Floods occur on our planet as a result of various factors such as natural weather phenomena, human constructions, human activities or even climate change.
In this Green Ecology article, we analyze the causes and consequences of floods, to better understand this problem that can be more or less dangerous according to various factors. In addition, we will see that there are situations that are controllable and even predictable and can be avoided, while other times it is totally unexpected and uncontrollable.
What are floods?
We defined a flood as a massive occupation by water of areas that were dry. The factors that lead to a flood can be a temporary rise in the level of a river, lake or sea. Although sometimes unavoidable, sometimes floods can be situations that can be controlled by human activity, due to the misuse of land near watercourses.
It is estimated that floods are the natural disaster or catastrophe that causes the most deaths on the planet. During the 20th century, it has been estimated that around 3.2 million people have lost their lives due to this cause, which constitutes more than half of the victims of natural disasters during the same period.
Types of floods
In addition, there are several types of floods, which can be classified as follows:
- Storm Floods: this type of floods are produced as a consequence of heavy rainfall concentrated in a particular area. The high concentration of rainfall causes the land to become saturated and the excess water begins to accumulate, which can last hours or days, until it begins to evaporate and the land recovers.
- River flooding: This type of flooding occurs when river water overflows and reaches the land near the riverbed.
- Coastal floods: These occur as a result of intense winds, such as a stormy cyclone. This flood enters towards the coastal areas and covers large areas of land.
For example, the image above is a coastal flood, where you can sense that a promenade has been totally flooded.
Causes of flooding
The main causes of floods are multiple, but generally we can classify them as natural or as a result of human activity:
Natural causes of floods
Intense rainfall: can be caused by rain, tropical storms or hurricanes. These floods can be produced as a result of rising river levels. The more water that falls and the longer the rainy season, the higher the probability of water overflows. To contain these problems, dams or dikes are often built to store large amounts of water from different sources. This water can then be released to supply plantations, irrigated land or to generate energy.
Accumulation of sediments: these accumulations form large containment barriers for water, which as the amount (and pressure) of water increases ends up overflowing, allowing large amounts of water to flow mixed with mud, logs or stones.
Snow melt in high mountains: the snows accumulated during the winter normally melt during the spring, but if there are strong waves of heat, this process accelerates, to the point of being able to increase the levels of the sea or rivers and make them invade the land.
Tsunamis: they take place as a consequence of earthquakes in the sea. This causes marine plates to move, generating large waves of water that can exceed the water levels on the coast and invade the land.
Human causes of flooding
Deforestation: Due to human activities, forests and jungles are massively cut down, which is a big problem, because the vegetation retains large amounts of water, which it releases even after the rains have stopped.
Water pipes in cities that overflow due to rainfall.
Different constructions in cities made in areas too close to the sea or rivers or constructions made in areas previously occupied by the sea or rivers. As a consequence, when different natural phenomena occur, water can flood the land.
Ruptures of dams or dikes, which release large quantities of retained water.
Dumping of waste or materials that block the riverbeds.
Climate change, which can accelerate other processes such as snow melting.
Many of these phenomena can be classified as natural and human at the same time. In addition, the causes of floods are often a combination of human and natural phenomena, such as tsunamis and buildings too close to the sea.