Floods occur when water covers or soaks land that is normally dry. They can be slow-developing or sudden and happen in a variety of different ways depending on rain intensity, topography and soil conditions.
There are few places on Earth that don’t experience flooding. It can be dangerous and devastate an environment, especially if it is not able to recover between floods.
Climate change has a significant impact on how often and how intensely floods happen. Warmer-than-average ocean temperatures cause more evaporation, which leads to more moisture in the air. This makes it more likely that rain will fall in high volumes and lead to large, widespread flooding.
In wetland habitats, floods play a crucial role in supporting fish and wildlife and creating islands, channels and other habitats that support wildlife, people and plants. Floodwaters also provide fresh, clean water that helps ecosystems and crop lands. They filter out pollutants and help rebalance the nutrients in rivers. Floods can also wash out invasive species and flush them from the system, helping native plants and animals thrive.
When it comes to human safety and well-being, people are most affected by the direct impact of floods and the associated loss of housing, jobs and utilities like electricity, gas and water supply. If floodwaters are contaminated with sewage or other chemicals, they can also spread disease. People who come into contact with polluted flood waters are at risk of getting illnesses like typhoid, malaria, hepatitis A and cholera.