Floods

Imagine weeks and weeks of endless rain. The water in rivers and lakes rises higher and higher until they overflow. The water starts to run over the ground, covering larger and larger areas of land. Everything is washed away, and the land becomes flooded. Stories about floods have been told by different cultures and religions across the world for thousands of years.

Many of the ancient civilisations around the world believed that floods were sent by gods or deities to punish humans for their disobedience or misbehaviour. Then, it might have seemed the only explanation for such a powerful force of nature! Today, however, we know much more about the different causes of flooding. Most floods happen when rain falls faster than the soil can absorb it or rivers can carry it away. Snowy areas can have floods too.

When the snow melts in spring, it can make a lot of water quickly, causing rivers to overflow. Sometimes, big chunks of ice can block rivers, stopping the flow of water and acting a bit like a dam. When this ice jam breaks, the water it holds might rush down the river all at once, causing flooding. Man-made dams can cause this to occur as well. If a dam breaks or collapses, the wall of water it holds back will rush rapidly downstream, likely flooding the surrounding area.

Some areas are more likely to flood than others. Low-lying areas near rivers, known as floodplains, may flood every year. Water that doesn't get absorbed into the ground and instead flows over it is called runoff. Runoff happens on lots of different surfaces, but especially on ones that can’t absorb water at all, like roads, sidewalks, parking lots, and buildings. This means that some cities are especially at risk of flooding.

The ocean can flood too! Unusually high tides or storms like hurricanes can cause areas along the coast to flood. Floods can affect both the environment and human communities. The faster floodwater moves, the more damage it can do to anyone, or anything, in its path. Floodwaters can be strong enough to uproot trees, move boulders, and wash away soil and plants, leading to habitat loss for plants and animals.

Floodwaters can also be dirty. As they move, they can pick up dirt, chemicals, fertilisers, pesticides, and litter from the ground. This can harm animals and make water unsafe for humans. Floods can damage buildings, roads, and bridges. Sometimes, we have to leave our homes to stay safe.

This is called an evacuation. Usually, floods take a few hours or days to happen, so we can prepare and evacuate in time. But when storms drop large amounts of rain in a short time, floods can happen very quickly, sometimes in only a few minutes. These flash floods are the most dangerous types of floods because they occur with little or no warning. Floods are one of the most destructive types of natural disaster, affecting millions of people around the world every year.

A flood can last for minutes or weeks. It may be just a few centimetres of water, or it may cover a house to the rooftop! By understanding what causes floods, knowing where they might happen, and what they can do, we can take steps to stay safe!