Erosion on Miniature Pediments in Badlands National Monument, South Dakota

Abstract

Measurements of erosion on miniature pediments in Badlands National Monument, South Dakota, show that during almost eight years, the pediments were lowered by sheetwash. The adjacent hillslopes have retreated leaving a belt of newly formed pediment from 6 to 12 cm wide at their bases. The hillslopes are rough and relatively permeable; the miniature pediments are smooth and less permeable. Calculations based on the Manning equation suggest that the velocity of overland flow on the pediments may be of the same magnitude as that on the hillslopes. The decrease in roughness from hillslope to pediment compensates for the decrease in slope angle. The pediments are swept free of debris and are regraded by a more effective utilization of runoff energy.