December 1993.Includes bibliographical references (pages 61-64).This paper reports on a study of regime, bedload transport, and channel morphology in diverted and free-flowing segments of mountain streams in Colorado where flow has been diverted, in some cases, for up to one hundred years. The goal of the project was to determine whether differences in channel form and processes could be detected and linked to changes in flow regime from diversion. The effect of diversion on flow fegime can very considerably between individual steams. Typically, the total annual water yield is drastically reduced by diversion, though, where storage is limited, occasional high flows, with a five-to-ten year return frequency, move thought the natural channel. These larger events have the potential to reset changes in morphology incurred during the intervening dry years, such as channel narrowing and fining of bed size distribution. In general, changes in channel capacity were quite subtle, and the most apparent change was a decrease in channel width due to vegetation and the development of low bank beneath a former cut bank. No change in morphology was apparent in constrained channels. The results here are preliminary as of December 1993. Final results will be presented in subsequent publications.Grant no. 14-08-0001-2008, Project no. 13; financed in part by the U.S. Dept. of the Interior, Geological Survey, through the Colorado Water Resources Research Institute
