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Title: Wave-induced erosion of soil embankment in in laboratory flume

item OZEREN, YAVUZ - University Of Mississippi
item Wren, Daniel
item Reba, Michele

Submitted to: Journal of Hydraulic Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2020
Publication Date: 2/11/2021
Citation: Ozeren, Y., Wren, D.G., Reba, M.L. 2021. Wave-induced erosion of soil embankment in in laboratory flume. Journal of Hydraulic Engineering. 147:04021011.

Interpretive Summary: On-farm irrigation reservoirs are commonly used to reduce dependence on limited groundwater resources in the Mississippi river alluvial floodplain, particularly in the state of Arkansas. A typical size for the reservoirs is approximately 10 Ha, with a maximum fetch of approximately 500-600 meters. Typically constructed using local soils, unprotected earthen embankments are subjected to rapid erosion and retreat due to wind generated waves and surface runoff, which creates additional maintenance cost for producers. Farmers who rely on irrigation reservoirs need an economic basis for selecting a protection method for vulnerable embankments. A review of the literature did not yield a viable approach for relating wave properties to the rate of erosion or retreat of an earthen embankment, leaving the question of how much a reduction in wave height will add to the life space of an embankment. The objective of this manuscript is to describe the results of laboratory experiments on cohesive embankment erosion, including the development of theoretical approach, based on the experimental data, for relating wave characteristics to the erosion of an earthen embankment made from cohesive soil. The results of the study provide a means for estimating how much longer an unprotected levee will last, based on a reduction in wave height.

Technical Abstract: Irrigation reservoirs are widely used in the Mississippi River alluvial floodplain to supplement limited groundwater resources. Constructed using local soils that are often low in clay content, the earthen embankments of these reservoirs are susceptible to wave erosion. In this study, laboratory experiments were performed to quantify wave induced erosion and retreat of the cohesive embankments of shallow reservoirs. A model erodible embankment was installed in a laboratory wave tank using a standardized packing procedure. The model embankment was exposed to wave action for up to 48 hours, and its morphological evolution under the action of regular waves was monitored. An analytical model was developed to predict the bank retreat rate. The analytical solution was validated with the experimental measurements. Relationships were established between embankment erosion, edge retreat rates, and incident wave height. The waves quickly undercut the upper part of the embankment face and formed a scarp, which retreated in discrete slump failures until an equilibrium profile was established. Eroded volume was linearly related to retreat distance for the conditions of this study. A unified empirical relationship was established for erosion and retreat rates, which depended only on wave height for the tested embankment characteristics.