Dude, Where's My Beach?
By Geoff Peach, Lake Huron Centre for Coastal Conservation
As people made their way to the beach last summer, some arrived wondering where the beach had gone. Particularly in dune areas, the shoreline appeared to be overtaken with dune grasses. What actually happened was a confluence of natural processes.
After Lake Huron’s last high lake level in 1997, water levels dropped dramatically in 1998 and stayed well below average for nearly a decade and a half. With the low levels came wide expansive beaches. These open sandy beaches were prone to wind erosion, and sand was being blown and deposited into the dunes as part of their natural re-building process.
Marram grass, a dominant dune grass on Lake Huron beaches, has its growth rate stimulated by sand burial. The wide open beaches created an opportunity for the grass to grow lakeward. That’s a good thing. If it didn’t grow lakeward, causing the dune to grow wider, the dune would instead grow higher and people would be living beside a vertical wall of sand. Most dunes instead grew wider, toward the lake, building up the sand reserve that would help protect the shore and maintain good quality beaches once higher lake levels returned.
Well, since that extreme low lake level of 2013, lake levels have rebounded impressively, having risen nearly a metre. The wet autumn, winter, and spring contributed to levels continuing to rise well into 2015. Despite the warm El Niño winter of 2016, levels have remained steady, even though there was a lack of ice cover.
El Niño is the warm phase of a complex weather pattern coming out of changing ocean temperatures. Lake Huron has been warmer than some years but the air above it has been warmer too and this leads to lower rates of evaporation. There is more evaporation when cold Arctic air masses flow over a warm lake. There weren’t any significant cold air masses either during the autumn of 2015, or the winter of 2015-2016. In addition, a wet December in 2015 slowed the seasonal decline in lake water levels.
What changing lake levels have meant for some cottagers has been alarm at a perceived loss of beach. The dunes that had grown lakeward for the past number of years were being met with a rising shoreline, leaving little open sand to lay a beach towel. But Mother Nature eventually puts things right. Open beaches are open because of an important process: storm waves.
The reason we have open beaches at all is because of storm wave activity. If that were not the case, we would have forests growing right up to the water’s edge.
Fluctuating lake levels are part of the magic of living along the coast. They’re always changing, and always unpredictable. The dramatic changes experienced recently underscore our need to be adaptable and flexible to the natural rhythms of the lake. There is a period of re-adjustment as narrowing beaches are widened by storm waves. With higher lake levels, dunes will erode, providing a needed supply of sand to your beach.
How to help protect your beach
How can you aid long-term protection of your beach?
- Leave native dune vegetation to perform its role. The vegetation and root structure provides some resistance to erosion, and allows for a gradual and sustainable exchange of sand between the dunes and the beach. Removing dune vegetation can accelerate erosion and alter the natural balance, causing beaches to deteriorate.
- Hardened structures, like seawalls, revetments and groynes can disrupt sand movement and diminish the amount of sand available to the beach. Avoid hardened structures in beach and dune areas (and most coastal areas, for that matter).
- Motorized vehicles, like all-terrain vehicles, can be very destructive to dunes. Use these vehicles on roadways and designated pathways away from the beach.
Monthly updates on lake levels are available through Environment and Climate Change Canada’s Level News available on their website. For more information on water levels, beach and dune stewardship, and other lake-related issues, you can contact the Lake Huron Centre for Coastal Conservation at 226-421-3029 or visit the website at www.lakehuron.ca.
How You Can Help
- Never toss cigarette butts on the ground.
- Minimize your ecological footprint by using a beach ashtray.
- Never leave plastic litter, such as water bottles, on beaches.
- Plan or take part in a Great Canadian Shoreline Cleanup in your community.