Wednesday, November 15, 2006

Surface and Subsurface Flow Relationships for Ogallala Aquifer Recharge.

Annesly Netthisinghe1, Wayne Hudnall1, Ken Rainwater1, Loren Smith1, Richard Zartman1, and Dennis Gitz2. (1) Texas Tech Univ, Plant and Soil Science Dept, MS 42122, Lubbock, TX 79409, (2) USDA-ARS, 3810 Fourth St, Lubbock, TX 79415-3397

The High Plains aquifer is a preeminently important natural groundwater resource for the United States.  This aquifer, as are many others in the U.S. and the world, are being mined with concomitant potential loss of agricultural productivity and human population.  This research seeks to evaluate the influences of current and past agricultural practices on the recharge potential of the High Plains aquifer.  Within the High Plains region of the Southern Great Plains there are 20,000 to 30,000 depressional wetlands known as playas.  It is hypothesized that these playas or the annulus surrounding them are areas of focused recharge for this aquifer.  We propose to estimate the water inflow to playas and determine surface location of subsequent aquifer recharge in three regions of soil textures (fine, medium and coarse) throughout the Southern High Plains.  In addition, most playas now have cultivated watersheds and have received large amounts of sediments from erosion.  This erosion has not occurred into the remaining relatively few playas that have native grassland watersheds.  Playas that have received large sediment loads have shorter hydroperiods than those with native grassland watersheds.  These altered hydroperiods are hypothesized to be result of (1) the playa wetland water being spread out over a larger area, subjecting it to greater evaporation and/or (2) changes in the infiltration characteristics of sediment now present in playa wetland. Therefore, playas in each of these outer basin soil areas with and without anthropogenic sediments will be monitored and compared for recharge of water focused within or around these basins.  Understanding the recharge phenomenon will not only answer basic scientific questions relating to High Plains aquifer recharge, but also give insight into management and conservation decisions to be implemented in the future.