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United States Department of Agriculture

Agricultural Research Service

Title: The Surface Impoundment Element for Wepp: Part I: Hydraulic Simulation

Authors
item Lindley, Mark - OKLAHOMA STATE UNIVERSITY
item Barfield, Billy - OKLAHOMA STATE UNIVERSITY
item Ascough, James
item Wilson, Bruce - UNIV. OF MINNESOTA

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 1997
Publication Date: N/A

Interpretive Summary: The USDA-Water Erosion Prediction Project (WEPP) model was developed to estimate runoff and sediment yield for small agricultural watersheds located throughout the United States. WEPP user requirements dictate that the impoundment component must simulate the hydraulic response of several types of impoundments including farm ponds, terraces, culverts, filter fences, and check dams. Algorithms and computer code for the hydraulic simulation portion of the WEPP Surface Impoundment Element (WEPPSIE) were developed and validated for a variety of possible impoundment geometries and outflow structures (e.g., drop spillways and perforated risers). Hydraulic routing is performed by a direct numerical integration of an expression of continuity. Continuous algorithms are used to determine the discharge and area as functions of stage in the hydraulic routing. The hydraulic routing procedure was validated against the PULS routing method included in the impoundment components of the SEDIMOT and SEDCAD models. The hydraulic routing procedure performs well and is a significant improvement over the PULS routing procedure used in SEDIMOT and SEDCAD. Stage-discharge relationships for perforated risers, open channels, emergency spillways, and rock fill check dams were also validated and performed well. Taken as a whole, WEPPSIE satisfied the impoundment user requirements of the WEPP model by producing reasonable predicitions of the hydraulic routing of flow for impoundments covering a wide range of geometries and outflow structures.

Technical Abstract: The hydraulic algorithms included in the Water Erosion Prediction Project Surface Impoundment Element (WEPPSIE) are described and validated in this paper. Algorithms and computer code were developed to perform hydraulic routing in impoundments with a wide variety of geometries and outflow structures including drop spillways, perforated risers, culverts, open channels, emergency spillways, rock fill check dams, filter fences, and straw bales. Hydraulic routing was performed using a direct numerical integration of an expression of continuity with analytical stage-area and stage-discharge functions. The hydraulic routing results were validated against those obtained using the well established PULS routing procedure included in the CSTRS model. The proposed approach was in good agreement with the PULS results. Stage-discharge relationships for perforated risers, open channels, emergency spillways, and rock fill check dams were also validated and performed well. Taken as a whole, WEPPSIE satisfied the impoundment user requirements of the WEPP model by producing reasonable predictions of the hydraulic routing of flow for impoundments covering a wide range of geometries and outflow structures.

Last Modified: 12/19/2014
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