What are the Different Types of Floods?
There are four types of flooding that affect Jamaica and the wider Caribbean:
- Flash Floods:
Flash floods are the result of heavy rainfall or cloudburst over a relatively small drainage area. Flash floods carry highly destructive flood waves and are most common in mountainous areas or in steep places that have streams flowing though narrow canyons.
- Riverine Floods:
These occur when a large amount of rain falls in river systems with tributaries that drain large areas containing many independent river basins. They may last a few hours or many days depending on the intensity, amount and the distribution of the rainfall.
- Tidal Flood:
This results when large bodies of water, like the sea or lakes, overflow onto bordering lands. They are mainly caused by high tides, the heavy rains that accompany hurricanes, waves created by high wind surges created by storms, and long waves produced by earthquakes out at sea.
This is a slow build up of water in depressions, sinks, areas with clay base soil, and slow percolation rate, for example, flooding in New Market.
What Causes Floods?
The following are main causes of flooding in Jamaica:
- Heavy rainfall resulting from tropical weather disturbances
- Improper agricultural practices
- Inadequate design of drainage channels and structures
- Inadequate maintenance of drainage facilities, blockage by debris brought by flood waters
- Construction of settlements in flood plains
Flooding is also a natural feature of drainage systems and of rivers and streams. It occurs when drainage channels are filled and the rivers and streams can no longer accommodate the excessive water generated by severe weather conditions. The drainage channels then overtop their natural or artificial banks and water enters the surrounding lands to cause flooding.
Also human activities, which damage the environment, for example, sand mining, deforestation and poor garbage disposal, increase the risk of flooding.
Areas most likely to be worst affected by flooding are:
- Low-lying coastal areas
- Areas near gully banks
- Flood plains of major rivers
- Lower sections of closed limestone valleys (e.g. Newmarket)
- Areas vulnerable to landslides
- Low-lying coastal towns and villages
Persons who live close to these areas are urged to be on the alert in case of a disaster as they are most vulnerable to flooding.
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What are the Effects of Floods?
- Disrupt one's personal, economic and social activities.
- Set back the nation's security and development by damaging or destroying roads, buildings and other infrastructure.
- Cause death by drowning.
- Lead to insufficient food supply, which can lead to famine.
- Destroy crops and livestock.