Riverwash

174-Riverwash. These miscellaneous areas are in active stream channels, on flood plains, and adjacent to drainageways. Slope is 0 to 5 percent. Elevation is 200 to 1,500 feet. The areas are inundated during periods of waterflow and are subject to constant deposition and removal of material. Vegetation consists of occasional willows, water grasses, and some brush.

Riverwash consists of erratically stratified layers of water-deposited sand, gravel, stones, and cobbles. Layers of sandy loam and silt loam are deposited for short periods but are subject to intermittent scouring and removal. Thickness of the strata ranges from 2 to 30 inches. Reaction is neutral or mildly alkaline. The organic matter content varies from stratum to stratum but is commonly low.

Included with Riverwash in mapping were small areas of Cortina soils.

Runoff is slow. The hazard of erosion is slight to very severe, depending on water velocity.

Riverwash is used as a source of sand and gravel. It is almost devoid of vegetation and has no agricultural use. Capability unit VIIIw-1 (14).