|Rebich, Richard - USGS|
Submitted to: International Association on Water Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 1999
Publication Date: N/A
Interpretive Summary: Diffuse pollution in the southern United States is of major concern because of the region's abundant water resources. The Yazoo River Basin has two distinct physiographic regions within its drainage area. The upland streams have relatively steep slopes and are deeply incised. The region is largely forested with some agricultural areas. In contrast, the Delta has low slopes with backwater flooding, and is one of the most productive agricultural areas in the Nation. Sediment and diffuse pollution from agricultural activities is of concern to both regions. The research presented here addresses the simularities and differences in diffuse pollution from the two regions, defines the role of sediment and transient storm events in nutrient transport, and illustrates the effectiveness of selected best management systems (BMPs) in the remediation of diffuse pollution. This research will assist resource managers develop farm management plans to improve the water quality/ecology of the Yazoo River Basin.
Technical Abstract: An understanding of diffuse pollution from the southern region of the United States demands that information be known on the source of pollutants, quantities in transport, mode of transport, transient nature of the pollution event, and most importantly, a consideration of remediation efforts. For example, water quality research in the Yazoo Basin in Mississippi has shown sediment loads from a conventional-till upland soybean watershed to be about 19,000 kg/ha/yr, and responsible for 77 to 96% of P and N in transport. In contrast, sediment loads from a comparable no-till soybean watershed were only 500 kg/ha/yr, transporting about 31% of P and N in transport. Sediment loads from a nearby forested area were low, about 200 kg/ha/yr, but responsible for about 47 to 76% of P and N in transport. Transient pollution events are responsible for the transport of large quantities of sediment, nutrients, and pesticides; in some storm events nearly the annual load. Best management practices (BMP's) must be designed to remediate diffuse pollution and the transient nature of pollution events which can have a profound effect on the ecological health of steams and reservoirs