Estimation of Recharge to the Middle Trinity Aquifer of Central Texas Using Water-Level Fluctuations

A 23-site monitoring well network located in the Trinity Aquifer region of Central Texas, with all wells penetrating the Middle Trinity Aquifer, was used with available values of aquifer storativity and specific yield to estimate recharge to the aquifer for 1999 and 2000. As part of the investigation, the Edwards Aquifer Research & Data Center (EARDC) staff worked with the Texas Water Development Board (TWDB) and local groundwater conservation districts to install five new recording well monitors in the study area, comprising about 4500 square miles. The results of the investigation yielded a method of recharge calculation different from the stream baseflow method now in use. The recharge values obtained by this study were substantially less than representative results obtained by the stream baseflow method, perhaps due to inadequately defined aquifer storativity and low precipitation throughout much of 1999 and 2000.