Bank recession and lakebed downcutting; response to changing water levels at Maumee Bay State Park, Ohio
The shore and nearshore area of Maumee Bay, at the western end of Lake Erie, was studied from 1981 to 1990 and this report documents the impact of water levels on bank recession and lakebed downcutting. The shore of Maumee Bay is composed of a low bank of sand-poor glacial lacustrine silt and clay. Three regimes of lake level occurred during this 9-year study. Each regime produced a different character and rate of erosion. During stable lake levels, erosion occurred as bank recession and as nearshore lakebed downcutting. During rising/high lake levels, bank recession continued, but lakebed downcutting slowed except at the new transgressed shoreline. During falling water levels, bank recession all but ceased, the former shoreline became emergent and lakebed downcutting resumed. Over the 9 years of this study, total bank recession averaged about 20 m and nearshore lakebed downcutting averaged about 50 cm. At lower lake levels the visual (from land) erosion ceased and lakebed downcutting became dominant, which continued to deepen the nearshore. Therefore, when higher lake levels return, waves in the deeper water will have an even greater impact on bank recession rates.