Flooding is one of the most dangerous situations for most people. Most people think that flooding can only occur around large rivers or at the ocean but there are many factors that can cause flash floods in areas that normally are dry during heavy rains.
For this reason the federal government has performed studies of flood prone areas and assigned them X Zone Information. This data can be used by a number of people including your building official, insurance companies, builders and you.
One of the largest contributing factors to inland flooding is land development. Although precautions are suppose to be taken whenever a new housing development or shopping mall is built to reduce the possibility of water runoff accumulating there are always situations where drain-way blockages occur which cause backups of water.
Another situation is when rainfall rates are too high / fast for the ground to absorb the water.
But even in normal situations there are a large percentage of homes that are built in areas that are prone to 50 or 100 year floods. This means that you can expect some type of serious flood in your area during your lifetime.
X Heights and Flood Zone Maps
The USDA Soil Conservation Service along with a number of other agencies work with state and local officials to design maps of flood zones. Flood Zone Maps show the X Height or the possible level of water during a 100 year period that could be expected in that area.
If you have seen a typographic map that shows circular patterns with elevations used to describe hills and mountains then you know how to read these maps. If not they are pretty easy to read you just find your location and find the x height nearest your location..
X heights are suppose to be used in building new homes and other things like roadways and runoff catchments. Unfortunately when an X height is established that height is taking into consideration the amount of paved roads, driveways, rooftops on homes and shopping center parking lots.
[Insurance companies and building officials will place specific requirements on new homes being built in Flood Zone areas. Specifically you must elevate the buildings livable first floor above the X Height by 1 foot or more. You must also place utility services Gas, Electric, Water services above this height.]
Once development begins in the area the x heights often need to be redesigned but often they are not re-engineered for many years. If your area is prone to floods you can expect that any large development project in your area will contribute hundreds of thousands or millions of gallons of water to the problem and you should also know that the problem does not have to be immediately near you. If development occurs up hill from your location even a mile or a few miles away you may find yourself under water when normally in years past you never had a problem.
Unfortunately post litigation is almost impossible when a development project causes intermittent flooding. And if your home does not have flood insurance you may find that you have lost everything and have little recourse. So you should always make note of any projects that are happening in your area and make sure they don’t cause you problems later
For more information and to check the Flood Zone Maps in your area goto Fema’s Website. https://hazards.fema.gov/femaportal/wps/portal