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Whenever rivers are already at their full capacity of water, heavy rains will result in the rivers overflowing and flooding the surrounding land. Rivers that are covered in ice can also lead to flooding. When ice begins to melt, the surface of the ice cracks and breaks into large pieces.
Revision Note. Rivers. According to the United States Geological Survey there are over 3 million rivers around the world and 1500 river systems in the UK alone. How are rivers formed? Rivers are formed when water flows downhill due to gravity, driven by rainfall, melting snow, or underground springs.
Flooding occurs when the bankfull capacity of a river is exceeded (water spills over the banks of the river). There are a range of physical and human factors that affect flood risk.
When a river overflows its banks or the sea moves inland, many structures are unable to withstand the force of the water. Bridges, houses, trees, and cars can be picked up and carried off. Severe flooding in Bangladesh in July 2007 led to more than a million homes being damaged or destroyed.
When a river floods or overflows its channel, the area where the stream flows is suddenly much broader and shallower than it was when it was in its channel. This slows down the velocity of the stream’s flow and causes the stream to drop off much of its load.
High discharge may cause the river to overflow the banks; More of the water is in contact with land surface as the water spreads across the floodplain; Increased friction reduces velocity and material is deposited across the floodplain gradually increasing the floodplain height
10 de ago. de 2021 · Nature Reviews Earth & Environment - River floods have direct and indirect consequences for society, and can cause fatalities, displacement and economic loss. This Review examines the physical...
