A Model to Estimate Sediment Yield from Field-Sized Areas: Development of Model

A tool for evaluating sediment yield from field-sized areas is needed for planning management practices to control sediment yield. We developed a reasonably simple simulation model which incorporates fundamental principles of erosion, deposition, and sediment transport mechanics. The model summarizes the state-of-the-art in erosion and sediment yield modeling with appropriate simplifications required to couple the governing equations. Limited testing showed that the procedures developed here give improved estimates over the Universal Soil Loss Equation. Specific components of the model were tested using experimental data from overland flow, erodible channel, and impoundment studies. These results suggest that the model produces reasonable estimates of erosion, sediment transport, and deposition under a variety of circumstances common to field-scale areas. Alternative management practices such as conservation tillage, terracing, and contouring can be evaluated separately or in combination to determine their influence on sediment yield. Given a particular location with specified characteristics for climate, soils, topography, and crops, the model provides a means of evaluating alternative management practices to suit a particular farming operation

Sediment delivery on rill and interrill areas

Equations which relate sediment delivery to a power function of flow rate and slope gradient were evaluated in this study. The data used to parameterize the equations were obtained from sites where crop residues had been removed, and moldboard plowing and disking had occurred. Measurements of sediment delivery resulting from simulated rainfall were obtained from preformed rills and interrill areas. The equations provided reliable sediment delivery estimates for selected soils located throughout the United States. To use the sediment delivery equations, soil-related parameter values must be identified. Multiple regression analyses were performed to relate parameter values used in the equations to selected soil properties. Equations were also developed for estimating rill sediment delivery under rainfall conditions from rill soil loss and discharge data collected without the addition of rainfall. The equations identified in this study, and appropriate soils information, can be used to predict sediment delivery on both rill and interrill areas