Variability of Sediment and Salt Loads in the Upper Colorado River Basin: Significance for Conservation and Management. Phase 1

摘要

The objective of the research was to investigate both sediment and salt loads in the upper Colorado River basin and to determine the reason for any change. Analysis of sediment and salt load data shows that, although affected by hydrologic variability, both sediment (6 stations) and salt (14 stations) loads have decreased since about 1935. Aerial reconnaissance and field surveys show that the incised channels (arroyos), that once supplied large quantities of sediment to the Colorado River, during the period starting about 1880, have widened. In addition, new flood plains have formed. Decreased sediment production from upstream tributaries and from the channel side walls, and sediment storage in the flood plains, all appear to be the reason for the significant regional reduction of sediment loads. Reduced erosion and sediment storage also may account for the reduced salt loads.