Floods: Definition, Types, Causes and Effects

Floods occur when there is an overflow of water onto normally dry land. This can happen due to heavy rainfall, melting snow or ice, storms, or other factors that cause water levels to rise beyond their usual limits. Floods can lead to widespread damage, affecting homes, infrastructure, and the environment.

In this article, We have discussed the Definition of Floods, Types of floods, it’s causes – their impact, and many more.

Let’s dive right in.

Floods: Definition, Types, Causes and Effects

Floods Definition

Floods are natural disasters characterized by the overflow of water onto normally dry land, submerging it and causing various degrees of damage. This overflow can result from heavy rainfall, rapid snowmelt, storm surges, dam failures, or other events that lead to an increase in water levels. Floods can occur in rivers, coastal areas, urban regions, and other landscapes, and their impact can range from localized to widespread, affecting communities, infrastructure, agriculture, and the environment.

Though the main reason for floods is monsoons, the situation of river basins, changing of river courses, and narrowing of river channels due to human settlements, excessive cutting of trees in the hill slopes, unmanaged development work being carried out in hilly areas, etc are other factors responsible for floods.

According to the water resource development of the Government of India, 60% of the losses caused by the floods are due to river floods and 40% by excessive and cyclonic rainfall. The National Flood Commission has estimated that about 40 million hectares of land area of the country is flood-affected. Despite various flood control methods about 7.7 million hectares of land, which includes 3.5 million hectares of gross cultivated land is affected by floods every year. When floods are at their peak about 10 million hectares of land gets affected.

Floods Overview

The following is the complete overview of Floods:

Aspect	Description
Definition	An overflow of water that submerges usually dry land; may result from various factors such as heavy rainfall, snowmelt, storm surges, or infrastructure failures.
Types	– Areal: Water accumulates in flat areas due to rapid rainfall or snowmelt.
	– River: Flooding in river and stream channels, caused by factors like sustained rainfall, snowmelt, monsoons, or cyclones.
	– Coastal: Storm surges, high tides, and large wave events lead to flooding in coastal areas.
	– Urban: Inundation in built environments due to overwhelmed drainage systems, often exacerbated by impervious surfaces.
Causes	Prolonged heavy rainfall, snowmelt, severe winds, high tides, tsunamis, dam failures, and human activities like deforestation and urbanization.
Climate Change	Increasing frequency and severity of floods due to climate change, including sea level rise, extreme weather events, and changes in precipitation patterns.
Positive Impacts	– Recharges groundwater.
	– Makes soil more fertile.
	– Increases nutrients in soils.
	– Provides water resources in arid regions.
Negative Impacts	– Loss of life and property damage.
	– Economic hardship and damage to infrastructure.
	– Health impacts including drowning, injuries, waterborne diseases, and mental health issues.
	– Disruption of power supply, sewage disposal, and transportation infrastructure.
Flood Control Measures	– Detention basins, levees, bunds, reservoirs, weirs.
	– Emergency measures like sandbags and inflatable tubes.
	– Coastal defenses such as sea walls and beach nourishment.
	– Erosion control measures in riparian zones.
	– Flood controls like dams to reduce flood occurrence and severity.
Flood Risk Management	– Repair and expansion of sewer systems and stormwater infrastructure.
	– Green infrastructure (SUDS) to reduce impervious surfaces and promote natural drainage.
	– Conversion of flood-prone areas into parks and playgrounds.
	– Adoption of ordinances for on-site stormwater retention, elevated buildings, and flood-resistant designs.
	– Consideration of beavers and other species for natural flood control.

