EVOLUTION OF A DISCONTINUOUS GULLY SYSTEM.

A discontinuous gully system which consists of a series of discrete basins has developed on an alluvial valley fill in northern Colorado. Field evidence suggests that shallow depressions develop, under the influence of overland flow, from initial breaks in thee vegetation cover. As a depression becomes too deep to allow water to lift material out, wind rakes on the role of removing particles from the basin and overland flow and slumping continue to extend it. Eventually successive basins coalesce, allowing water to flow throughout the system and once again become the predominant erosive agent. It appears that the gully system has developed under the influence of geomorphic agents which operate infrequently, during heavy rain or strong winds. These discontinuous gully systems are quite widespread, and have some impact on the rangeland economy. The development of incipient basins may be prevented by planting shrubs and grass, and well-developed basins may be stabilized by the use of water spreaders and planting. [ABSTRACT FROM AUTHOR]