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United States Department of Agriculture

Agricultural Research Service

Title: Rill Erosion and Morphological Evolution: I. Theoretical Relationships

Authors
item Nearing, Mark
item Lei, T - PURDUE UNIV., WLAF, IN
item Haghighi, K - PURDUE UNIV., WLAF, IN
item Bralts, V - PURDUE UNIV., WLAF, IN

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 1998
Publication Date: N/A

Interpretive Summary: Models of soil erosion generally have two possible purposes. Some models, such as the Universal Soil Loss Equation or the WEPP model, are intended for conservation planning purposes, i. e., they are used to predict the amount of erosion from farm fields given different management options. Other models serve the purpose of helping us understand the science of erosion. The model presented in this study falls within the latter category, by mimicing the way in which rills form and change over time. It also uses more advanced physics with a much higher level of complexity than has been used in previous scientific investigations. In studying the behavior of the model scientists can better understand how erosion occurs, but perhaps more importantly, it helps us to understand how better to measure soil erosion and how to build better models for soil conservation purposes.

Technical Abstract: A mathematical model is advanced to simulate dynamically and spatially varied shallow water flow and soil detachment, transport, and deposition in rills. The model mimics the dynamic process of rill evolution, including temporal changes in the spatial heterogeneity of rill flow width, depth, and velocity effected by variable rates of sediment redistribution along the bed and associated with changes in local bed slope, sediment loads, and transporting capacity. The model is based on full hydrodynamics, including inertial terms. The sediment source term in the model uses a point scale, probabilistic relationship based on turbulent flow mechanics, and a recently developed sediment transport relationship based on stream power. The interdependent feedback loops between channel bed morphology, local flow hydraulics, and local scour and deposition, within the framework of the full hydrodynamic equations with inertial terms, constitute a rill model with the capacity to represent spatial variability and temporal evolution of the rill. Finite elements were applied to numerically solve the hydrodynamic and sediment continuity equations.

Last Modified: 12/21/2014
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