Mapping Coastal Wetland Change Based on Lake Level Fluctuation on Lake Ontario

Using an integrated digital elevation and bathymetry model of Lake Ontario and historic lake level data from 1860 to present, coastal areas of periodic inundation were identified to generate, by association, an estimate of coastal wetland change due to lake level control. Pre and post Robert Morris Dam models were constructed to help determine the reduction of lake surface area when the dam started to control the extreme highs and lows. The model creates annual high and low lake surface coverages. The goal of this study is to create a baseline analysis and methodology for future studies on wetland change on Lake Ontario. Results of this study indicate an average change in lake surface area of 123 square kilometers between pre and post dam periods, based on 148 annual calculations of the high and low water levels for each year. Lake levels are generally stabilized after the dam installation, with considerably less fluctuation at the lowest lake levels, compared to pre dam fluctuations. Spatial results were limited by the currently available 3-second (90m) per pixel resolution of the combined bathymetry and elevation data, which renders general results that mask shoreline details and seem to over estimate inundation. As higher resolution data become available in the next few years, such as LiDAR and SONAR, the methodology of the model should be adaptable, resulting in more accurate models for predicting areas of inundation, exposure, and potential wetland change due to alterations of historic lake level variability