CARIBBEAN STUDIES

Droughts and floods

WHAT IS A FLOOD?

• It is a natural event or occurrence where a piece of land (or area) that is usually dry land, suddenly gets submerged under water. Some floods can occur suddenly and recede quickly. Others take days or even months to build and discharge.

TYPES OF FLOODS

Flash floods – usually last a very short time. May occur within hours or even within minutes.• These floods occur suddenly from heavy rainfall or dam breaking. • They are the most destructive and can be fatal. There is usually no warning, no

preparation and the impact can be very swift and devastating.Rapid on-set floods- this type takes slightly longer to develop and the flood can last for a day or two only. • It is also very destructive, but does not usually surprise people like Flash floods. • With rapid on-set floods, people can quickly put a few things right and escape

before it gets very bad.

Types of floods

Slow on-set floods - as a result of water bodies over flooding their banks. • They tend to develop slowly and can last for days and weeks. • They usually spread over many kilometers and occur more in flood plains

(fields prone to floods in a low-lying areas). • The effect of this kind of floods on people is more likely to be due to

disease or malnutrition

Methods of flood control

• Humans cannot stop the rains from falling or stop flowing surface water from bursting its banks. These are natural events, but we can do something to prevent them from having great impact.

• Educating the people:In many developing countries, drainage systems are chocked with litter and people have little knowledge of the effects that can have during a rain. When it rains, waterways and culverts are blocked by massive chunks of litter and debris, and water finds its way into the streets and into people’s homes. Education is therefore very important, to inform and caution people on the dangers of floods, what causes floods, and what can be done to minimise its impact• Vegetation:Trees, shrubs and grass help protect the land from erosion by moving water. People in low-lying areas must be encouraged to use a lot of vegetation to help break the power of moving flood water and also help reduce erosion.

Methods of flood control

• Retaining wallsIn some places, retaining walls levees, lakes, dams, reservoirs or retention ponds have been constructed to hold extra water during times of flooding.

• Detention basinThese are small reservoirs built and connected to waterways. They provide a temporary storage for floodwaters. This means in an event of flooding, water is drained into the basin first, giving people more time to evacuate. It can also reduce the magnitude of downstream flooding.

Methods of flood control

Other method used to prevent floodingControl the water level dams pumping stations

Build barriers

Alter the river’s channel

Control land use

Causes of flooding

Torrential rain or raining extremely hard

Causes of flooding• Dam collapse

Causes of flooding• Snow melt

Causes of flooding

• Tsunami caused by underwater earthquake

Causes of flooding….

Monsoon rain

Global warming

Deforestation

Effects of flooding

Floods can have devastating consequences and can have effects on the economy, environment and people.• EconomicDuring floods (especially flash floods), roads, bridges, farms, houses and automobiles are destroyed. People become homeless. Additionally, the government deploys firemen, police and other emergency apparatuses to help the affected. All these come at a heavy cost to people and the government. It usually takes years for affected communities to be re-built and business to come back to normalcy. Did you know that the cost of all floodings in the USA in 2011 was $8,640,031,956 (approx 8.5B USD) — http://www.nws.noaa.gov/hic/

Effects of flooding

• EnvironmentThe environment also suffers when floods happen. Chemicals and other hazardous substances end up in the water and eventually contaminate the water bodies that floods end up in. In 2011, a huge tsunami hit Japan, and sea water flooded a part of the coastline. The flooding caused massive leakage in nuclear plants and has since caused high radiation in that area. Authorities in Japan fear that Fukushima radiation levels are 18 times higher than even thought.Additionally, flooding causes kills animals, and others insects are introduced to affected areas, distorting the natural balance of the ecosystem.

Effects of flooding

• People and animalsMany people and animals have died in flash floods. Many more are injured and others made homeless. Water supply and electricity are disrupted and people struggle and suffer as a result. In addition to this, flooding brings a lot of diseases and infections including military fever, pneumonic plague, dermatopathia and dysentery.Sometimes insects and snakes make their ways to the area and cause a lot of havoc.

DroughtsImpact of

Geographical Phenomena

What is a Drought?

• Drought is different from tornadoes, hurricanes, and floods. It can be more difficult to detect and it can last much longer than other weather events. We don’t have “watches” or “warnings” for drought like we do for other natural hazards. But just because drought is different from the other natural disasters doesn’t mean we can’t plan for it and take steps to help protect ourselves from the effects of drought. In fact, the National Drought Mitigation Center helps people plan for drought. • The term mitigation relates to drought. Mitigation means taking actions

before, or at the beginning of, drought to help reduce the impacts (or effects) of drought. We can do many things to mitigate drought.

What is a Drought?

• Drought is a protracted period of deficient precipitation • Droughts are predominantly associated with agriculture and so they result

in extensive damage to crops, resulting in loss of yield.

What Causes Droughts?

• A traditional drought is caused by an extended period of below average rainfall in an area.• This low rainfall however can be triggered by numerous factors such as poorly planned agricultural endeavorsHigh temperaturesHigh water consumption rates andoverpopulation

What Should You Do In A Drought?

• The most common thing to do in a drought is to conserve water.• Water conservation however can take place through a myriad of ways.

These include:Using water saving devicesXeriscaping andWater recyclying

Xeriscaping

• Xeriscaping is a type of landscaping that uses little water by only using plants that are native to the area you live in. • Native plants usually need less water to grow or can make better use of the

water that is available to them than other types of grasses, trees, and shrubs.• The keys to xeriscaping are to use only as much water as the plants need

and to choose landscaping designs and plants that make use of the available rainfall. 

Social Impacts of Droughts

• Hunger• Malnutrition• Mortality• Low food production• Migration• Anxiety• Stress• Depression

Economic Impacts of Droughts

• Farmers lose money• Businesses lose money• Government has to spend more• Several livelihoods are affected

Drought Prevention

• Education• Stop Pollution• Water Conservation • Water Storage