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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #312739

Title: The potential for agricultural land use change to reduce flood risk in a large watershed

Author
item SCHILLING, KEITH - IOWA DEPARTMENT OF NATURAL RESOURCES
item GASSMAN, PHILIP - IOWA STATE UNIVERSITY
item KLING, CATHERINE - IOWA STATE UNIVERSITY
item CAMPBELL, TODD - IOWA STATE UNIVERSITY
item JHA, MANOJ - NORTH CAROLINA AGRICULTURAL AND TECHNICAL STATE UNIVERSITY
item WOLTER, CALVIN - IOWA DEPARTMENT OF NATURAL RESOURCES
item Arnold, Jeffrey

Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2013
Publication Date: 10/29/2014
Publication URL: http://handle.nal.usda.gov/10113/60416
Citation: Schilling, K.E., Gassman, P.W., Kling, C.L., Campbell, T., Jha, M.K., Wolter, C.F., Arnold, J.G. 2014. The potential for agricultural land use change to reduce flood risk in a large watershed. Hydrological Processes. 28:3314-3325.

Interpretive Summary: The effects of agricultural land management on large river basins is not well understood. In this study, the SWAT (Soil and Water Assessment Tool) model was used to assess the impact of land use in the Raccoon River watershed in Iowa. Model results indicate that the frequency and severity of floods could be reduced with land use change. The greatest reduction in flooding was associated with converting all cropland to perennial vegetation. Results showed that large scale land use conversion would be required to significantly reduce flooding.

Technical Abstract: Effects of agricultural land management practices on surface runoff are evident at local scales, but evidence for watershed-scale impacts is limited. In this study, we used the Soil and Water Assessment Tool model to assess changes in downstream flood risks under different land uses for the large, intensely agricultural, Raccoon River watershed in Iowa. We first developed a baseline model for flood risk based on current land use and typical weather patterns and then simulated the effects of varying levels of increased perennials on the landscape under the same weather patterns. Results suggest that land use changes in the Raccoon River could reduce the likelihood of flood events, decreasing both the number of flood events and the frequency of severe floods. The duration of flood events were not substantially affected by land use change in our assessment. The greatest flood risk reduction was associated with converting all cropland to perennial vegetation, but we found that converting half of the land to perennial vegetation or extended rotations (and leaving the remaining area in cropland) could also have major effects on reducing downstream flooding potential. We discuss the potential costs of adopting the land use change in the watershed to illustrate the scale of subsidies required to induce large-scale conversion to perennially based systems needed for flood risk reduction.