Predicting Mean Annual Runoff and Suspended Sediment Yield in Rural Watersheds in211 North Carolina

摘要

Measured mean annual runoff (Q) and suspended sediment yield (SSY) from selected211u001erural watersheds in the Coastal Plain, Piedmont, and mountain regions of North 211u001eCarolina were used to develop regression equations to predict Q and SSY as a 211u001efunction of climatic and watershed characteristics. The selected independent 211u001evariables for prediction of Q were mean annual precipitation and main channel 211u001eslope for the Coastal Plain, and the ratio of mean annual precipitation to mean 211u001eannual temperature for a combined equation for the Piedmont and mountain regions. 211u001eThe selected independent variables for predicting SSY were percent of watershed 211u001eareas upstream of ponds and percent of forest cover for the Coastal Plain; 211u001ewatershed mean elevation, estimated mean annual gross erosion, road density, 211u001edrainage density, and percent of watershed upstream of ponds for the Piedmont; 211u001eand watershed mean elevation and percent of cropland for the mountain region. 211u001eRegression equations to predict monthly and annual mean air temperature and mean 211u001eair temperature ranges were also derived using 57 meteorological stations with 30-211u001eyear records of temperature. A procedure for predicting maximum and minimum 211u001etemperatures was also developed. An estimate of the temperature lapse rates due 211u001eto elevation and latitude was proposed. Finally, a study was conducted to select 211u001ea sampling procedure and determine the required sample size for estimating 211u001edrainage density (Dd) in watersheds less than 1,100 sq km in area.