Flood occurs when water inundated land that is usually dry, which can happen in a multitude of ways. A flow, spreading over the surrounding property, called a floodplain, may be flooded by heavy rain, a ruptured dam or levee, rapid melting of snow or ice, or even an unfortunately located beaver dam. Human factors raise flood risk like urbanisation, since there are more impermeable surfaces in cities and towns. Deforestation since the destruction of trees decreases the quantity of intercepted water and increases run-off.
Due to enhanced denitrification during anaerobic soil conditions that continue during flooding, flooding often causes soil nitrogen loss. For crop development, nitrogen is essential, and most farmers apply some additional nitrogen to their crops. Effects of flood can drastically alter the amount of nutrients in the soil available to plants. Soil lost due to erosion will take with it important nutrients and organic matter that are available to plants. Flood sediment deposition can increase soil levels of phosphorus, nitrogen, silicon, and potassium.
What are the Causes of Floods?
Floods are caused for many reasons, strong and prolonged precipitation, heavy moulting of snow, changes in the flow of a river, silting of river beds, collapse of dams, landslides, erosion, unscientific land use and tsunamis.
An overflow of water on usually dry land is a flood. Most often, this is due to an overflowing river, a dam failure, snowmelt, or heavy precipitation. Tsunamis are less common, and storm surges are less common. People attempt to transfer themselves and their most valuable possessions to safer ground quickly during a storm.
In the catchment areas of rivers and in badly drained areas, heavy rainfall is the main causes of flood. If the water level increases above the banks or dams of the river, the water begins to flood. Floods can look very different because anywhere from a few inches of water to several feet is submerged by flooding.
Health Impacts of Floods
Injuries, diseases, poisoning and greater problems with mental wellbeing are health consequences observed during and after floods. Infectious disease outbreaks are uncommon. Millions of people will be affected by sea level rises and storm surges, which cause coastal flooding. Naturally, flooding occurs along every river and coastal region. Flood waters can carry nutrient-rich sediments that contribute to vegetation in a fertile setting. By providing a range of habitats for fish and other species, the floodplains are beneficial for wildlife.
Contamination of the supply of drinking water is the principal cause of waterborne diseases during flooding. Floods introduce bacteria, parasites and viruses into the drinking water system, resulting in waterborne disease outbreaks. Atmospheric conditions that lead to heavy rain or the rapid melting of snow and ice cause extreme flooding. Geography may also make it more likely that a region would flood.
Instead, disasters show the vulnerability or susceptibility of people when faced with floods, cyclones, volcanic eruptions, landslides, or other potentially harmful natural phenomena. Small barriers in ditches and fields, or notches cut into embankments, both of which channel the water into open land, are natural flood defence features.