Will your dream house be under water during the next flood?
I was recently asked to have a look at a house near Indianapolis to provide a quote to design a renovation for someone who "flips' houses. The potential client had not yet purchased the house, which was owned by a bank. My first instinct was that the site was vulnerable to flooding from the adjacent creek, but my tour guide said he had been assured the site was not in a flood plain. When I toured the house, clues began to pile up that this house had been flooded in the past and the driveway to the garage in back was nowhere to be found, not even a piece of gravel. Before agreeing to take on the project, I raced back to check the Indiana Department of Natural Resources flood plain mapping site. Local GIS topography data showed the house front yard was two feet below flooding elevation!
I declined the project and directed the potential owner to look at the flood map. The problem with these maps is that they are probably not reflecting the changing climate in the 21st Century and the impacts of continuing development in flood plains and increased stormwater runoff from more impervious surfaces. When evaluating a site for resilience, consider the 500-year flood line, not the 100-year flood line and get as high as you can above that. Those lines are changing. Even if your site is above flood elevation, look at your access routes to make sure that you have at least one way out during a flood event.