Flash Floods with Rainfall
Flash floods are usually caused by excessive rainfall that occurs in a short period of time. They are dangerous because they are powerful, speedy and unpredictable. They can happen with little or no warning at all.
Densely populated areas are at a high risk for flash floods. Buildings, roads and parking lots in the area reduce the amount of rain absorbed by the ground. Sometimes streams that run through cities are routed into storm drains. These drains can become overwhelmed and flash flooding can result.
Areas near rivers are also at risk for flash flooding. If levees along rivers fail, flash flooding can result. In 2005, New Orleans experienced devastating floods during Hurricane Katrina due to the failure of the levees.
Dam failures and rapid runoff from mountains and steep hills can also cause flash flooding. When water is falling faster than the ground can absorb it, a dangerous, flooding condition can result.
No area is really immune to flash flooding. During storms it is important to pay attention to weather watches and warnings and take the necessary precautions. Always listen to forecasters and be prepared with a plan in place just in case a flash flooding situation arises!