1978. HSPF recharge estimates for the Verde Creek watershed average about 40 percent less than those estimated by the Puente method.

Table of Contents

Abstract

Introduction

Purpose and Scope

Description of Study-Area Watersheds

Simulation Approach

Simulation of Streamflow and Estimation of Recharge

Data Collection and Compilation

Model Construction

Model Calibration and Testing

Streamflow

Hondo Creek Model

Verde Creek Model

San Geronimo Creek Model

Evapotranspiration

Summary of HSPF Process-Related Parameters

Streamflow, 1951–2003

Recharge, 1951–2003

Model Limitations and Assessment

Summary

References

Figures

1–2.   Maps showing:
  1.   Location of Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas
  2.   Land cover in Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas, early to mid-1990s
3.   Diagram showing Hydrological Simulation Program—FORTRAN (HSPF) flowchart for (a) impervious and (b) pervious land segments
4–6.   Maps showing:
  4.   Location of data-collection sites used for Hydrological Simulation Program—FORTRAN (HSPF) model calibration, testing, and simulations, Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas
  5.   Subwatersheds in Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas, for Hydrological Simulation Program—FORTRAN (HSPF) model development
  6.   Primary rain gages and associated rainfall areas for Hydrological Simulation Program—FORTRAN (HSPF) model calibration, testing, and simulations, Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas
7–9.   Graphs showing:
  7.   Measured and simulated daily mean streamflow at U.S. Geological Survey streamflow-gaging station 08200000 Hondo Creek near Tarpley, Texas, 1992–2003
  8.   Measured and simulated daily mean streamflow at U.S. Geological Survey streamflow-gaging station 08200700 Hondo Creek at King Waterhole near Hondo, Texas, 1992–2003
  9.   Measured and simulated daily mean streamflow at U.S. Geological Survey streamflow-gaging station 08180590 San Geronimo Creek Reservoir inflow near Rio Medina, Texas, 1992–93

Tables

1.   Process-related model parameters for the Hydrological Simulation Program—FORTRAN
2.   Basin-related model parameters for the Hydrological Simulation Program—FORTRAN
3.   Data-collection stations used for Hydrological Simulation Program—FORTRAN model input, calibration, and simulations for Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas
4.   Sources of rainfall data used to provide missing record and time-step disaggregation for primary rainfall time series used in the Hydrologic Simulation Program—FORTRAN (HSPF) model, Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas
5.   Subwatershed drainage areas, Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas
6.   Streamflow calibration and testing results, Hydrological Simulation Program—FORTRAN model, Hondo Creek watershed, south-central Texas, 1992–2003
7.   Streamflow testing and recalibration results, Hydrological Simulation Program—FORTRAN model, San Geronimo Creek watershed, south-central Texas, 1992–93
8.   Rainfall and simulated evapotranspiration, Hydrological Simulation Program—FORTRAN model, Hondo Creek watershed, south-central Texas, 1992–2003
9.   Process-related annual parameters for pervious and impervious land segments, Hydrological Simulation Program—FORTRAN models, Hondo Creek and Verde Creek watersheds, south-central Texas
10.   Process-related annual parameters for pervious and impervious land segments, Hydrological Simulation Program—FORTRAN model, San Geronimo Creek watershed, south-central Texas
11.   Monthly values of lower-zone evapotranspiration (LZETP) parameter, Hydrological Simulation Program—FORTRAN models, Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas
12.   Simulated average annual streamflow volumes for Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas, 1951–2003
13.   Estimated annual rainfall and Edwards aquifer recharge, Hondo Creek, Verde Creek, and San Geronimo Creek watersheds, south-central Texas, 1951–2003
14.   Comparison of Edwards aquifer recharge estimates from Hydrological Simulation Program—FORTRAN (HSPF) with historical (Puente method) U.S. Geological Survey recharge estimates for Hondo Creek and Verde Creek watersheds, south-central Texas, 1992–2003

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