Global warming could impact Great Lakes beaches – Great Lakes Now

This article has been republished here with permission from Echo of the Great Lakes.

By Yue Jiang, Echo of the Great Lakes

According to an expert from the University of Guelph, global warming will produce more frequent heavy precipitation events in the upper Great Lakes.

Rather than lowering average water levels as previously assumed, it is possible that the average will rise due to more rainfall, which will tighten the beach area, said Professor Emeritus Robin Davidson-Arnott of the Department of Geography, Environment and Geomatics.

Davidson-Arnott said water levels are determined by the inlets and outlets of each individual lake basin.

In the upper Great Lakes, including Lake Superior, inputs come from precipitation on a lake itself and from rivers flowing into it.

The outputs are evaporation and outflow from the lake, which are also key drivers of water levels in the lower Great Lakes.

“For all the lower lakes, we need to include the outflows from the upper lakes,” Davidson-Arnott said. “If it’s particularly wet in Lake Superior, it will increase flow in Lakes Huron and Michigan, so water levels will rise.”

“When I first started looking at this, for example 25 years ago, the predictions were that global warming would lead to increased evaporation from basins (lakes). Therefore, we could expect levels lakes in, say, Lake Superior, Lake Michigan and Lake Huron are shrinking” and that global warming would lead to an overall decline in lake levels, Davidson-Arnott said.

Over the past 20 years, the computer simulation models he uses to predict the impact of global warming on storm and precipitation frequency have been developed.

“We have increased certainty in the predictions we get, so if we know what’s likely to happen, then we can do a better job of producing plans to adapt to those changes,” Davidson-Arnott said.

Predicting water levels is necessary, as their rise and fall shapes the network of sandy beaches where people go for recreation.

A sand beach system means that the amount of sand brought in by the waves is equal to the amount that could be washed offshore.

“Once the water reaches its maximum level, the waves bring the sand ashore and the beach widens again. Although it actually widens in many places, the beach will become very narrow, limiting the width of the people’s access area,” he said.

He described some of the impacts rising water levels would have on beach systems, which he described in a study published in the Journal of Great Lakes Research.

For example, he says, “in some areas where you have parks, they may have built walkways and steps down to the beach. These tend to be destroyed in storms when the water level rises, so we need to rebuild this infrastructure.

There have been an increased number of projects aimed at protecting the coastline from higher water levels, said Madeline Magee, Great Lakes and Mississippi Monitoring Coordinator with the Wisconsin Department of Natural Resources.

She said most of the projects done by her office were done holistically instead of just shielding the shoreline.

This involved “looking at what species are planted near and around the beach, how people use the beach, and what kind of trails help recreative people get to the beach. That’s kind of the approach we’ve taken. ” she says.

The Wisconsin DNR is proposing a waiver to designate a pilot horse trail in the Nipissing Swamp State Natural Area in Point Beach State Forest on Lake Michigan. It aims not only to assess public perceptions, but also the risk that horses bring invasive species.

There are natural areas, like state parks, where his team doesn’t have to do much, Magee said.

In such cases, there is no huge net change because erosion occurs during periods of high water levels, she said, but new sediment will accumulate in these areas in five or six years when water levels recede.

However, this approach depends on the infrastructure that is around, the measures that could be put in place and the extent of the buffer zone along the coastline.

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