Spatial distribution and morphology of sediments on the Texas Southern High Plains, USA Playa Wetlands

Abstract

Playa wetlands are unique geomorphic features on the Southern High Plains of the United States and serve as major recharge sites for the Ogallala aquifer. This study was conducted to evaluate outerbasin cropping system influence on sedimentation within playas. Six playas, three cropland and three rangeland outerbasin watersheds, were selected for the research. Twenty-five soil core samples were collected from each playa using the spoke-wheel design. Samples were taken to Texas Tech University and processed for soil color and particle size distribution analysis. Watershed management was an important aspect influencing the degree of sedimentation in playa wetlands. Sediment depth patterns suggested uneven distribution across the playa basins. Watershed drainage networks and topographic characteristics may have influenced spatial distribution. Measured sediment depth did not vary between land uses, but the cropland playas accumulated more sediments (greater volume) than the playas surrounded by rangeland. Soil color evaluation proved to be an adequate parameter to distinguish historically deposited sediments from the pre-settler sediments. The surface sediment soil color was predominately 10YR 3/2 (very-dark, grayish brown) for the Briscoe and Swisher County playas and 10YR 3/1 (very-dark gray) for the Floyd County playas. Spatial distribution of sediments could be used to evaluate outerbasin management practices.