McLain erosion likely to continue
HANCOCK TOWNSHIP — The combination of high water and strong storms chipping away at McLain State Park may show Lake Superior’s water level cycle and mean bad news for the bluff.
Erosion of shoreline is occurring throughout the Great Lakes and will continue. At McLain, the park chose to pull back from the water, placing campsites and buildings further inland in anticipation of continued shoreline loss.
Coming out of 10 to 15 years of low water levels, the change was unexpected for some, but James Selegean out of the Detroit Army Corps of Engineers Great Lakes Hydraulics and Hydrology Office believes the shifts are cyclical.
“Because the cycle is kind of long and humans don’t live in one place long enough to see these cycles go up and down… Every time the lakes come up everybody thinks there’s something unusual going on that there’s something not normal going,” Selegean said.
This becomes an issue when people build homes, roads and businesses based on low levels of erosion only to be caught by surprise.
“Erosion on the great lakes has been happening since the glaciers left 10,000 years ago and it will continue to happen,” he said.
Great Lake Research Center Director Guy Meadows sees a similar pattern with the lakes at the high water level point of the 15-20-year shift and producing more intense storms. The resulting high-water waves can have 25 percent more energy. Though the cycle of low and high water levels is natural, Meadows thinks greater variability in levels could become the norm. Meaning more dramatic low levels as well as high levels.
This spells bad news for McLain.
“The high water level changes the place and allows the waves to work right against the base of the bluff and the waves are bigger and more frequent than they are during low water years and unfortunately we are seeing both of those events happen along McLain,” he explained.
The Great Lakes are new geological features in the life of the earth with a natural tendency to eat away shoreline due to the depth and steep formation. Meaning McLain probably won’t be getting that shoreline back, at least not the way it was.
During low water years, sand can return but it’s more prone to erosion at that point.
“It builds back with loosely consolidated kind of sugar sand that we know and love here in the Great Lakes on our beaches. What has eroded away is material that has been packed and undisturbed since the last glacial retreats some 8 to 12 thousand years ago so it is much more resistant,” Meadows said.
Sand and sediment that is eroded is carried out to deep waters where it is unable to return or pushed down the shoreline.
Tomorrow: Erosion mitigation techniques and challenges.