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Causes of Flood

The following are the Natural and Man made causes of Flood:

Natural	Man made
Heavy rain: It is characterized by high amounts of precipitation falling quickly, usually in a restricted area, and having brief warning periods because of its convective origin.	Deforestation: It is the term used to describe the disappearance or thinning of forests due to tree cutting. Humans use the space that has been cleared by deforestation to build highways, factories, homes, dams, and agricultural land.
Cyclone: It is a massive air mass that revolves around a powerful low-pressure center. . The centre of a cyclone is a calm area. It is called the eye of the storm. It is a region free of clouds and has light winds.	Lack of drainage system: Poor drainage caused by the shape of the landscape or inadequate drainage systems can damage buildings and move soil from where it’s needed to where it causes trouble. The effects of poor drainage systems extend beyond single properties and can have an impact on roads, waterways, and health.
Change in river: Firstly, sediment size decreases due to erosion, which causes sediment to get finer and smoother. This happens due to hydraulic action, abrasion, attrition and solution which act on the sediment throughout the course of the river. Another characteristic of the river that changes is the channel width and depth.	Population Pressure: Population pressure, a term summarizing the stress brought about by an excessive population density and its consequences, is used both in conjunction with human overpopulation and with other animal populations that suffer from too many individuals per area (or volume in the case of aquatic organisms).
Tsunami: It series of extremely long waves, It are very long wavelengths of water caused by a large and sudden displacement of the ocean due to earthquakes, volcanic eruptions etc. These are also called seismic sea waves and are one of the most powerful and destructive natural forces.
Glacial Lake Outburst: It is also known as a Glacial Lake Outburst Flood, or GLOF, is sudden release of water from a lake fed by glacier melt that has formed at the side, in front, within, beneath, or on the surface of a glacier.

Effects of Flood

Here are some key and important effects of floods:

1. Loss of Life:
   • Floods can result in tragic loss of human lives through drowning and injuries.
2. Property Damage:
   • Floodwaters cause extensive damage to homes, buildings, and infrastructure, leading to significant financial losses.
3. Displacement of People:
   • Flooding forces people to evacuate, causing temporary or long-term displacement.
4. Economic Impact:
   • Floods have a substantial economic impact, damaging businesses, agriculture, and infrastructure.
5. Agricultural Losses:
   • Floods can submerge farmlands, leading to crop losses and affecting food production.
6. Infrastructure Damage:
   • Critical infrastructure, including roads and bridges, may be damaged or destroyed, disrupting transportation.
7. Water Contamination:
   • Floodwaters carry pollutants, posing health risks through contaminated drinking water sources.
8. Spread of Waterborne Diseases:
   • Stagnant water after floods promotes the spread of waterborne diseases like cholera and typhoid.
9. Environmental Impact:
   • Floods harm ecosystems, causing habitat destruction, loss of biodiversity, and soil erosion.
10. Infrastructure Failure:
    • Failures of flood control structures can worsen flooding and increase damage downstream.

Precautions and Prevention of Floods

Here are some important precautions and prevention measures of floods:

Precautions Measures:

1. Safe Drinking Water:
   • Ensure a continuous supply of safe drinking water to mitigate the risk of waterborne diseases.
2. Avoid Contact with Floodwater:
   • Refrain from using floodwater for activities like cleaning, brushing teeth, or preparing meals due to contamination risks.
3. Electrical Hazards:
   • Be cautious of electrical dangers, as submerged electrical lines can pose a serious threat. Avoid contact with floodwaters to prevent accidents.
4. Food Safety:
   • Discard any food items that have come into contact with floodwater to reduce the risk of waterborne diseases.
5. Hygiene Practices:
   • Wash hands thoroughly with soap and water, especially after touching floodwater, to maintain proper hygiene.
6. Dispose of Contaminated Items:
   • Discard items that cannot be cleaned with bleach, such as pillows and mattresses. Clean all surfaces with soap, water, and bleach.
7. Mosquito Protection:
   • Use mosquito repellent, wear protective clothing, and use mosquito nets while sleeping to prevent vector-borne diseases in stagnant water areas.

