Erosion of the shores of the St. Lawrence: we must work with nature
While the estuary and the Gulf of St. Lawrence are facing a lack of oxygen, the shores of the river are eroding, which has direct consequences on the surrounding communities, as well as local ecosystems. Here is an analysis by Jacob Stolle and Damien Pham-Van-Bang, professors at the National Institute for Scientific Research (INRS).
ANALYSIS – The shores of the St. Lawrence River are eroding. This has an impact on infrastructure, the economy and the well-being of the inhabitants. It exposes communities to flooding, and can destroy local ecosystems.
Under the threat of climate catastrophe, careful consideration is needed to enable adaptation to a changing climate in the St. Lawrence.< /p>
In Prince Edward Island, the average rate of erosion is about 0.3 meters per year. In New Brunswick, it is about 0.5 meters per year. However, in Quebec, it is closer to 2 meters per year! And that rate of erosion is expected to increase, as climate change is expected to raise sea levels, bringing water closer to local communities. More and stronger storms will bring larger waves to the coastline and reduced sea ice cover will allow winter storms to gain access to the coastline, land's contact with the sea.
< p>The latest report from the United Nations Intergovernmental Panel on Climate Change (IPCC) calls for transformational adaptation, to completely rethink the way we adapt to climate change to include more sustainable solutions.
As professors of coastal engineering, we work to develop immutable solutions to adapt to climate change in coastal and estuarine environments. We work with communities, businesses and nonprofits to better understand how natural systems can be used to protect coastlines from erosion and flooding.
Traditional approaches are no longer appropriate
In Quebec, approximately 97% of the coastal infrastructure is what we call “hard”. You can see these dykes and breakwaters along the St. Lawrence River, intended to maintain or advance the coastline.
This approach is advocated around the world, since most textbooks of design, research and case studies focus on hard infrastructure; we have been using them for centuries. These types of infrastructure-based adaptation methods are well-established and proven to solve short-term problems without taking up much space on the coast.
The problem with hard infrastructure is that it does not adapt to a changing climate. As such, it often requires maintenance and redevelopment, and can impede the natural evolution of the coastline. This is called the “coastal squeeze”.
Coastal squeeze is particularly problematic when coastlines have been designed to address acute symptoms (such as local flooding) rather than addressing the underlying problem. These limitations, if not properly managed, tend to displace or exacerbate the problem.
Examples of this can be seen in Kamouraska Bay, where land reclamation using levees for agricultural purposes caused the loss of three quarters of the marsh ecosystem over the last century. Additionally, during recent floods, these levees were overcome, trapping salt water on farmland.
Working with nature in a changing climate
The implications of climate change are increasingly evident. Its effects are being felt throughout the St. Lawrence: beaches are eroding and more communities are at risk of flooding. Communities must adapt.
One of the main approaches proposed to adapt to the impacts of climate change is that of “nature-based solutions”. These are coastal protection systems designed to include or mimic natural ecosystems to protect and stabilize the coastline.
An example where nature-based solutions have been applied is that of the park national Forillon, where hard infrastructure protecting a road had disrupted the natural coastal dynamics and caused the loss of the local beach. Researchers worked with the park service to move the road away from the coast and re-vegetate the beach to allow the beach to return naturally.
Another example is the realignment of the Belcher Street seawall in Nova Scotia. For this project, researchers worked with farmers and local governments to relocate a levee so that flood water could be diverted from the local community to areas that once stored water overflowing from the river. Consequently, this also allowed water to return to the floodplain, restoring the local wetland ecosystem.
A multidisciplinary-and-participatory approach
Nature-based solutions are not just about planting and walking away . It is a comprehensive system based on a multidisciplinary and participatory approach that requires working with local ecosystems, communities and economies to find solutions.
This can range from protecting local wetlands to greening hard infrastructure to enhance ecological value, for example to provide habitats for oysters and fish species.
Our research team s business to test solutions co-developed by multidisciplinary groups in our large wave channel. This channel, the largest in North America, allows us to test and optimize solutions and technologies in a controlled environment before they are implemented in the real world.
For example, we are currently investigating how restoring coastal marshes can protect against coastal erosion and reduce wave energy. Using the knowledge gained from the experiments, we can develop guidelines to help engineers incorporate marsh restoration into future projects.
Adapting solutions for the St. Lawrence
In general, the biggest challenge to implementing nature-based solutions is the lack of understanding and guidance regarding their performance in cold regions like Canada. Internationally, several guidelines have recently been published, but they tend to be high level without specific details on how to implement them.
Therefore, as researchers, we must test solutions relevant to the St. Lawrence in the laboratory or in simulation models in order to predict how they will react in reality.
It is also important to places comprehensive, multidisciplinary monitoring programs after the implementation of these solutions to develop a deeper understanding of how they work.
Act now to solve tomorrow's problems
In order to face an uncertain climate future, it is important to aim for proactive planning. Nature-based solutions are complex and time-consuming to develop, as they require an understanding of the whole system. The search for funding for the implementation of pilot projects is also time-consuming. The search for innovative solutions therefore requires time and various skills, especially those of the local community.
Although provincial and federal governments have begun to implement long-term programs that incorporate sustainable solutions, it is important to realize that the banks of the St. Lawrence are eroding now and will continue to erode.
< p>We must act quickly to solve the problems of tomorrow.
Jacob Stolle, Assistant Professor, Coastal and River Hydrodynamics, National Institute for Scientific Research (INRS) and Damien Pham -Van-Bang, Associate Professor, National Institute for Scientific Research (INRS)
This article is republished from The Conversation under a Creative Commons license. Read the original article.