An area usually floods for one of two reasons. Floods often occur when too much rain falls on a large area and the drains and rivers overflow. Heavy rainstorms are happening more often and last longer because of climate change. Floods can also occur in low lying coastal areas if the sea level rises because of climate change.
Floods can be devastating. They ruin homes, farms, hospitals, schools and roads and they can also spread disease.
Just 15cm of fast-moving floodwater is enough to knock you off your feet and 60cm of water can sweep a car away. Flash flooding in India resulted in scores of elephants being swept away from the Nameri game reserve.
In 2005 the US National Weather Service reported more people die each year in floods than by lightning, tornados or hurricanes.
In 2002 a severe flood in Mozambique caused lots of damage to homes and crops. Villages in Caia witnessed a skinny dog hiding from the flooding, with a tiny monkey clinging to its back – the pair, named Billy and Kiko by the villagers, have been good friends ever since.