MULTI-YEAR LAKE LEVEL VARIATION CONTROLS BARRIER SPIT REGRESSION AND TRANSGRESSION AT SHELDON MARSH LAKE ERIE, OHIO

Lake Erie beaches respond to storm events, seasonal and multi-year lake level variation, and sediment supply. Regression and transgression of the shoreline impacts habitat, recreation, and infrastructure. This study examines changes to the barrier spit at Sheldon Marsh State Nature Preserve, located in Western Lake Erie. Prior studies have shown this barrier to be sediment supply limited and the barrier position between 1937 and 2003 to be sensitive to changes in lake level variation. Our study examines changes to the barrier spit depositional sub-environments since 2003 using aerial photography, on-the-ground GPS mapping, and topographic beach profiles collected every other year. Between 1999 and 2016, the average monthly Lake Erie level was similar to or below the 106-year long-term average. During this seventeen-year period of lower lake level, the dune/berm boundary regressed up to 27 m, and dune forest cover increased. Between 2016 and 2020, the lake level rose to record high water in 2019. Within the 106-year-long record, eight of the top ten highest monthly average water levels occurred in 2019 or 2020. During this period of rising lake level, the dune/berm boundary transgressed up to 16 m. Since 2020, the lake level has fallen, and the dune/berm boundary remains largely unchanged except for small areas of newly vegetated dune ramp. This study reveals that the seventeen-year period of low lake level allowed for an extensive dune to develop. This dune functioned as a buffer to erosion when the lake reached record heights in 2019/2020. This recent limited transgression contrasts with the extensive erosion and transgression that occurred in the late 1980s. The late 1980s transgression was preceded by fourteen years of higher than average lake level and lacked the conditions for dune development. Our study shows that multi-year lake level variation is an important influence on dune development and the barrier's ability to establish a buffer against erosion.