In my neck of the woods we’ve been dealing with some pretty severe spring flooding. And as is often the case, existing flood maps are not up to handling the new normal imposed by climate change. Sainte-Marthe-sur-le-Lac, a community near Montreal, was hit hard by flooding this spring, but only two of the 800 flooded homes were in current maps’ flood zones. This isn’t an new situation; we had similar floods in 2017. Back then, CBC News reported that Montreal-area flood maps’ 20- and 100-year floodplains were exceeded by the then-current flood extent.
Fast forward to this spring. The flood maps for Montreal-area municipalities have been updated—they’re now based on LIDAR data from 2014 onward—but have not yet made public: they’ve yet to be approved by the municipalities or adopted by the province; nonetheless they’ve been put to use during the recent emergency. On the new maps, some 1,500 homes in Sainte-Marthe are part of the flood zone.