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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #186464
Title: EVALUATION OF THE IMPORTANCE OF CHANNEL PROCESSES IN CEAP-WATERSHED SUSPENDED-SEDIMENT YIELDS

Author
item Simon, Andrew

Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/4/2006
Publication Date: 4/4/2006
Citation: Simon, A. 2006. Evaluation of the importance of channel processes in CEAP-watershed suspended-sediment yields. In: Proceedings of the 8th Federal Interagency Sedimentation Conference, April 2-6, 2006, Reno, Nevada. CDROM.

Interpretive Summary: Sediment is one of the principal pollutants of surface waters of the United States. Efforts by the U.S. Department of Agriculture to quantify and control sediment erosion have historically focused on fields and upland areas. There is a growing body of evidence in agricultural areas of the mid-continent that the main source of sediment erosion has shifted from fields and uplands to edge of field gullies and channels. A methodology has been developed and tested to determine regional sediment loads and whether these loads represent stable or unstable conditions. The paper outlines a research approach to be applied to watersheds under the joint NRCS-ARS Conservation Effects Assessment Program.

Technical Abstract: Sediment is one of the principal pollutants of surface waters of the United States. Efforts by the U.S. Department of Agriculture to quantify and control sediment erosion have historically focused on fields and upland areas. There is a growing body of evidence in agricultural areas of the mid-continent that the locus of sediment erosion has shifted from fields and uplands to edge of field gullies and channels. Rapid geomorphic assessments (RGAs) of benchmark watersheds in the Conservation Effects Assessment Program (CEAP) are used to determine the degree of instability and stages of channel evolution throughout the channel systems. The distribution of stages throughout the channel network identify local versus systematic disturbances and whether channels are important contributors of sediment. Stable, reference conditions are identified from stages I and VI and used as a means of comparing suspended-sediment yield data from the CEAP watersheds to regional values. Data from more than 2,900 sites across the United States were analyzed in the context of estimating flow and suspended-sediment transport conditions representing average, annual and at the 1.5-year recurrence interval (Q1.5) discharge. Data were sorted into the 84 Level III ecoregions to identify spatial trends in suspended-sediment concentrations and yields. Suspended-sediment yields for stable streams are used to determine “background” or “reference” sediment-transport conditions and to compare with values obtained from the monitored CEAP watersheds.