Laboratory testing of a model floating wave barrier for reducing wave-driven erosion in on-farm storage reservoirs

Authors: ROSSELL, WILLIAM - University Of Mississippi; OZEREN, YAVUZ - University Of Mississippi; WREN, DANIEL - US Department Of Agriculture (USDA)

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/16/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: NA

Technical Abstract: Dependence of the Mississippi Delta region agricultural industry on groundwater resources has been shown to be unsustainable, as evidenced in the extent of groundwater table decline in the Mississippi River Valley. To reduce the demand on groundwater resources, on-farm storage (OFS) reservoirs may be used to collect and manage irrigation water. Due to the relatively flat landscape and lack of forested areas in the region, these reservoirs are subject to largely unabated winds, and the surrounding embankments of OFS reservoirs are routinely damaged by wind-generated waves. This damage, if not mitigated, results in high maintenance costs over time. It is therefore necessary to identify cost-effective methods of protecting these embankments from wave action. Floating wave barriers (i.e. breakwaters) have been shown to effectively reduce wave impact on offshore and coastal structures, and by identifying a simple, cost-effective design with adequate efficacy, the use of a floating breakwater should reduce the frequency of required maintenance associated with the use of OFS reservoirs. In this study, the use of floating pipe breakwater for wave energy reduction was investigated. Specifically, an efficient design for the cable system which restrains the movement of the floating barriers was needed. The proposed breakwater uses common HDPE irrigation pipe moored to the reservoir bottom by steel cables. A model floating breakwater was constructed and tested with a variety of mooring configurations subject to variable wave characteristics in a wave tank at the USDA-ARS National Sedimentation Laboratory. Time-series water surface elevations were recorded, as well as the forces sustained by the mooring cables. Tests were also conducted to track the motions of the floating barrier using photogrammetric methods. Results of these experiments will be discussed, including wave energy reduction for different levels of submersion, performance of the model under different mooring constraints, and the associated movement patterns of the wave barriers. The details of a full-scale floating pipe breakwater for deployment in a working irrigation reservoir will also be discussed.