Analyzing Sediment Yields in the Context of TMDL's
Madej M, Klein R, Ozaki V, Marquette T. Analyzing Sediment Yields in the Context of TMDL's. In Proceedings of the Eighth Federal Interagency Sedimentation Conference. Reno, Nevada. April 2-6, 2006. Subcommittee on Sedimentation. Reno, Nevada
Abstract: "In 1998, the California Regional Water Quality Control Board established a Water Quality Attainment Strategy for Sediment and Total Maximum Daily Loads (TMDL) for Redwood Creek, California. In the TMDL, a 10-year rolling average of sediment yield of 1900 t of total sediment/mi^2/year (equivalent to about 500 Mg of suspended sediment/km^2/yr) was used as a threshold of concern. We investigate the relevance of this value by analyzing trends in suspended sediment yields at two gaging stations in Redwood Creek, north coastal California. The TMDL reported that at both the upstream and downstream gaging stations, the 10-year rolling average exceeded the threshold between 1973 and 1992, and was below threshold from 1993-1996. A comparison of suspended sediment-discharge rating curves shows a significant shift from higher sediment transport rates in the 1970's (following large storms and extensive landslide activity) to lower rates in the 1980's and 1990's, and even lower rates in the 2000's. In recent years the upstream and downstream gaging stations, monitoring sediment transport from drainage areas of 175 and 725 km^2, respectively, have similar sediment concentrations on a per unit area basis. This lack of a significant shift in sediment transport curves suggests that the trends in the TMDL rolling average are more dependent on flow magnitude rather than being indicative of changes in sediment transport relationships in the basin."
- Type
- Conference Proceeding Paper
- Authors
- Madej, Mary Ann; Klein, Randy; Ozaki, Vicki; Marquette, Tom
- Units
- REDW
- Keywords
- landslides, Redwood Creek, sediment transport, TMDL, water quality, watershed