Overland flow partitioning for rill and interrill erosion modeling

Abstract

Accurate estimation of the shear stress of flowing water is important in modeling rill and interrill erosion. The shear stress of flow in rills helps determine detachment capacity and transport capacity of flow. This study investigated shear stress estimation in erosion modeling. Rill shear stress estimates based on sheet flow and on flow partitioned into rill and interrill areas for a uniform slope were compared. It was found that the sheet flow assumption underestimated actual shear stress in rills. Estimates of rill spacing and rill width affect shear stress in rills. It was found that increasing the distance between rills could increase predicted sediment loads while sediment loads reached a maximum then decreased for increased rill widths. Erodibililty parameters for an erosion model were found using optimization. Optimal values for rill erodibility parameters were found to be distorted when based on a model that estimated shear stress from sheet flow.