| Accelerated soil erosion is a serious problem because it destroys the land were it occurs and the resulting sediment pollutes the waters where it is carried and deposited. Experimental studies have led to the development of empirical equations describing soil erosion. Mathematical representations of the physical relationships involved in soil erosion require consideration of rainfall, overland flow, erosion, sediment transport and soil surface changes due to erosion.;Simulated runoff, erosion-sediment routing and soil surface degradation compared favorably with observed data. Soil surfaces were adequately represented in the simulations by a roughness index and approximations of the profiles. Better hydrographs were obtained when Manning's equation was used as the overland flow resistance equation. Rill and interrill erosion concepts were more practical for use in numerical simulations and carried more physical meaning.;The computer programs and procedures developed can be useful in studying erosion concepts, sediment transport and yield, overland flow and erosion-sediment transport interrelationships, and soil surface degradation due to erosion.;Dynamic overland flow equations and conservation of mass equations for sediment were numerically solved to simulate overland flow, erosion, sediment routing and soil surface degradation from small fallow test plots located in unmined soils and soils reclaimed from strip mining operations. Infiltration was estimated using a soil moisture dependent equation. Resistance to overland flow was represented using Manning's equation or a semilogarithmic equation based on Prandtl's mixing length theory. Erosion rates were computed using rill and interill erosion concepts or splash and flow erosion ideas. Soil surfaces were described using profiles. |
