When the ground is too saturated to absorb the water that is on the surface, flooding starts to occur because the water has nowhere to go.
Therefore it piles up on the ground causing hazardous conditions for anything that is in its path.
A flood can result from several days of heavy rain, snow-melts, hurricanes or a tsunami.
With heavy rain or lots of snow-melt, rivers can overflow their banks. However, hurricanes and tsunamis bring large amounts of water from the ocean on land.