The New Braunfels edition of Community Impact Newspaper recently explored ongoing flood initiatives in the city. Often, flooding events are referred to as 50- or 100-year floods. What does that mean?
Importantly, the terms do not mean that it is a flood that will happen every 50 or 100 years. Instead it refers to the likelihood that a flood will happen.
So a 50-year flood has a 2 percent chance of happening in any given year, and a 100-year flood is a flood that has a 1 percent chance of happening in any given year.
For reference, officials have estimated that the Memorial Day floods of 2015 were nearly a 200-year flood—an event with a 0.5 percent chance of occurring in a given year.
These calculations are important, particularly when it comes to neighborhoods that are located in flood plains. For example, if a neighborhood sits in a 25-year flood plain, that means it has a 4 percent chance of flooding in any given year.