Sometimes it can be a challenge to grasp how natural events are changing over time. We often look at the mountains here in Vancouver and reflect on how “the skiing was so much better 20 years ago!” or we comment on how “summers have never been hotter!”, but these types of anecdotes are frequently tossed around without much reference to real data.
In an effort to more deeply understand the current threat posed by flooding here in Canada, we decided to take a look at our past. We asked the question: Has flood occurrence in Canada increased over the past 100 years? And if so, by how much? Luckily an appropriate dataset already existed, in the form of the federal government’s Canadian Disaster Database or CDD. The methodology used to populate this dataset is unclear and inconsistent, and should be reviewed. However, it is the only public dataset in Canada that provides information on flood damages. As described on the CDD website,
“the CDD tracks ‘significant disaster events’ which conform to the Emergency Management Framework for Canada definition of a “disaster” and meet one or more of the following criteria:
- 10 or more people killed
- 100 or more people affected/injured/infected/evacuated or homeless
- an appeal for national/international assistance
- historical significance
- significant damage/interruption of normal processes such that the community affected cannot recover on its own”
This dataset provides us with information on major flood events, however it does not let us visualize the data in a geospatial and temporal context. In order to address this gap, we georeferenced the data and used the excellent tool CartoDB to visualize it over time. With this visualization, we immediately identified a powerful trend. As you can see below, the data clearly shows that flood occurrence has increased over the past 100 years, going from 3 significant floods between 1900-1909 to 57 between 1990-1999. This is due to many factors, from the lack of data, to the number of people living in floodplains across the country. Regardless, the take home message is that damaging floods are becoming more frequent, and that they happen somewhere in the country every year.
Recognizing that the frequency of flood events is increasing over time is important when allocating resources to deal with them. We cannot expect to approach flood management with the same toolkit we used 50 years ago. As flood frequency and severity increase, so must our capacity to reduce our risk.
We hope to keep working with this dataset to help visualise and inform. If you have any ideas on how you’d like us to next use the data – we have a few of our own – please let us know at firstname.lastname@example.org