A flood is defined as an overflow of water that submerges dry land. If the water reaches land that is populated by people, such as a village, it is considered to be a natural disaster. Floods usually occur near large bodies of water, such as a lake or river. When a storm causes the water levels to rise, the water may over flow the boundaries of the river and lake and spread to areas of land that are otherwise dry. Levees or dams may be built on rivers or lakes in order to prevent floods from happening, but occasionally, the levee or dam may break or fail, allowing water to freely flow to danger areas, causing a flood disaster.

Flood Disaster Types:

There are several types of floods that may result in a natural disaster. Floods can occur near lakes, rivers, or swampy land, creating different types of floods with different characteristics.

Riverine:
This type of flood occurs near rivers. A slow riverine flood disaster may be caused by rainfall runoff or the quick melting of snow. This type of flood disaster is usually caused by monsoons or other types of tropical storms. Fast riverine floods are usually referred to as “flash floods”, caused by convective precipitation such as thunderstorms.

Estuarine:
This type of flood disaster happens near the sea when sea tides rapidly rise due to storm winds. Tropical storms, such as cyclones cause estuarine floods.

Coastal:
A coastal flood is usually caused by severe storms at sea, such as a hurricane, but it can also be the result of a tsunami.

Catastrophic:
A wide-scale flood disaster caused by a freak event, such as a levee breakage or dam failure. Earthquakes and volcanic eruptions may also cause a catastrophic flood to occur.

Muddy:
An accumulation of water runoff, usually occurring on cropland. The sediments collected from flowing water cause muddy water to rise.

Other:
A flood may happen if water is gathered by rainfall in an area where water cannot evaporate or dissipate fast enough.

Natural Disaster Floods and Their Effects:

Natural disaster floods can cause a great deal of destruction and property damage. Cars, bridges, sewer systems, buildings, homes, and roadways may be damaged seriously by floods. They also can be quite dangerous to human and animal life. Floods can cause human and livestock casualties by drowning and later by waterborne diseases that are carried by floods.

Further effects from a flood can be contaminated water supplies. After a flood, a scarce supply of water may become a problem because water usually used for drinking becomes contaminated. Furthermore, crops and other food supplies may be completely destroyed following a flood and countries that have scarce resources may enter into a famine if food supplies are widely effected. Trees in the surrounding area of a flood may also die from suffocation.

Long-term effects of floods can be economic hardship. Natural disaster floods can cause tourism to decline, can lead to food shortages, and a lot of money may need to be allocated to rebuild structures.