THE IMPACT OF STORMS AND FLOODING IN AFRICA
Flooding occurs when a body of water (such as a river or lake) overflows onto dry land. This is normally caused by periods of high rainfall. Floods can cause a lot of damage to land and buildings. They can also be very dangerous for people.
WHAT CAUSES FLOODING?
Floods usually occur during the rainy season. For most of Sub-Saharan Africa this occurs between June and September. This is the period when countries get most of their yearly rainfall.
Often heavy rainfall is caused by storms. These forms of extreme weather cause high winds and rainfall over local areas.
HOW ARE STORMS FORMED?
When temperatures are warm, air rises. As air rises it cools down. This allows water in the air to change from gases into liquid (a process known as ‘condensation’). This process releases a lot of heat. When condensation occurs, clouds form out of lots of liquid water droplets. When enough heat is released water droplets in clouds will fall to the ground as rain.
This process needs both water on the ground and warm temperatures to happen. This means that some warm areas like deserts won’t get much rain as they don’t have a lot of water.
WHAT ARE THE EFFECTS OF FLOODS?
Floods can have many economic effects. Floodwater can destroy houses, roads, farmland and cars. This means that many people may be cut off from help by the water. Crops and livestock can drown if flooded. This can damage many farmers yearly income. Farmland may also take a long time to recover.
If there is a lot of rainfall over a short amount of time then ‘flash flooding’ can occur. This is when flooding happens very quickly and covers a wide area. This can be very dangerous as floodwater can very quickly surround buildings and trap people inside.
If heavy rains fall over hilly areas then mudslides can occur. When rainwater mixes with soil it can flow downhill and cover areas with mud. Mudslides can happen very quickly and can flow at high speeds. This means that they can destroy and cover buildings and roads. In August 2017 a mudslide hit Freetown (the capital city of Sierra Leone). This buried thousands of houses and damaged many businesses.
If floodwater remains for a long time then diseases may be spread. These often include Dysentery, Typhoid and Cholera. In towns and cities, sewage can mix with flood waters. This can pollute sources of drinking water. Insects like mosquitoes can breed in floodwater. This also increases the risk of diseases like Malaria.
Avoiding drinking floodwater may help to prevent some of these diseases from spreading. Finding an area of high ground would also reduce the risks of being caught in flash flooding.
THE UPSIDES OF FLOODING
Although most effects of flooding are bad, many people across the world rely on floods. When land near a river floods, the water can leave lots of nutrients (used to help plants grow). These make the land more healthy and fertile. This means that farmers can produce higher crop yields each year. Farmers living by the Nile River in Egypt depend on flooding to help keep their farmland healthy.