GIS AND GEOPHYSICAL ANALYSIS OF SEDIMENTATION IN FORT PHANTOM HILL RESERVOIR, WEST CENTRAL TEXAS, CORRELATED TO WATERSHED CHARACTERISTICS

Fort Phantom Hill Reservoir was impounded in 1937 and is located in Jones County, Texas. The original storage capacity was 9.12x107 cubic meters, and a surface area of 1718.3 square hectometers. The drainage area covers 1217.3 square kilometers, predominantly in Taylor County. The rates of sediment fluxes in lakes and reservoirs are a reflection of processes and characteristics of the watershed. The GIS analysis of the watershed showed the agricultural land use to be (cultivated fields 28%, pastures 23%) 51% of the watershed. Tree cover (mesquite trees 12% and other trees 22%) accounted for 33% of the land use, while urban use accounted for 9% of the area. All data will be used in the Universal Soil Loss Equation (USLE) model in order to determine the relationship between sediment fluxes and watershed characteristics. Bathymetry data will also be discussed. Plans are underway to remove mesquite (Prosopis glandulosa) from the watershed in order to reduce water loss due to the high evapotranspiration, which will have a negative impact on the watershed sediment yields. Therefore, this study will provide the necessary baseline sediment flux information important for reservoir management as well as future environmental analysis.