RUNOFF-ENERGY FACTORS FORMUSLE SEDIMENT-YIELD MODEL FOR SURFACE MINES

The Modified Universal Soil Loss Equation (MUSLE) is often used for sediment-yield estimations insurface mines for design and impact evaluations. However, it is not known if the widely-used runoff-energy factor of MUSLE is appropriate, or if its parameters are the same for surface mines as foragricultural watersheds from which MUSLE was developed. Suspended-sediment data from threeexperimental watersheds in Ohio (approximately 1O - 2O ha), subjected to near complete distUrbance dueto mining and reclamation, were used to investigate five altemate runoffenergy factors in the MUSLEsediment-yield model for use in surface mines. The evaluation led to the selection of the generalizedmodel form, a (runoff volume X peak flow rate)b, as the best choice among models investigated.Exponent b was greater than the widely-used value of 0.56, ranging from 0.68 to 1. 10. Parameter b wasdependent on whether mining-or reclamation-related watershed activities were predominam. Theoriginal Williams (1975) model fit the data least well of the five energy factors studied.