Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2008
Publication Date: 11/3/2008
Citation: Kuhnle, R.A., Bingner, R.L., Alonso, C.V., Wilson, C.G., Simon, A. 2008. Conservation Practice Effects on Sediment Load in the Goodwin Creek Experimental Watershed. Journal of Soil and Water Conservation 63(6): 496-503. Interpretive Summary: Accurate evaluations of the effect of conservation practices on the movement of sediment on agricultural watersheds are required for effective and environmentally responsible land management. Previous studies have shown that for small areas management practices are critical factors in the rate at which sediment is moved off the land. In larger areas, however, many complex factors make the relation between land management practices and the amount of soil and sediment erosion more difficult to predict. The effects of changing management and agricultural practices on the rate of sediment loss was calculated for a period of over twenty years using flow records and samples of moving sediment for the Goodwin Creek Experimental Watershed in north central Mississippi. As land use and management practices have changed the rates of sediment movement have decreased by nearly two thirds on the watershed. The construction of erosion-control structures on the watershed has shown that simulated rates of sediment movement on the watershed have been reduced by from 15 to over 200 percent. The knowledge learned in this study will lead to more accurate methods to predict the effect of management practices on agricultural lands. This information will allow lands in agricultural watersheds to be managed in a more environmentally sustainable manner.
Technical Abstract: The 2132 ha (5266 acres) Goodwin Creek Experimental Watershed (GCEW) has been in operation since October, 1981 to collect information to improve the understanding of the movement of water and sediment in a north Mississippi agricultural watershed. The primary environmental concerns of the watershed are the quality of the water and aquatic habitat affected by unstable channel conditions and high sediment concentrations during storm runoff events. The use of instream structures and the conversion of erodible lands to the Conservation Reserve Program (CRP) status were studied to determine their effects on total sediment concentrations and channel stability. Analysis of total sediment load derived from measurements have determined that the conversion of erodible lands to CRP status has reduced total sediment concentrations by 63 percent. Model simulations indicate that the placement of a series of instream grade control structures has reduced mean sediment yields from 15 to over 200 percent. Studies are continuing to refine and improve these determinations.