Evaluating SEDCAD Model Performance on Reclaimed Coal Mine Lands in East Tennessee

The Sediment, Erosion, Discharge by Computer Aided Design (SEDCAD) program is extensively used in the mining industry for engineering site layout plans with best management practices (BMPs) for erosion control. Although SEDCAD is the primary BMP design tool used in this industry, very limited published information is available on its performance estimating site runoff and sediment yields. This study compared sediment yields from three surface coal mining sites in east Tennessee with SEDCAD modeled outputs. Study sites included active mining operations on steep slopes (>20 degrees) where after mining, approximate natural hillslope contours were reconstructed by using loose spoil materials on top of slope, at shallow depths of 1-2 m, following the Forest Reclamation Approach. The SEDCAD model inputs included the site-derived hydrologic curve number (CN) of 59 and average erodibility K factors ranging from 0.001-0.034 Mg . ha . h . ha(-1) . MJ(-1) . mm(-1) varying on the basis of pre- and postrill development periods and mining site. The SEDCAD overestimated sediment yields as a function of erosivity (R) up to 1.6 times greater than the minimally measured yields in two of the three study sites. A sensitivity analysis of input parameters found CN selection can greatly affect modeled outputs for sediment yield. For example, a 40% deviation in selecting a CN would double the computed sediment yield. Results from this study provide design engineers using SEDCAD a better understanding of the uncertainty with model outputs to improve selection and design of erosion BMPs on surface coal mining sites. DOI: 10.1061/(ASCE)IR.1943-4774.0000540. (C) 2013 American Society of Civil Engineers.