Many people live in flood plains and don't realize it. These are hazardous areas near rivers or other bodies of water which may flood if too much water is present. We've all seen many examples of the type of flooding that can occur in these regions. For example, parts of the UK known to be flood plains experienced massive flooding in 2000 and 2001 after heavy rains and devastated hundreds of people. The same happened in 2007 to the Missouri flood plain. Identifying a flood plain and choosing not to live or work in that area can save you an immense amount of money and grief.
Identifying the Area with a Map
Grab a map of the area you suspect to be a flood plain. A topographical map is a good idea, if you know how to read one. These provide detailed information on the terrain and elevation. Otherwise, a map that shows terrain, such as a physical map, will also work. Don't use a political or road map, as these are worthless. It's also best to use a map of the immediate region only, rather than the entire state or country. This way, you will be provided with more detail.
Pinpoint large bodies of water, such as creeks, rivers, lakes and even the ocean if applicable. Make a note of each of these, and examine the terrain on the map near each body of water. Pay particular attention for flat, low-lying areas as these are often flood plains. They may include areas such as beaches, swamps, or a relatively flat valley through which a river meanders. Also look for well-marked banks, or levees, along rivers and lakes. High light, circle or mark these areas on your map for later reference.
To confirm that an area you suspect to be a flood plain is in fact one, you'll need to take a visit there physically. Many clues are often left by floods that will give it away, even if a serious flood hasn't happened within the last decade. Begin your examination by looking at the vegetation. In flood plains, plant matter is often lush. This is due to the rich soil deposits left by flooding, which fertilizes the land and allows plants to grow more healthily. One famous example of this is the Nile River in Egypt, which has supported life for thousands of years through a yearly flooding.
If the soil seems to be very fertile, then take some samples. An incremented method is best, by taking samples at the water's edge, then every 50 to 100 feet or more. Look particularly for soil that seems muddy, full of river silt, shells, sand or even remains of marine life, such as skeletons fossilized in the mud.
A last, but key clue is the presence of an oxbow lake. These are small lakes that curve in the same manner as the curve of the body of water or shoreline. They occur when water is deposited in a gully then becomes trapped there as the water recedes. They may or may not be on a physical map, as they often form only from a recent flood. However, if the region you are examining has one or more oxbow lakes, then it has flooded in the past.
River Bends and Flooding
Certain areas are naturally more susceptible to flooding than others. Building in these areas is unwise. The inner bend of a river is one such example. Rivers naturally tend to meander and alter their course through the landscape, and won't stop because of a house. With the water flowing on three sides of the land, these areas frequently experience the most flooding, even if the rest of the flood plain remains relatively untouched.
Bends are still dangerous if the river is low and the houses are on a bank. Water's erosive nature will gradually sand down the bank, and can knock the ground right out from under you. Houses falling into the river is the tragic culmination of this event.
Many people continue to live and work in an area susceptible to flooding, despite the dangers. While severe floods are generally uncommon, our news archives are filled with plenty of examples of the consequences of living in such a dangerous area. Knowing how to identify a flood plain can help you avoid or prepare for a potential flood.