ECOHYDROLOGY OF SEMIARID WOODLANDS AND RECHARGE OF THE EDWARDS AQUIFER

Extensive areas of semiarid grasslands and savannas have been converted into shrublands or woodlands, a process known as woody plant encroachment. The ecological and hydrological implications of these changes are not well understood but are important, especially in areas owhere most of the water and groundwater recharge are derived from these shrublands. One such region is the Edwards Plateau in the Texas Hill country, where juniper coverage is extensive and the hillslopes are composed of highly permeable, fractured limestone. In this area, the Edwards Aquifer Authority is currently advocating brush control to improve water yield. At the Honey Creek Experimental Watershed, we applied large plot (15m length) rainfall simlations above tree canopies to examine water fluxes and recharge for different rainfall regimes. We also used caves and natural precipitation to study water uptake through the fractured limestone. Considerable water uptake occurs between 5 and 20 m depth.