A flood is an abnormal progressive rise in the water level of streams or rivers which may result in overflowing. When an area which is normally dry land becomes partially or completely submerged due to rise in water level, flooding has also occurred. Floods in the Caribbean can often be caused by heavy rainfall, dam or levee failures, tsunamis, unusually high tides, storm surges or burst water mains.
Flash floods can occur within a few minutes or hours of excessive rainfall, a dam. Flash floods often have a dangerous wall of roaring water carrying rocks, mud and other debris.
Overland flooding, the most common type of flooding event typically occurs when waterways such as rivers or streams overflow their banks as a result of rainwater and cause flooding in surrounding areas. It can also occur when the capacity of underground pipes, or the capacity of streets and drains designed to carry flood water away from urban areas are exceeded.
What are the Different Types of Floods?
Flooding is the most common natural hazard and it can occur in different ways. Take a look below to find out more about the different types of flooding.
There are four types of flooding that affect Saint Vincent and the Grenadines and the wider Caribbean:
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.
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.
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
The following are main causes of flooding in Saint Vincent and the Grenadines
- 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.
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.
A flood can come at any time and they can be very destructive. Be ready! Preparation is half the battle.
- Always monitor weather conditions
- Keep areas around your home free from garbage and debris that may block drains. Work with neighbours to achieve this in the wider community area.
- Store chemicals, important documents and electrical devices on elevated surfaces away from expected water levels.
- Purchase water proof storage bags to protect important documents.
- In case an evacuation is necessary, prepare a plan that takes disabled persons, the elderly, children and pets into account:
- Determining flood free routes to and from your home.
- Finding out where the nearest evacuation shelter is located.
- Preparing a Disaster Survival Kit (link to survival kit section)
- Store additional materials like plastic sheeting, lumber, nails, rope, wire and sandbags to assist with the effects of flooding, or to aid with reinforcement of objects that may get swept away
- Find out if your home or business is located in a flood prone area.
- Make sure your insurance plan covers flooding.
- Ensure that everyone in the household knows how to turn off the utilities.
What to do during a Flood
If a flood is likely in your area, you should:
- Remain calm and take all necessary precautions.
- Listen to the radio or television for information.
- Be aware that flash flooding can occur. If there is any possibility of a flash flood, move immediately to higher ground.
- Do not wait for instructions to move.
- Be aware of stream, drainage channels, canyons and other areas known to flood suddenly. Flash floods can occur in these areas with or without typical warnings such as rain clouds or heavy rain.
If you must prepare to evacuate, you should do the following:
- Secure your home. If you have time, bring in outdoor furniture. Move essential items to an upper floor.
- Turn off utilities at the main switches or valves if instructed to do so. Disconnect electrical appliances. Do not touch electrical equipment if you are wet or standing in water.
- Do not go sightseeing in flooded areas.
- If caught in a house by suddenly rising water move to second floor and or if necessary, to the roof. Take warm clothing and a flashlight with you - as well as battery radio. Wait for help. If you live in a single story house, seek shelter with neighbours that have larger sturdy houses.
- Use only recommended routes if you must travel.
Flooding can often cause forced evacuation. The process of evacuation is normally affected to remove a threatened community from a high risk factor.
The evacuee is often being asked to leave the security of his/her home to an impersonal setting. This is often in the form of shelters - located at some schools and churches.
Secure all personal documents and records. Since the duration of the stay away from home is unpredictable gas, electricity and water should be turned off.
If you have to leave your home, remember these evacuation tips:
- Do not walk through moving water. Six inches of moving water can make you fall. If you have to walk in water, walk where the water is not moving. Use a stick to check the firmness of the ground in front of you.
- Do not drive into flooded areas. If floodwaters rise around your car, abandon the car and move to higher ground if you can do so safely. You and the vehicle can be swept away quickly.
- Do not camp or park your vehicle along streams, rivers or creeks, particularly during threatening conditions.
Flood Driving Tips
Cars can become coffins in floods so driving should be undertaken only when absolutely necessary- for instance evacuation of persons unable to walk.
The following are important points to remember when driving in flood conditions:
- Six inches of water will reach the bottom of most passenger cars causing loss of control and possible stalling.
- A foot of water will float many vehicles
- Two feet of rushing water can carry away most vehicles including sport utility vehicles (SUV's) and pick-ups.
- Do not attempt to drive through a flooded road. The depth of water is not always obvious. The road bed may be washed out under the water, and you could be stranded or trapped.
- Do not drive around a barricade. Barricades are there for your protection. Turn around and go the other way.
- Do not try to take short cuts. They may be blocked. Stick to designated evacuation routes.
- Be especially cautious driving at night when it is harder to recognize flood dangers.
What to do after a Flood
- Listen to the radio for instructions.
- When returning home and before you enter the house, be sure that the structure is not in danger of collapsing:
- move about the building slowly
- do not touch electrical appliances or fixtures
- Open windows and doors to let air circulate. This will help remove foul odours and protect you from escaping gas. It will also help to dry out the house
- Take pictures of damage both to the house and its contents for insurance purposes.
- Get in touch with insurance company - if house was insured.
- Begin clean up as soon as possible. Throw out any perishable foods. They may be contaminated.
- You may need to hose down furniture if mud is lodged on them. Shovel out mud while it is still moist and dry rugs and carpets thoroughly.
- Make necessary repairs to stop further losses from the elements or from looting.
- Boil and store drinking water.
- Keep garbage tightly sealed.
- Cover and protect food.
- Prevent mosquito breeding by punching holes in all containers in which water can settle.
- Keep garbage tightly sealed.
- Do not walk barefooted outside, during or after a flood. Wear water boots or shoes.
- Do not go sightseeing in flooded areas.
- Do not touch loose or dangling electrical wires.
- Exercise caution when crossing bridges and passes that are near to rivers and streams. Use only recommended routes.
- Bury all dead animals as soon as possible.
- Do not go swimming in floodwaters.
Follow evacuation orders carefully.