High Flow Requirements for Channel and Habitat Maintenance on the Lower Duchesne River between Randlett and Ouray, Utah

摘要

The objectives of this study were to (1) characterize the geomorphic attributes of the present channel and alluvial valley of the lower Duchesne River between the mouth of the Uinta River and the Green River; (2) evaluate the flows, sediment transport, and channel processes that formed and maintained the present channel/valley system; (3) evaluate the degree to which the present channel/valley system is in a state of dynamic equilibrium with recent stream flows; and (4) determine the discharges necessary to insure that existing geomorphic and habitat conditions can be maintained in the future. Our strategy for meeting these objectives employed an historical analysis of geomorphic change in the study area, in addition to more traditional methods of characterizing modern fluvial geomorphic processes. Analysis of historical aerial photography in a geographic information system (GIS) was used to quantify past channel responses, and the record of channel change was compared to changes in water and sediment discharge. This comparison allowed us to determine the role of decade-scale periods of high and low flow in forming and maintaining the channel and valley of the Duchesne River. The form and functioning of the present river was quantified through extensive field measurements of channel and valley characteristics, and through the use of computational methods.