Vegetation and soils A. Sparse shrub cover means soil surface is exposed to rain splash. This compacts surface pore space and inhibits infiltration. Thus, surface runoff after heavy rains can be substantial and rapid. B. Results in erosive loss of fine textured sediments at surface, leaving behind a characteristic gravelly surface, called a desert pavement . Drainage networks in arid landscapes A. Generally low discharges.
Streams are intermittent in nature.
Most of the time, channels are dry. When it does rain, lack of vegetation cover combines with desert pavement to produce rapid overland flow and flash flooding in normally dry stream channels. This rapid delivery of overland flow to stream channels produces a burst of elevated discharge, which temporarily increases stream capacity relative to sediment load. The result is downcutting of small canyons, called washes or arroyos . Basin and Range Topography A. Alternating uplifted and down-dropped normal fault blocks can produce a landscape of mountain ranges separated by broad basins.