Problems regarding the relationship and effect of shear stress components (hydraulic and viscous shear stresses) on erosion in overland flows were considered. Empirical relationships were proposed for calculating the viscous shear stresses in the overland flows upon rainstorms. Only hydraulic shear stresses are considered presently in research and design work on the simulation of erosion and sediment transport [6, 8, 11-14]. This is related to the fact that hydraulic shear stresses are usually significantly higher in absolute value than viscous shear stresses. It is believed that shear stresses are mainly determined by viscous friction in laminar flows and by turbulent friction in turbulent flows [1, 9]. In the general case, an average flow has both molecular and turbulent viscosities. Therefore, the total shear stress T(N/m2) for an average flow is the sum of the turbulent (hydraulic) i, and viscous tv, shear stresses.
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