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United States Department of Agriculture

Agricultural Research Service

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The National Sedimentation Laboratory is located in one of the highest sediment producing areas of the United States. The upland soils in this region are highly erodible, the climate is highly erosive, and major crops like cotton and soybeans leave little residue to protect against erosion. Stream channels in the area are highly erodible and unstable. Within a short time, channels can widen at a location from about 15 ft wide and 5 ft deep to about 50 ft wide and 15 ft deep. Tremendous sediment loads are produced that create downstream sedimentation problems in the Mississippi Delta and elsewhere that almost totally destroy the ecological well being of the local streams, cause downstream flooding, and destroy wetlands. Pesticide use on cotton is very high, creating the potential for excessive amounts of contaminant movement into surface and subsurface water. Persistent compounds like DDT were heavily used in the past and are still detected in sediments. In the upland areas near the laboratory, slopes are steep that contribute to excessive erosion. In the near-by Delta, a major crop producing area, slopes are flat, often one percent or less, but erosion and sediment delivery from these fields approaches 10 tons/acre per year. Much of the sediment leaving Delta fields is fine, causing water quality degradation as a contaminant itself and as a carrier of contaminants. This setting provides an ideal location to study processes, control measures, and prediction technology associated with water,erosion, sediment, and agricultural chemicals.


Last Modified: 3/7/2006
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