GEOMORPHOMETRY AND SPATIAL PATTERNS OF THE SOUTH TEXAS SAND SHEET

Morphometric analysis of a sand sheet on the Texas Coastal Plain is presented. Landscape-scale patterns reveal characteristic physical features of an aeolian landscape that signify episodes of its evolutionary sequence. Morphometric parameterizations of various physical characteristics are analyzed to elucidate the historical evolution and potential for future reactivation of the South Texas Sand Sheet. An airborne LiDAR-derived elevation model is used to generate parameters including slope, aspect, curvature, and roughness to classify the landscape according to surface characteristics. Moisture and vegetation indices are computed from Landsat Thematic Mapper data to include soil and biological conditions. These data reveal zones of stability and instability, as well as distinct degrees of instability that are thought to be related to age. Patterns of crestline orientation, height, and superimposition suggest pulses of sediment are delivered to the system at large scales, affecting its evolution and activation patterns. Areas of active sands have an anisotropic morphological structure aligned with the prevailing southeasterly winds. This directional signature is enhanced by the multiple trailing ridges that delineate paths of larger migrating pulses of sediment. Biophysical patterns of the South Texas Sand Sheet reveal unique spatial structures and scale dependencies, which enable classification of the landscape and sequential ordering of its history. Our results demonstrate that land surface parameters can be used to assess and characterize different states in the evolution of a coastal aeolian landscape.