Hydraulic roughness of earth covers at a cold-desert waste burial site

A kinematic wave model of overland flow was used to calculate hydraulic roughness coefficients for earth covers and native hillslope surfaces at a waste burial site. Manning's n roughness coefficients were greater on earth cover plots planted to crested wheatgrass (n = 0.076) than on those planted to streambank wheatgrass (n = 0.030). Mound and intermound microtopography strongly influenced overland flow geometry on the bare native hillslope plots resulting in low apparent roughness values (n = 0.013). Time-related changes in hydraulic roughness appeared to be caused by development of a rain-induced crust on exposed soil surfaces that reduced infiltration and increased plot smoothness. -from Authors