Floods
Floods are when large quantities of water overflow an area of land that is usually dry.
Rain is the most common cause of flooding. Large amounts of percipitation can cause a flood. Depending on the rainfall distribution, the amount of rain, and soil moisture content, short rainfall period can also result in flooding.
Theyeare four types of flooding:
- Fluvial floods (river floods)
A fluvial, or river flood, occurs when the water level in a river, lake or stream rises and overflows onto the neighboring land. The water level rise of the river could be due to excessive rain or snowmelt.
- Pluvial or flash floods
A pluvial flood occurs when an extreme rainfall event creates a flood without there being a large body of water, like a lake or river, that overflows. There are two common types of pluvial flooding; Surface water floods occur when an urban drainage system is overwhelmed and water flows out into streets and nearby structures. It occurs gradually, which provides people time to move to safe locations, and the level of water is usually shallow (rarely more than 1 meter deep). Flash floods are characterized by an intense, high velocity fast moving water triggered by rain falling within a short amount of time within the area.
- Coastal floods (storm surge)
Common causes of coastal flooding are intense windstorm events occurring at the same time as high tide (storm surge), and tsunamis. Common causes of coastal flooding are intense windstorm events occurring at the same time as high tide (storm surge), and tsunamis.
- Urban flooding
Caused by flash floods, excessive rain, urban floods are any form of flood occurring in densely populated areas. Areas with poor drainage and sewage systems are more prone to this sort of flooding.
The frequency of flooding depends the location and the probability of a certain amount of rainfall or or waterlevel each year. One could look at the different flood zones, to predict how big the floods are going to be. Because of climate change we can expect more frequent and severe floods.
Some floods can occur suddenly and recide quicly whereas others others take several days or even weeks to form and recide all depending on the variation of size, duration and the area affected.
Did you know: civilizations throughout history developed ingenious flood control measures. The ancient Egyptians constructed the Aswan Dam to regulate the Nile River's flow, showcasing early human efforts to harness and manage water.
When a flood occurs there is a chance of there being damage done to property and environment and potentioal loss of life. Reparing and replacing flood damaged roads, bridges, utileties and public infrastructure cost a lot of money. Flooding can also bring contamination and diseases. Raw sewage leaked chemical waste and hazardous material can often be found in floodwater. It can pollute drinking supplies and cause infections.
However some floods, like the annual flooding of the river nile is neccecary of the ecosystems and comuneties to survie. In the case of the nile, the floood replenishes the earth with neutrients making it an optimal choice for crops.