Hydraulics of Failure of Unanchored Cornstalk and Wheat Straw Mulches for Erosion Control

ABSTRACT BASIC hydraulic theory that divides a flow's total shear stress into that acting on soil and that acting on mulch was used to derive equations giving critical slope length for failure of unanchored mulch on untitled soils as a function of mulch type (cornstalk or wheat straw) and amount, slope, rainfall erosivity, runoff, and soil susceptibility to rill erosion. Parameter values for the equations were determined from experimental data. Values computed from the equations agreed well with recommended values for wheat straw mulch on construc-tion sites for slopes greater than 13 percent. Graphical solutions to the equations were prepared to facilitate ap-plication of the analysis.