Modified Universal Soil Loss Equation (MUSLE)

The USLE was modified by Williams in 1975 to MUSLE by replacing the rainfall energy factor (R) with another factor called as ‘runoff factor’. The MUSLE is expressed as

Y = 11.8 (Q x qp)^0.56 K(LS) CP

where, Y = sediment yield from an individual storm (in metric tones), Q = storm runoff volume in m3, and qp = the peak rate of runoff in m3/s.

All other factors K, (LS), C, and P have the same meaning as in USLE. The values of Q and qp can be obtained by appropriate runoff models. In this model, Q is considered to represent the detachment process and qp is the sediment transport. It is a sediment yield model and does not need a separate estimation of sediment delivery ratio and is applicable to individual storms. Also, it increases sediment yield prediction accuracy. From a modeling point of view, it has the advantage that daily, monthly, and annual sediment yields of a watershed can be modeled by combining appropriate hydrological models with MUSLE.