Submitted to: Management of Landscapes Disturbed by Channel Incision Stabilization Rehabi
Publication Type: Proceedings
Publication Acceptance Date: April 15, 1997
Publication Date: N/A
Interpretive Summary: The accurate prediction of the effect of land use changes on the movement of sediment in a watershed is critical information for land managers. For small land areas the effect of land use on the movement of water and sediment has been demonstrated by several studies. For larger areas, however, many complicating factors make the relation between land use and water and sediment movement difficult to predict accurately. The information collected on the Goodwin Creek Experimental Watershed has allowed the effect of changing land use on the movement of sediment and water to be evaluated. The percentage of cultivated land on Goodwin Creek decreased from 26% in 1982 to 12% in 1990. Rates of sediment movement, measured as a concentration of sediment in the runoff, decreased by 62%, 66%, and 39% for the fine, sand, and gravel fractions over the period form 1982 to 1990. The decrease in the percentage of cultivated land affects the movement of sediment through the watershed in two ways. A source of readily eroded sediment is removed and the energy of the flowing water available to move sediment is reduced. Thus, to reduce erosion in a large watershed, it is important to not only control the supply of sediment to the channel, but also to control the supply of water to the channels.
Technical Abstract: The Goodwin Creek Research Watershed (21.3 square kilometers) is located in the north central part of the state of Mississippi in the bluff hills just east of the Mississippi River flood plain. Land use on the watershed has been surveyed annually and the percentage of cultivated land has decreased from 26% in 1982 to 12% in 1990. During this nine year period the concentraiton of fines (<0.062 mm) in Goodwin Creek have decreased by 62%, concentrations of sand (0.062-2.0 mm) have decreased by 66%, and concentrations of gravel (>2.0 mm) have decreased by 39%. A decrease in the percentage of cultivated land affected the sediment budget of the watershed in two ways. A source of readily eroded sediment was removed, and the energy of the flowing water available to erode and transport sediment was reduced. The reduced flow in the channels from the decrease in cultivated land in the watershed was probably the main cause for the lower transport rates of sand and gravel.