ANALYZING LAND USE EFFECTS ON RECHARGE THROUGH PLAYAS TO THE HIGH PLAINS AQUIFER IN WESTERN KANSAS

Intense pumping of the High Plains aquifer (HPA) for irrigation is leading to aquifer depletion in western Kansas. Playas are ecologically important, intermittent wetlands where recharge is 10-100 times greater than the surrounding land, but the controls on groundwater recharge rates from playas are poorly understood. 80% of playas in western Kansas are farmed compromising sediment structure and increasing sedimentation, which likely reduces groundwater recharge and ecological function within playas. The objective of this research is to quantify recharge rates in playas ranging in land use and size. The playas selected for the research vary in impairment and include fully restored playas with natural playa function, playas used as rangeland, grassland enrolled in the Conservation Reserve Program (CRP), dry cropland, and irrigated cropland. Matrix and porewater chemical concentrations will help to quantify fluid flux and time of travel through the vadose zone. Recharge rates will then be compared across different land uses. Water table piezometers will be installed in a subset of playas to confirm recharge rates by monitoring water level changes and measuring tritium and dissolved gases. The results will be used to determine the characteristics of playas most critical to recharging the HPA in an effort to extend the lifespan of the HPA. Adding to the number and diversity of playas studied and quantifying recharge rates through playas of different land uses in the Central High Plains will aid in better management of playas including farming practices to prevent further aquifer depletion.