Erosion and Recession of Beach-Bluff System of Low Fine Content Due to Wave and Surge Actions

Coastal bluffs are at the intersection of land and seas. Thus, their failures and recessions are controlled by both land- and sea-based activities. Bluff recession imposes risks to structures and infrastructures and has environmental and economic consequences. Hence, it is critical to understand various processes influencing bluffs behavior, necessary for developing predicting tools and methods for future bluff recessions. We developed an experimental campaign to study the effects of fine content on the erosion and failure processes of predominantly sandy bluffs, bluffs that are composed of mostly sand and little fine contents. Bluff models of various soil properties underwent wave and surge actions in a wave flume. The responses of the bluffs to those "sea-based" activities were recorded and analyzed using image processing techniques. Then, the rates of beach erosion, and undercutting and recession of the bluffs were assessed against the fine content of bluff material. Our observations and analyses highlight the effects of fine content on the erosion of foreshore and instability and recession of bluffs.