Relationship Between Landscape Aspect and Playa Alignment on the Texas High Plains

Abstract

Playas (ephemeral lakes) of the Texas High Plains (THP) appear to be aligned when observed on small scale maps or aerial photographs. Playa orientation, however, has eluded spatial description and the landscape topography relationships are unknown. This study examined the relationship between landscape aspect and playa alignment for 23 THP counties.  Landscape topography was evaluated using aspect direction as determined from 100 ft (~33m) contours presented on U. S. Geological Survey 1:250,000 topographic quadrangle maps.  Playa alignment was evaluated with the Hough transform using a Linear Evaluation of Actual Points Program (LEAPP).  Playa alignment from LEAPP correlated with landscape aspect from USGS map contours with a correlation coefficient of 0.17.  Playas were aligned with aspect direction by quadrant for 13 of the 23 THP counties evaluated.  For those 13 counties, the average aspect was 112 degrees for the contour method compared to 117 degrees for the LEAPP method indicating a relationship between landscape aspect and playa alignment.