People who have bought home insurance may have seen the term “flood plain” in the policy and wondered what it meant. Generally speaking, homes build on flood plains will be costlier to insure. Living near a waterway is an attractive prospect to many, but it is important to understand the land and the natural processes that work in it. Flood plains can be beneficial, but demand management.
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Definition of Flood Plain
A flood plain is the land from the banks of a river or stream to the walls or rises of land surrounding it. It is flat land, often terraced close to the waterway. The defining characteristic of the land is that it is subject to regular flooding.
Anatomy of a Flood Plain
Flood plains consist of two parts. The first is the main river channel, also called the floodway. Many of these channels are dry through much of the year. In New Mexico, for instance, drivers often see signs as the highway traverses signs that warn them not to cross if there is a flood warning or heavy rainfall. That is because the sandy draws can become raging streams in a matter of minutes, flooding the highway and surrounding land.
The second part is the flood fringe. This is the area that stretches to the valley wall or the rise which defines the flood plain. Some of these fringes are narrow, but some are extremely wide. An article in the online National Geographic Magazine cites the Barotse Flood Plain as an example. It includes the Kalahari Basin which is swampland during the rainy season and becomes part of the Kalahari Desert during the dry season. Narrow fringes are usually found where waterways are fast-moving and have steep banks.
Flood Plain Drawbacks
Some of the obvious negative factors of flood plains are that they are risky places to locate homes and businesses and that they may be expensive to manage. According to the United States Geological Service, damage and loss to floodplain areas average more than $2 billion a year. Additionally, each year 100 people die in floods. People who locate homes on flood plains are always at risk, which is why insurance costs more for these properties. Some areas are prone to annual flooding, and some areas have a history of “fifty-year” or “hundred-year” floods. Cities locating along waterways in flood plains generally must plan around the prospect of flooding. The White River, which flows through southern Missouri, often floods the fountains and walkways of the Branson Landing shopping area which includes many apartments.
Advantages
Flood plains do have some beneficial aspects. The soil is usually fertile, and the land flat, making them wonderful places to grow crops. Cities located along waterways in flood plains use the flat areas to build infrastructure such as highways. Merchandise shipped on the rivers can be easily transferred to land transportation. Areas closest to the floodways are called “green spaces” and may include parks and walkways. Hotels often locate along the floodway as well. Cities may restrict the building of residential communities near the water because they are harder to evacuate during floods.
Flood plains are part of the landscape, and their shape and size tell geologists much about their history. Understanding the cycle of the plain can help planners manage its use. Locating in a floodplain, however, can be a risky and expensive venture.