Bluffs, Erosion and Climate Change
When it comes to what people can do to deal with climate change, it boils down to two approaches: mitigation and adaptation. Mitigation is about reducing greenhouse gas emissions to the point where they no longer negatively pose a threat to our climate. Adaptation is about people adapting to changing conditions, and developing coping strategies. In the absence of strong leadership to work toward climate mitigation (reducing ‘greenhouse gas’ emissions), local communities are wise to plan adaptation measures to deal with the results of ensuing climate variability. The Great Lakes region needs to prepare for important changes that will affect coastal areas. This article describes one specific coastal ecosystem that the Coastal Centre has recently researched to better understand what to expect, and how best to plan ahead.
In 2014, the Coastal Centre initiated a research project looking at the impacts of climate change to Lake Huron shorelines – specifically bluffs and gullies. This research study looked at what influence climate variability will have on this type of shoreline, and what communities should be prepared for. Bluffs and gullies were of particular research interest because of their vulnerabilities to erosion and slope de-stabilization.
The study looked at historical trends in precipitation, temperature, lake levels, ice patterns and erosion history to gain some insight into how these factors are projected to change, and how this will affect bluff and gully conditions.
Overall precipitation in the lake basin is expected to increase by 12%, but the pattern of rain and snow is expected to reduce in frequency but increase in intensity. That means that, while we may not get as many rain or snow storms, their intensity will increase. Heavier, intense rain storms will create higher runoff from the land, with a corresponding increase in erosive force.
The study also looked at temperature trends that suggested an overall trend toward higher average temperatures. This could mean milder winters, which could affect the timing of when ice forms in fall and leaves in spring. Ice formation along the shore protects the shore from erosion, particularly during the fall/winter storm season. Ice formation later in the season could expose shorelines to increased erosion, since this is typically the period of year when the greatest wave energy is present.
Our winters are anticipated to be milder, meaning that those nostalgic winters where it snows in November and stays until April, may be less frequent. More common will be winters with multiple freeze-thaw cycles: snow-melt-runoff-repeat. This will be problematic in bluff areas for a couple of reasons. First, multiple snow melt and runoff events will increase overland surface runoff causing erosion. Second, repeated freezing and thawing can be destabilizing to slopes, as water gets into deep soil cracks, freezes and expands, prying the soil mass further apart, and weakening the structure of the soil
The report also suggests that how people interact with and manage the lakeshore can and will influence the degree of bluff and gully erosion. Vegetation is fundamental to slowing erosion and providing slope stability. There are many instances where people have removed vegetation far in excess of what should have been removed (often to get a better view of the lake), and this has unfortunately contributed to increasing the erosion process in these areas. This study helps to underscore how such activities will be much riskier under the changing climate.
While the process of erosion is a fact of life along the lakeshore, the changing climate may present us with greater erosion in many locations. Some of this erosion is part of a long term recession process, largely unstoppable in practical and ecological terms. On the other hand, there are areas where the erosion process may be slowed, simply by following some stewardship practices aimed at prevention:
- Care for the natural vegetation on bluffs and gullies.
- If you use a septic system, water conservation is important in order to minimize the contribution of water to the bluff area. Too much water to the bluff adds substantial weight to the top of the slope making it top heavy, and the effluent can lubricate the soil particles contributing to slope failures.
- Managing storm water runoff in a manner that prevents unnecessary erosion and controls the water flow from top of bluff to the beach will help to prevent gullying and slope failures.
Planning for what’s ahead, and being able to adapt to changing conditions should help local communities better cope with erosion risk in the future. As history informs us, bluff erosion is often met with panicked reaction, where poor and costly choices sometimes get made. ’Plan for the worst, and hope for the best’ – wise words of our elders. Perhaps this research will help inform the path forward in living with the new realities of our coast.
[Article by Geoff Peach, Coastal Resources Manager. Based on the science report by Jasmine Bhurji, Coastal Geohazard Intern with the Coastal Centre, funded through Environment Canada’s Science Horizons Youth Internship Program.]
View the full report here
More on Bluff Stewardship
Keeping Watch
The Coastal Centre’s “Coast Watchers” volunteer monitoring program is gearing up for another year of information collection on lake conditions. This citizen science program relies on volunteers who dedicate some of their time to collect observational and/or measured data, and report this information back to the Coastal Centre. The information from all Coast Watchers is analyzed and presented in an annual report that is posted on our website.
Coast Watchers are selected from volunters who live along the Lake Huron coastline from Sarnia to Tobermory. We currently have gaps in the Grand Bend to Sarnia area. Anyone wishing to participate in the program from this area should contact Karen Alexander, Education & Outreach Coordinator at the Coastal Centre’s Goderich office (226) 421-3029. A training webinar is scheduled for April 22nd. Contact Karen to register by phone or email: karen.alexander@lakehuron.on.ca
For more information on Coast Watchers, click here.
Speaking of volunteers, Stewardship Grey Bruce is looking for interested people to become part of the Piping Plover Guardian program. For the past eight years on Lake Huron, the endangered Piping Plover has successfully nested on beaches at Wasaga Beach, Sauble Beach, Oliphant’s Sandy Bay and Port Elgin’s main beach. Volunteers are needed to monitor anticipated nesting sites.
Orientation sessions for volunteers will be held on April 30 (2 pm), & June 4 (7 pm) at Sauble Beach’s Community Centre.
To sign up,email: volunteer@ploverlover.com
Help give these little birds a fighting chance.
Is There Anything Better?
Ah, Spring on Lake Huron – is there anything better? Well, except for maybe Summer on Lake Huron. And Fall can be pretty nice too. The point is that, it’s always great on Lake Huron.
Celebrate Lake Huron’s greatness with a donation to an organization that is dedicated to helping our lake: The Lake Huron Centre for Coastal Conservation. An organization for ALL seasons.
To make a donation click here.
