Heavy, consistent and prolonged rainfall coupled with the overflowing of rivers and other water channels is one of the main causes of flooding. As rainwater reaches and fills the river channels, the water spreads on the floodplain or the land next to the river and causes flooding.
Flooding after heavy rainfall is also affected by certain factors, including steep and shallow river channels, lack of vegetation and concrete drainage basins that prevent the water from percolating back to the ground and causing water to run faster on the floodplain. Insufficient drainage systems, poor maintenance of waterways and faulty sewers also contribute to flooding.
The cause of flooding also varies by geographical location. High tide combined with a stormy weather and low atmospheric pressure is one of the main causes of flooding in coastal regions. Hurricanes bring destructive storm surges, which can quickly uplift shore water by up to several meters. A storm surge can penetrate the beach and low-lying areas farther inland.
A tsunami or tidal wave produced by an earthquake or a disturbance on the ocean floor can generate a set of waves that slowly builds up and increases in velocity in shallower water. Unlike a storm surge, a tsunami comes in a form of an immense wave that, if amplified tremendously, can cause flooding and excessive damage to properties.