The effects of vegetation on the water balance of an Edwards Plateau watershed : a GIS modeling approach /
Shrub encroachment can reduce water yield from the
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Summary: | Shrub encroachment can reduce water yield from the rangelands of the Edwards Plateau region of Texas through increased evapotranspirational losses. This has been demonstrated through a number of small-scale empirical studies on the effect of vegetation on hydrology. The goal of this study was to investigate the effect of vegetation and brush management on the water balance at the landscape- scale on the Edwards Plateau using a GIS simulation modeling approach. A comprehensive GIS data base was developed for the 206 k study area, Cusenbary Draw watershed on the Edwards Plateau, as a foundation for assessing the effect of vegetation on water yield. Vegetation analysis was conducted for the study area using 1955 and 1990 aerial photography, digital image processing and GIS analysis. The overall woody vegetation cover remained relatively constant between 1955 and 1990 due to brush management practices adopted by ranches within the watershed. Range sites with the highest potential herbaceous production experienced declines in woody vegetation cover from 1955 to 1990. Conversely, incremental increases in woody vegetation cover were observed on range sites as herbaceous production potential declined. These observed differences in woody cover change between range sites imply a concentration of investment in brush management within range sites promising the highest rate of return. Simulation studies using the SPUR-91 hydrologic model were conducted to systematically evaluate the effect of vegetation cover and composition on the water balance of the watershed. Results of the simulation studies revealed the dynamics of landscape-scale hydrologic balances as a function of woody vegetation cover across range sites. The simulation results agreed well with the findings of similar small-scale and empirical studies. The simulation studies also revealed limitations of the SPLJR-91 hydrologic 'c model and suggested ways to improve the model structure. The results of the 91 simulation studies were used to assess the hydrologic impacts associated with two brush management scenarios. In the absence of brush management a 50% reduction in water yield from 1990 levels was predicted. However, with the implementation of a publicly funded brush management program a 180% increase over 1990 levels was predicted. |
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| Item Description: | Vita. "Major subject: Rangeland Ecology and Management". |
| Physical Description: | xi, 82 leaves : illustrations ; 28 cm. Issued also on microfiche from Lange Micrographics. |
| Bibliography: | Includes bibliographical references: pages 66-71. |