Sediment Supply and Flow in the Colorado River Basin

Lucas Siegfried

Abstract: The Colorado River Basin is one of the most regulated basins in the world, supplying water to communities in Colorado, Utah, Nevada, Arizona, California, and Mexico. Humans and climate change have increased the variability of stream flows and sediment transport within the Colorado River Basin, affecting riparian ecosystems, water resources management, and coastal environments. To assess how global changes, including the influences of humans and climate change, in the Colorado River Basin have impacted the sediment transport flow regime within the basin, concepts of fluvial geomorphology followed by a review of the Colorado River Basin, and the effects of dams and climate change within the basin are presented. Although the tributaries in the upper Colorado River Basin contribute most of the flow to the Colorado River, sediment is contributed primarily from the semi-arid tributaries of the lower basin. Due to the different sources of flow and sediment, the downstream effects of reservoirs not only depend on the size and operation schedule of the reservoir, but also the location. Alterations to the Colorado River Basin from reservoirs have changed the sediment transport regime of the Colorado River in complex longitudinal patterns. Changing climate characteristics are expected to lead to increased sediment yields as well as changes in the timing and magnitude of peak flows in the Colorado River Basin. However, due to the large storage capacity of the reservoirs within the Colorado River Basin, the flows of the Colorado River are not expected to change significantly, but an overall increase in sediment yield within the Colorado Basin from global change, having reach dependent impacts, is expected.