Lake Brownwood Watershed - Texas State Soil and Water ...

cover was separated by species (cedar, mesquite, oak, and mixed) and by density (heavy,
moderate, light). After calibration of SWAT to existing stream gauge and reservoir data, brush
removal was simulated by converting all heavy and moderate categories of brush (except oak)
to open range (native grass). Removal of light brush was not simulated.
Simulated changes in water yield resulting from brush treatment varied by subbasin, with all
subbasins showing increased water yield as a result of removing brush. Average annual water
yield increases ranged from about 111,000 gallons per treated acre in the Fort Phantom Hill
watershed to about 178,000 gallons per treated acre in the Palo Pinto watershed. Water yield
increases per treated acre were similar to a previous study (COE, 2002), but higher than TAES
(2000). As in previous studies, there was a strong, positive correlation between water yield
increase and precipitation.
For this study, we assumed removal of 100 percent of heavy and moderate categories of brush
(except oak). Actual amounts and locations of brush removed will be dependent on economics
and wildlife habitat considerations.
The hydrologic response of each watershed is directly dependent on receiving precipitation
events that provide the opportunity for surface runoff and ground water flow.
A1-10