Assessment of irrigation reservoir levee impairment in Arkansas, USA

Authors: Wren, Daniel; OZEREN, YAVUZ - National Center For Agriculture And Forestry Technologies (CENTA); Taylor, Jason; Reba, Michele; BOWIE, CHAROLETTE - Natural Resources Conservation Service (NRCS, USDA)

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2018
Publication Date: 9/15/2018
Citation: Wren, D.G., Ozeren, Y., Taylor, J.M., Reba, M.L., Bowie, C. 2018. Assessment of irrigation reservoir levee impairment in Arkansas, USA. Journal of Soil and Water Conservation. 73(5):533-540. https://doi.org/10.2489/jswc.73.5.533.
DOI: https://doi.org/10.2489/jswc.73.5.533

Interpretive Summary: Increasing demands on limited groundwater resources have created a growing need for the development of surface water resources for irrigation. Reservoirs can be used for this purpose, but levees can be rapidly eroded by both wind-driven waves and surface runoff if they are not properly protected. In order to assess the degree of impairment for irrigation reservoir levees and to provide information that can be used to design or retrofit levees so they can be more resistant to erosion, the characteristics of 148 levees located in Arkansas were analyzed in search of factors that contribute to excessive levee erosion. It was found that 79% of the levees had significant damage and that the most important factor related to damage was the maximum length of water over which wind could blow. Limiting this distance by adding interior levees or floating wave barriers may provide a way to reduce the likelihood of damage due to wind-driven waves.

Technical Abstract: The use of surface water resources in the state of Arkansas increased over the years following 2000 because of groundwater depletion. In order to reduce dependence on groundwater, irrigation reservoirs and tailwater recovery systems are used to capture and store water for irrigation. Irrigation reservoir levees are typically constructed from local soils that are often low in cohesion, and the use of rock armoring and geotextiles is limited due to high costs, resulting in levees that are susceptible to erosion. Wind-driven waves erode the exposed inner slopes of the levees, resulting in the need for frequent repairs, an added expense for agricultural producers. Evaluation of the status of irrigation storage reservoirs and identification of design factors that contribute to erosion are needed to address the problem. A survey was conducted in 2013-2015 to assess the current state of levee erosion and attempt to identify associated factors. It was found that 79% of the 584 homogeneous levee segments contained within 148 surveyed reservoirs had block failures and near-vertical slopes. Despite regional winds with preferential southerly and northerly directions, levees of all orientations were damaged by waves. For the surveyed irrigation reservoir levees, soil type, vegetation, inner slope, and berm presence were found to be poor predictor of the state of impairment. The most important variable associated with levee failure was maximum effective fetch length, such that longer fetches were more likely to have block failures and greater loss of top-width.