UNDERSTANDING AND INTERPRETING BRAZOS RIVER ALLUVIUM AQUIFER WATER TABLE FLUCTUATIONS TO BETTER MANAGE WATER RESOURCES IN MCLENNAN COUNTY, TEXAS---A CASE STUDY

The Brazos River Alluvium Aquifer (BRAA) is a shallow, unconfined aquifer in McLennan County, Texas. This research studies how and why the water level fluctuates in this unconfined aquifer. Water level information in any aquifer is important to the understanding of the water resource hence the purpose of this research. Major factors that affect the water table include rainfall, evapotranspiration, and pumping. Some other possible stressors include changes in the Brazos River water level, barometric pressure, and Earth tides. The main source of data for this project was obtained from water level data loggers installed in BRAA piezometers. The data loggers record water levels hourly, and data patterns are examined over a range of time intervals from diel fluctuations to seasonal trends. In addition to existing data that only included water levels, data loggers that also measure temperature and specific conductance were installed to better evaluate rain event impacts. Tipping bucket rain gauges at the research property and others placed around McLennan County provided records for precipitation near the piezometers with water-level data loggers and in the region. Barometric pressure was recorded within one of the piezometers containing a water-level data logger. The Brazos River water level was obtained from the USGS stream gage located near the research site at Loop 340 in Waco. Finally, the possible impacts of pumping groundwater from the BRAA were investigated. The results will help groundwater managers understand water-level response patterns related to different aquifer stresses and help them make informed management decisions.