Predicting runoff from Variable Source Area

Authors: Panjabi, K., R. Rudra, B. Gharabaghi
Description: Majority of current water quality models implicitly assume that runoff is generated through infiltration excess overland flow. However, in humid, well-vegetated areas with shallow soils, the predominant runoff generating mechanism is saturation-excess on variable source areas (VSAs). Therefore these models are not able to correctly locate the runoff generating areas as the factors that control soil infiltration rates are different from the factors that control VSAs. In this study a modelling approach was developed using event based distributed AGNPS model to simulate and identify the runoff generating areas based on VSA hydrology concepts. The modeling approach of Agricultural. Non-Point Source (AGNPS) Pollution model was modified to distribute overland flow in ways consistent with VSA hydrology by incorporating Topographic Wetness Index (TWI). The AGNPS-VSA model showed good agreement with observed runoff and runoff source areas were correctly identified. The developed model showed good potential for land management applications in agricultural watersheds where farmers and watershed managers are developing strategies to minimize pollutant loadings to surface waters by accurately predicting the locations of critical runoff generating areas.
Keywords: Variable source area, SCS runoff curve number, Saturation excess runoff, Topographic wetness index, Nonpoint Source Pollution.
Technical field: Soil and Water Systems Engineering
Conference name: CSBE/SCGAB 2015 Annual Conference, Edmonton, AB, 5-8 July 2015.
Session name: Water Management II - Structures and Modelling
Citation: Panjabi, K., R. Rudra, B. Gharabaghi. 2015. Predicting runoff from Variable Source Area
Publisher: Canadian Society for Bioengineering
Date: 2015-07-05
Publication type:
  • Technical conference
Type: Text.Article
Identifier: CSBE15116
Coverage: Canada
Language 1: en
Rights: Canadian Society for Bioengineering

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