This usually occurs to the bluff, the primary sand source. The permanent, or temporary, loss of sand cover in the nearshore may expose the underlaying till to erosion. Since the erosion of till contributes very little sand to the littoral transport system, the erosion process is considered irreversible for cohesive coasts. This adjustment process may take years or decades to complete. If the interruption in sediment supply is severe enough, or the sediment shortage cannot be made up, the coastal area may never fully adjust and erosion rates may increase significantly.
Human activities can benefit the sand supply.
At many of the large harbors around the Great Lakes, the adverse effect of the large navigation structures on the sand supply has, at least for the past decade or so, been mitigated by the beach nourishment programs at those harbors. Beach nourishment reintroduces sand into the littoral transport system that has been blocked by the navigation structures, thus maintaining a balance in the sand supply. Return to the Table of Contents Erosion and Recession. The terms erosion and recession are often used interchangeably. However, recession is the landward movement of a feature, such as an elevation contour or the bluff or dune crest, while erosion is the wearing away of land.