The impact of stream channelization on the geomorphic stability of an arid-region river

Little is known about how stream channelization affects the stability of dryland rivers. This study investigates the impact of channelization on the morphology, energy conditions, and sediment-transport potential of a 14.8km reach of Santa Rosa Wash - an ephemeral stream in south-central Arizona. Historical evidence and field data indicate that the morphology of the wash before channelization consisted of numerous anabranched channels set within a broad floodplain. This form differed substantially from the trapezoidal morphology of the flood-control channel that replaced the wash. Immediately following construction in the early 1960s, the modified channel became unstable and began to enlarge and degrade. In 1983 a large headcut formed in the channel during a major flood; this feature apparently migrates upstream episodically in response to large flows. -from Author