Prevention Measures:

1. Land Use Planning:
   • Enforce land use regulations that consider flood risk, avoiding construction in flood-prone areas. Preserve wetlands and floodplains as natural buffers.
2. Stormwater Management:
   • Implement effective stormwater management systems, utilizing green infrastructure to absorb and manage rainfall, reducing runoff.
3. Flood Control Structures:
   • Build and maintain flood control structures like levees and dams to manage river and coastal floodwaters. Regular inspections and upgrades are essential.
4. Flood Insurance:
   • Encourage residents in flood-prone areas to obtain flood insurance covering material and structural damage to reduce financial losses.
5. Elevation and Resilient Building Design:
   • Construct buildings at higher elevations above expected flood levels. Use flood-resistant materials and construction techniques in flood-prone regions.

Types of Floods

Floods can be categorized into different types based on their causes, sources, and characteristics. The following are some common types of floods:

• Coastal Flood: It occurs when a number of elements, frequently including the ocean or other significant bodies of water, combine to inundate normally dry land areas along the coastline. It factors can lead to coastal flooding, which presents serious dangers to ecosystems and human populations alike. example: Deaths and serious injuries, destruction of property, evictions, and harm to the environment.

• River floods: They happen when a river’s water levels rise above their typical levels and spill over onto nearby land. It is a regular and natural occurrence that is frequently brought on by a confluence of elements like storms, excessive precipitation, snowmelt, or a quick thawing of ice and snow. For instance: a lot of rain, melting snow, ice jams, and storms.

• Groundwater flooding: It is the result of the water table rising to the surface or very close to it, which inundates the ground and may flood neighboring areas. It are caused by the saturation of soil and the emergence of water from the earth itself, as opposed to river floods, which are caused by rivers or streams overflowing. For Instance: consider the following: a high water table, heavy rainfall, impermeable soils, and property damage.

• Drain or sewer flood: This happens when stormwater drains or sewage systems are unable to handle their full capacity, which causes water to overflow into roads, properties, and other locations. Heavy rains, storms, or an abrupt surge of water that the drainage infrastructure is unable to manage are frequently linked to this kind of flooding. As an example, consider urbanization, obstructions, and heavy rainfall.

• Flash flood- An intense and confined burst of heavy rainfall characterizes a flash flood, which is a sudden and rapid onset of flooding. Flash floods are notorious for their speed and force and can happen minutes or hours after a significant downpour, frequently with little to no warning. Because of their abrupt beginning and the rate at which water levels rise, these floods are extremely dangerous. Numerous physical locations, such as cities, mountains, canyons, and other terrains, are susceptible to flash floods. example- Topograhpy, intense rainfall, rapid onset.

Conclusion on Floods

Floods are natural disasters of significant concern, with the potential to cause devastating impacts on communities and ecosystems alike. The consequences of flood include loss of life, damage to property, and long-term economic and environment repercussions. Climate change is exacerbating the frequency and severity of floods, underscoring the urgency of mitigation and adaptation efforts. Effective flood management strategies involve a combination of early warning systems, infrastructure improvements, and community preparedness. Furthermore, international cooperation is essential to address transboundary river basins and global flood risk reduction.

FAQs on Floods

What is a flood?

A flood is an overflow of water onto normally dry land. It can result from various factors such as heavy rainfall, snowmelt, storm surges, or the failure of dams or levees.

What causes floods?

Floods can be caused by natural events like heavy rainfall, hurricanes, tsunamis, or rapid snowmelt. Human activities such as deforestation, urbanization, and poor land-use planning can also contribute to flooding.

How might floods affect a community?

It is large-scale damage to houses, infrastructure, and crops can result from floods. They could lead to fatalities, population displacement, traffic jams, and contaminated water supplies.

Are all floods the same?

No, floods can vary in scale and type. They can be flash floods with rapid onset, riverine floods caused by rivers overflowing, coastal floods due to storm surges, or urban floods resulting from poor drainage in urban areas.

What precaution steps can be taken during flooding?

Follow weather forecasts and alerts regarding flooding. Keep an emergency supply kit on hand, plan your evacuation, and know how high your home is above surrounding bodies of water.

How do floods get quantified?

Maps of floodplains, river gauges, and rain gauges can all be used to determine how severe a flood is. These technologies are used by agencies to track and forecast flood events.