Figure 4 - 3D Modelization of the Nutashkuan topography and hydrogeology; the blue color represents the St. Lawrence River (left) and Natashquan River (lower horizontal)
What are the enduring benefits of this project?
Soheil Nakhostin: The solution maximizes preservation of the natural environment. The locations of the drainage chambers along Route 138 were strategically selected to avoid excavation work in the community’s residential area; the selection also avoided unnecessary deforestation, especially as vegetation growth is very slow in the region. The use of trench boxes, instead of conventional excavation methods, also minimized tree felling.
The system is cost-effective, built at 1.8 million dollars [CAN] and has proved efficient in protecting the entire community against flooding, as confirmed by piezometric measurements from 2019 to 2021. The 2017 flood resulted in four million dollars [CAN] worth of damages.
The project also brought social benefits for the community. The hiring and training of local workers and the use of local resources contributed to stimulating the economy.
Another benefit was that this project enabled development of a storm drainage system. As the catchment system in this project ensured the efficient drainage of underground water, a storm drainage system based on the same general principle was built in 2020 to lower water levels and redirect stormwater to the river. In the short term, surface water drainage will allow the community’s roads, which are mainly made of gravel, to be paved.
Also significant, as climate change will likely have an increasing impact on variations in different groundwater tables, water experts around the world are increasingly challenged to identify the approach appropriate for each community, enabling the residents to adapt to local conditions.
The innovative solution and design tailored for this community could also provide long-term protection to communities living in areas experiencing similar conditions.