I have heard politicians and people of authority express what a 200 year floodplain means and it drives me crazy when they explain it incorrectly. A 200 year floodplain does not mean the occurrence will only occur every 200 years. A 200 year flood plain is a way of describing the probability of a flood event. For clarity, it should more likely be named a “200 year probability of return period of a flood”.

Return period is calculated as 1 divided by the annual exceedance probability (AEP). For example, for a 100-year return period storm event, there is a 1/100=0.01=1% probability in any given year that the event or a larger event will occur. Return period is not the strict frequency of an event, i.e., if a 100-year return period event occurs this year, there is still a 1% probability that it will occur next year as well. For a 200-year return period there is a ½% chance every year that flooding will happen at that elevation.

In the Comox Valley there have been several floodplain reports. The Oyster River study in 1984, Putledge, Tsolum and Courtenay River study in 1991 and as recent as 2021 Final report on Coastal Flooding in the Comox Valley Click to View Report.

It is important to remember where we live. Much of Vancouver Island and West Coast of British Columbia is a mountain range with several rivers running down mountain sides to the ocean. Events such as intense rainstorms, rapid snow melts, large windstorms and extraordinarily high tides can cause flooding in many places. 

It is important to understand your insurance policy, understand where your home is in regard to a return cycle/floodplain and how you can best mitigate any risk. This could be by landscaping to include water absorption, flood gates and water catchment areas. Ensuring the ground above you can absorb water and the ground below you can move water away from you. This spring when you are gardening, consider extraordinary water events and what you can do to protect your home.