Soil and topographic controls on runoff generation from stepped landforms in the Edwards Plateau of Central Texas

The rugged Hill Country of Central Texas is part of the extensive Edwards Plateau region. Significant portions of the Texas Hill Country overlie the Glen Rose Tormation, which is characterized by a stair-step topography formed by the weathering of interbedded carbonate materials having different weathering susceptibilities. This process has sculpted the strata into a series of "risers" and "treads" that mimic stairways. In this paper, we document the soil hydrology within the riser-tread catena. Our results are counterintuitive in that we find the highest infiltration and deepest soils on the steep riser slopes. In addition, we find that the riser subsoils are saturated or very wet for extended periods. On the basis of these findings, we suggest that (1) groundwater recharge on these hillslopes is minimal and occurs only in highly fractured zones; (2) the water-holding capacity of the subsoils is sufficient for supporting the woody vegetation; and (3) runoff generation occurs as a combination of surface and subsurface flow, with the risers serving as sinks or recharge zones and the treads as source areas. Copyright 2007 by the American Geophysical Union.

Soil and topographic controls on runoff generation from stepped landforms in the Edwards Plateau of Central Texas Academic Article