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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #350461

Research Project: Managing Water and Sediment Movement in Agricultural Watersheds

Location: Watershed Physical Processes Research

Title: Wave erosion of cohesive and non-cohesive embankments: Laboratory experiments

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

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/20/2018
Publication Date: 9/5/2018
Citation: Ozeren, Y., Wren, D.G. 2018. Wave erosion of cohesive and non-cohesive embankments: Laboratory experiments. River Flow 2018, International Conference on Fluvial Hydraulics IAHR. Lyon, France. September 5-8, 2018. 1-8 pp.

Interpretive Summary: Irrigation reservoirs are 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. Unprotected earthen embankments, which are usually made of local soils, display rapid erosion and retreat due to wind generated waves and surface runoff, creating additional 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. The objective of this manuscript is to describe the results of laboratory experiments on cohesive and non-cohesive embankment erosion. The non-cohesive embankment was made from plastic beads and will be used to help isolate the effects of soil characteristics. The information will be used for relating wave characteristics to the erosion of an earthen embankments. The results of the study help to provide a means for estimating how much longer an unprotected levee will last, based on a reduction in wave height.

Technical Abstract: Laboratory experiments were carried out in a wave tank to investigate the wave induced beach profile evolution and scarp recession on cohesive and non-cohesive model embankments. The cohesive embankment was constructed using a natural soil mixture, and the non-cohesive embankment was constructed using cylindrical shaped PET pellets of uniform size. A standardized packing procedure was used to for both cohesive and non-cohesive embankments. The shoreward face slope of the embankment was approximately 30 degrees. The morphological evolution of the embankment was monitored using water level sensors and a time-lapse camera. Waves quickly eroded the bank face near the free surface and formed a scarp (Figure 1). The scarp of the cohesive embankment retreated by a series of wave undercutting and slump failures. An empirical relationship between incident wave height and was established for embankment erosion and edge retreat rates was established for the tested conditions, which depended only on the incident wave height for the tested embankment characteristics. The measured beach profiles were compared with the developed analytical solution.