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Research Project: Strategic Investigations to Improve Water Quality and Ecosystem Sustainability in Agricultural Landscapes

Location: Water Quality and Ecology Research

Title: Characterizing ponds in watershed simulations and evaluating their influence on streamflowin a Mississippi Watershed

Author
item Yasarer, Lindsey
item Bingner, Ronald - Ron
item Momm, Henrique

Submitted to: Hydrological Sciences Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Small water bodies such as farm ponds are commonly found in agricultural watersheds, but they are typically not represented in watershed model simulations. The influence of these ponds on local and regional hydrology should be accounted for. ARS scientists at the National Sedimentation Laboratory utilized a wetland modeling tool (AgWET) to characterize farm ponds within the Goodwin Creek Experimental Watershed in Mississippi. AgWET was able to correctly estimate pond size and shape, while providing characteristics necessary for watershed simulations. The Annualized Agricultural Non-Point Source pollution model, AnnAGNPS, then simulated the hydrological impacts of these ponds within the watershed. It was found that ponds lowered annual mean flow by 4% at the watershed outlet and reduced local flows by an average of 56% immediately downstream of ponds. Overall, this tool improved the accuracy of watershed hydrology simulations in Goodwin Creek Experimental Watershed at various scales.

Technical Abstract: Small water bodies are common landscape features, but often are not simulated within a watershed modeling framework. The wetland modeling tool, AgWET, uses a GIS framework to characterize the features of ponds and wetlands so that they can be incorporated into watershed simulations using the Annualized Agricultural Non-Point Source (AnnAGNPS) pollution model. AgWET was used to characterize farm ponds on the Goodwin Creek Experimental Watershed in northwest Mississippi and AnnAGNPS simulated watershed hydrology. Monthly streamflow was validated at four watershed gauges with Nash-Sutcliffe efficiency values between 0.91 and 0.94. Ponds influenced watershed hydrology at various scales, with a decrease in average streamflow by 4% at the watershed outlet, 8% at the sub-watershed scale, and an average of 56% immediately downstream of the ponds. AgWET can be used to simulate ponds in watershed assessments for improved results and evaluation of future scenarios.