Traverse stamp sands alter action of waves
HOUGHTON — One little considered but significant impact of stamp sands is the change to shoreline wave action.
At last week’s meeting at the Great Lakes Research Center, Northern Michigan University geology professor Bob Regis explained some of his concerns and research.
Regis is a long-time Traverse Bay resident. Since growing up on the shores, he has seen a significant shift in wave action causing damage to property and shoreline.
“I remember as a kid swimming on natural sand there,” Regis said showing historical photos of the beach before the stamp sands arrived. “It was arguably one of the best beaches in the Keweenaw for swimming and recreational purposes and fishing.”
His family has long owned land on the North side of the harbor, the section currently dealing with the sands.
“You used to be able to walk out 100 meters before you were over your head. It was just such a gentle slope, and now you walk 10 meters out, and you’re way over your head. There’s such a difference in the slope and the gradient,” Regis said.
With the influx of stamp sands, there is more shoreline in front of the properties on the bay. In fact it’s increasing each year. But now the homes and land are flooding, and Regis thinks it is caused by the slope of the sand offshore.
“Waves begin to feel the bottom at about one half of their wavelength, meaning that at 10-foot depth, waves of about 20 feet begin to scour the bottom,” Regis said. “Where did they do that when the beach was a natural sand beach? Well, it was about 150 meters out… that’s where large waves began to scrub the bottom and start to break.”
Things are different with the encroachment of stamp sands. Waves break around 25 feet off shore with little cushion to slow down the wave’s energy.
This sends the water flooding up the beach towards the homes. This was made very clear by the large fall storms of 2017.
“Here the waves made it all the way back into the bog, 150 meters behind people’s residences,” Regis explained. “It caused a lot of damage.”
Not only that, the waves left behind the coarser and heavier stamp sands in the bog and yards.
It’s a very different situation on the south side of the harbor, where the stamp sands haven’t reached. The shoreline vegetation and homes remained relatively unaffected despite being closer the water.
Regis would like to see consideration of beach profile included in future talks of solutions.