Flood Danger: Types of Floods

5/31/2022 (Permalink)

Floods continue to affect many people worldwide due to increasing populations and the destruction of wetlands and other natural barriers.

Flooding occurs when rainwater cannot drain quickly enough, causing floods to form on land and at sea. Floods continue to affect many people worldwide due to increasing populations and the destruction of wetlands and other natural barriers. Heavy rains are often the cause of flooding, but they may also be caused by other factors, such as melting snow.

5 Main Types Of Floods

1. Flashfloods

Most commonly known as 'whiplash' floods, sudden downpours of heavy rain cause flash floods. They usually occur in low-lying areas like river valleys and floodplains. Flash floods can be unpredictable - one moment, the ground is dry, and you can walk across; the next, a torrent of water rushes through, causing severe damage and drowning people who have been sight-seeing on foot. Flash floods can also be caused by heavy rainfall around or after rainfall has stopped.

2. Landslides

Landslides usually occur when the ground becomes saturated following heavy rainfall. When the rain ceases, the ground is left unsupported and begins to slide downhill. Landslides may occur on slope sides or in valleys but can also be triggered by ground-level heavy rainfall. Landslides are usually associated with rock, clay, and soil types that become slippery when wet.

3. Seepage

It is caused when surface water containing dissolved materials seeps into underground aquifers through cracks or fault lines. The water can then form into a saturated aquifer and start seeping up through the ground, through cracks and fissures in rock or faults. The ground can become unstable and cause landslides, floods, and earthquakes.

4. Tsunami

Tsunamis occur when a large volume of water piled in the sea causes a giant wave to break out over a wide area, generally around coastal areas. Tsunamis can travel at 600 km 373 miles an hour, destroying everything in their paths, including people, houses, and ships.

5. Storm surge

When a storm front passes over the sea from the ocean, it creates a wave that moves parallel to the coastline. If this is combined with high winds and waves already present in the seawater, the result can be storm tides known as storm surges. When they reach the coast, they cause widespread flooding on land around a country's coastline. In the UK, for example, storm surges can be caused by the extratropical cyclone created when warm air meets cold air over the sea.

A flood hazard map can show areas of risk and associated threat levels. The level of flooding varies from one flood to another in line with such factors as duration, intensity, frequency, and catchment area. Flooding in rivers occurs due to rainfall not being absorbed or held back by natural barriers such as wetlands and dams. When rainfall exceeds the capacity of natural barriers, water backs up. It can flood valley floors called flash floods or overflow into surrounding areas, often referred to as riverine flooding. A combination of flooding causes problems during extreme weather events. Landslides occur when saturated soil is loosened by rain or melting snow, and debris flows can follow heavy rainfall. Flood water then rushes down steep slopes in torrents causing rivers to burst their banks and inundate surrounding land.