Geologic and hydrogeologic information for a geodatabase for the Brazos River Alluvium Aquifer, Bosque County to Fort Bend County, Texas

During July-October 2006, the U.S. Geological Survey (USGS), in cooperation with the Texas Water Development Board (TWDB), developed geologic and hydrogeologic information for a geodatabase for use in development of a Groundwater Availability Model (GAM) of the Brazos River alluvium aquifer along the Brazos River from Bosque County to Fort Bend County, Texas. The report provides geologic and hydrogeologic information for a study area that encompasses the Brazos River alluvium aquifer, a 1/2-mile-wide lateral buffer surrounding the aquifer, and the rocks immediately underlying the aquifer. The geodatabase involves use of a thematic approach to create layers of feature data using a geographic information system. Feature classes represent the various types of data that are keyed to spatial location and related to one another within the geodatabase. The 1/2-mile-wide buffer surrounding the aquifer was applied to include data from wells constructed primarily in alluvium but outside the boundary of the Brazos River alluvium aquifer. A 1/2- by 1/2-mile grid was generated on the study area to facilitate uniform distribution of data for eventual input into the GAM. Data were compiled primarily from drillers and borehole geophysical logs from government agencies and universities, hydrogeologic sections and maps from published reports, and agency files. The geodatabase contains 450 points with geologic data and 280 points with hydrogeologic data.