Just 2% of land would be enough to protect half of inhabited flood zones

Preserving even 5% of Canada’s watersheds – about 2% of the country’s land – would help protect more than half of inhabited flood zones, a study finds. These natural solutions are neglected, but would benefit from being integrated into national adaptation strategies, according to its main author.

The role tampon natural ecosystems to combat flooding is not new.

However, this study filling in the gaps by defining geographic areas to prioritize for these adaptation strategies, as explained by Matthew Mitchell, assistant professor in the Department of Forest Resource Management at the University of British Columbia.

The study’s lead author himself was surprised to discover that such a small portion of watersheds, representing the equivalent of 2% of Canadian land, can be used to protect so much agricultural land and infrastructure. .

We often underestimate these natural spaces. It’s difficult to make connections and understand that plant ecosystems hundreds of kilometers upstream are beneficial to us.

Large urban centers affected

To achieve these results, he and his team modeled the potential for water retention upstream of watersheds, as well as the development of urban and agricultural areas downstream. By linking the two, they were able to determine which sectors would be most valuable to protect for the greatest benefit.

Result: 5% of watersheds can protect 54% of built flood zones and 74% of agricultural zones in the country, according to the study (New window)published in the journal Ecosystem Services.

These watersheds are located upstream of geographic areas that serve 10% of the Canadian population directly and 56% indirectly, according to the results.

Matthew Mitchell explains that the watersheds of British Columbia’s Fraser Valley, as well as those of southeastern Ontario and Quebec, should receive more policy attention because these regions are exposed to high precipitation, in addition to being very populated.

He advocates protecting existing natural ecosystems, but also restoring as many as possible those that have been destroyed in urbanization.

Part of the Prairies also contains watersheds deemed priority, given the scale of the targeted agricultural operations, according to the researcher.

Tamsin Lyle, a flood engineer in Vancouver, is not surprised by the study’s results and the geographic areas to prioritize. The risk in floods is not that there is water. It’s water that’s superimposed on exposure, of people and communities, and the fact that these communities are vulnerable to watershe explains.

The results of this study give governments the opportunity to understand return on investments to the protection and restoration of natural ecosystems, according to her. That [leur] also gives a way to prioritize them and know where we should make investments firstsays Tamsin Lyle.

A recognized role, but too little exploited

Tamsin Lyle laments that the benefits of natural areas are so well known for coping with flooding, but remain so little used in government adaptation strategies.

We have control over our use of the land. We have things we can do, it’s an opportunity to act on climate change.

Because of anthropogenic global warming, floods are expected to be more serious and more frequent, as are forest fires, which destroy the forest cover.

While it may seem difficult to act in the face of this reality, communities and governments have room for maneuver, recalls Tasmin Lyle. The preservation of natural spaces provides a return of profits in the long term, she maintains.