We explain what floods are and the causes and consequences they present. Also, what are their characteristics, types and examples.
What are floods?
It is known as overflow floods or the accidental accumulation of water in a region of territory that is normally dry, usually as a consequence of meteorological phenomena and / or imbalances in the water level of the regions. They are mostly categorized as natural disasters and can have an extremely high human and material cost.
Floods, in principle, can be local (when they affect a certain community or locality) or extensive (when they cover entire regions, cities or entire river basins). In fact, the damage caused by one can be felt for years and can sometimes change the geological nature and relief of a region forever .
Causes of floods
Floods can cause rivers and lakes to overflow.
The causes of floods can be:
- Excess rain: Especially when it comes to uninterrupted rains over the course of days that quickly exceed the absorption capacity of the soils .
- Overflowing rivers and lakes: As a consequence of the growth of its margins due to the intense rain in the area or at the headwaters of the river , as well as the melting of mountain ice caps.
- Dam or levee ruptures: That although they are human accidents, they usually generate a violent and very damaging flood when they exceed the natural channel through which the water was supposed to pass.
- Hurricanes or tsunamis: And other extreme weather events such as storms or even earthquakes (sometimes causing tsunamis or waterspouts), can dump gigantic amounts of water onto land, either as rain or as a large wave that surpasses the coastal limits and enters the mainland. .
Consequences of floods
The consequences of floods vary according to their intensity and duration, but generally they have to do with:
- Destruction of crops and crops: Which can then have an economic or humanitarian impact, as there will be less food.
- Destruction of transportation routes: And interruption of all economic and logistical activity in a city or region.
- Destruction of entire homes and villages: Sometimes in a very few moments, especially when floods are accompanied by landslides, avalanches or other dangerous phenomena.
- Death and injuries of varying severity: Since the forces of water can drag vehicles, people , knock down houses and drown those who cannot swim or are in disadvantaged situations.
- Increase in diseases: Not only because of the injuries caused during the flood and those resulting from urban destruction, but also because of the accumulation of water in many places, which allows the proliferation of mosquitoes and many epidemics.
- Modifications of the relief: For a sudden and violent flood can forever change the topography of the place where it occurred.
Types of floods
Slow-onset floods give time to seek solutions.
The types of floods depend on the speed with which the disaster occurs:
- Slow onset. Those that can take weeks or months to raise your water levels and usually give you time to come up with a solution.
- Quick to appear. They occur in a much shorter period of time and therefore are much more destructive since they do not give room for preparation or warning.
- Sudden. The worst of all occur in a few moments and are usually the consequence of other more serious catastrophes.
Differences with flooding
Waterlogging is basically a type of flood that is due to the supersaturation of the soils and the accumulation of water on the ground that, in general, never reaches too high a height but does destroy crops, clog pipes, etc.
For this, the permeability of the soil is key , since depending on the type of soil there will or will not be a risk of faster or slower waterlogging. They are common in rural regions, such as savannas or marshes.
There are many organizations in the world that are dedicated to fighting floods.
There are numerous early warning systems to anticipate the arrival of floods, especially when faced with processes of climate change or seasonal periods of storms.
In general, these systems are based on mathematical formulations and calculations that allow specialists to predict the flood margin of rivers and lakes and can, in the best cases, gain days in advance that can translate into lives saved.
At the international level, many organizations are dedicated to combating the effects of floods.
Most vulnerable regions
Usually the coastal plains and low relief regions are always more susceptible to flooding. Much of India , laced with rivers, or of the State of Florida, Louisiana and New York in the United States, for example, are flood regions, as is Canton in China and Ho Chi Minh City in Vietnam.
Other regions that chronically suffer from the flood are the north of Argentina , part of Uruguay and the islands of the Caribbean , Asia Minor and the Mediterranean area, which suffers from the so-called “cold drop” during the month of October.
Flash flood or lightning flood
Flash floods are associated with heavy rains in mountainous regions.
This term borrowed from English is used to refer to floods in record time , that is, those that occur due to the sudden and unpredictable rise of some river flow and, above all, some mountain flow or boulevard.
The US National Weather Service links them to heavy rains in mountainous regions or headwaters and are particularly dangerous in dry or sparsely vegetated areas.
Prehistoric or mythical floods
Many floods in ancient times were recorded historically or mythologically in the texts and traditions of humanity, in which there is usually always a reference to a “Great Flood” that, according to what is interpreted, would come to cleanse the earth of its sins and save only to the righteous.
The end of the last ice age , in that sense, must have been full of floods as the glaciers melted, which together with various tectonic faults gave rise to lakes, rivers and other water reservoirs.
How to prevent floods?
Preventing global warming helps reduce flooding.
Since ancient times are erected defenses against water as breakwaters, barriers, walls or intricate drainage systems and irrigation to protect cities from flooding from the sea or rivers.
Not much more can be done about it other than keeping the population trained for the dangerous situations that a flood can bring.
On the other hand, the phenomenon of global warming promises to submerge us under the sea , since the melting of the poles raises the level of sea water, as in fact it has already been happening.
Preventing warming through ecological measures, then, also implies preventing floods.
Examples of floods
Some of the most famous floods in history were:
- The great flood of the Mississippi River of 1927. In the United States, which moved about 65,000 cubic meters of water per second and flooded more than 70,000 kilometers that summer, killed 246 people and left a balance of 400 million dollars in destruction.
- The overflow of the Amazon in 1953. When a flow of 370,000 cubic meters of water per second overflowed this huge river that contains 20% of the planet’s fresh water.
- The Alaska Volcanic Flood. Called Aniakchak Flood by the locals, it occurred 10,000 years ago due to the eruption of a volcano whose crater, over time, filled with water, eroded the caldera and 1 million cubic meters of water per second overflowed towards the surroundings.
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