MONITORING INFILTRATION AND RECHARGE OF PLAYA LAKES IN THE TEXAS SOUTHERN HIGH PLAINS

Preliminary results from playa lakes monitored by the Texas Water Development Board (TWDB) suggest that a small volume of deep infiltration and recharge to the Ogallala aquifer occurs along the margins of the lake beds, while the majority of infiltration associated with a typical inundation remains stored as soil moisture in near-surface clays beneath the central portion of the playa without contributing significantly to groundwater recharge. The TWDB is monitoring 30 playa lakes in the Southern High Plains to evaluate current groundwater recharge rates from the lakes and assess the potential for managed recharge from the lakes to extend the usable resources in the Ogallala. Following the extreme drought of 2011, over 20 separate inundation events have been observed in 2012. Discrete data from soil moisture sensors show limited vertical movement of soil moisture in the central area of most monitored playas. Larger scale soil resistivity imaging suggests that deep infiltration occurs primarily at the lake margins, with the infiltration front advancing as much as 20 meters within three months. Continued monitoring is planned to confirm preliminary results and support design of playa modifications to enhance recharge.