Fine sediment storage in pools in gravel-bed Russian River, California

摘要

Changes in fine sediment storage in two pools located in the Russian River in Northern California were monitored during 2002-2007. The purpose of the monitoring was to determine impact of bar mining on fine sediment supply into the river. One monitored pool was located in a natural river reach with no mining, while the other pool was within the mining reach. The measurements were conducted during low water periods when a significant portion of fine sediment had accumulated in pools. The fraction of the pool volumes filled with fine sediment (V*) ranged from 0.24 to 0.47 in the natural reach and from 0.27 to 0.44 in the mining reach. The measured V* values were affected by the magnitude and duration of high flows, seasonal variation in sediment supply, and natural channel evolution processes. Similar V* values and their temporal variations were observed in the natural and mined reach of the river, which indicate that mining activities did not contribute detectible amounts of fine sediment into the river system. The collected data provide a useful insight into the process of fine sediment transport and storage in the dynamic channel of the Russian River.