17 Effects of Flooding on the Environment (Positive & Negative)

The effects of flooding on the environment cannot be overemphasised. From affecting our surroundings including plants and animals, flooding has a deleterious effect on humans causing communicable diseases most especially to children of which the end product can be death.

Flooding, believe it or not, is the deadliest form of extreme weather. There’s probably a lot you don’t know about floods and flooding. Floods are the most common natural disaster, and they occur when a large amount of water overflows and submerges normally dry terrain.

In coastal areas, floods are frequently produced by heavy rainfall, quick snowmelt, or a storm surge from a tropical cyclone or tsunami. Floods may wreak havoc on communities, causing death and damage to personal property as well as important public health infrastructure.

Floods impacted almost 2 billion people worldwide between 1998 and 2017. Floods are most dangerous to those who live in floodplains or in buildings that aren’t flood-resistant, who don’t have flood warning systems or who aren’t aware of the danger.

Floods, droughts, tropical cyclones, heat waves, and severe storms have caused between 80 and 90 per cent of all reported natural catastrophes in the last ten years. Floods are becoming more frequent and intense, and extreme precipitation is anticipated to become more frequent and intense as a result of climate change.


What is Flood?

A flood is a water that overflows and submerges normally dry terrain. They are by far the most prevalent natural occurrence of severe weather. Floods can take on a variety of shapes and sizes, ranging from a few inches to many feet of water. They might also appear suddenly or gradually. To better address the topic “What is a flood?” we’ll explain what each type of flood situation is.

There are five types of floods, according to the National Severe Storms Laboratory.

They are as follows:

  • River Flood
  • Coastal Flood
  • Storm Surge
  • Inland Flooding
  • Flash Flood

As the list above indicates, flooding can occur everywhere, including both coastal and inland areas.

Let’s take a closer look at the many sorts of flooding.

1. What is a River Flood?

River flooding is the first sort of flooding we’ll look at.

What do we mean by river floods?

When water levels rise above the tops of river banks, a river flood occurs. This type of flooding can occur in any river or stream channel. Everything from streams to the world’s largest rivers falls into this category.

River floods can occur quickly or gradually. Smaller rivers, rivers with steep valleys, rivers that travel for a large portion of their length through impermeable terrain, and generally dry channels are more prone to sudden river flooding.

Low-rising river floods, on the other hand, are more common in major rivers with huge catchment basins. A catchment area is any area of land where rainwater collects and drains off into a common outlet, in case you didn’t know.

2. What is a Coastal Flood?

A coastal flood occurs when seawater inundates normally dry land areas along the shore.

3. What is a Storm Surge?

Storm surge is an unusual rise in water level in coastal locations that is greater than the astronomical tide. Storm surge is a particularly hazardous type of flooding. It has the potential to flood extensive coastal areas at once. It can also swiftly produce flooding. When a storm surge coincides with high tide, extreme flooding occurs.

Storm tides can reach over 20 feet as a result of this. Storm surge is the most deadly feature of any tropical system, according to meteorologists. It is the most dangerous to both people and property. We’ve seen very disastrous storm surge consequences in the past. During Hurricane Katrina, for example, the storm surge killed nearly 1,500 people (directly and indirectly).

4. What is an Inland flood?

Inland flooding is sometimes referred to as urban flooding by some organizations. Inland flooding can also take the form of a flash flood. Flooding that occurs inland, rather than along the shore, is known as an inland flood.

Coastal flooding and storm surge are not, therefore, inland floods. Because there is nowhere for the water to go, inland floods are generally severe in metropolitan areas.

The following urban characteristics might cause urban flooding or exacerbate inland flooding:

  • Paved roads and streets
  • Low-capacity drainage equipment
  • Dense buildings
  • Low amounts of green space

5. What is a Flash Flood? 

A flash flood is the most well-known and devastating type of flood. Flooding that occurs within 6 hours, and commonly within 3 hours, of significant rainfall, is known as a flash flood (or other cause).

How Does Flooding Occur?

Floods are one of the most common natural disasters, but they are also among the most fatal and devastating. A human can be knocked down in 15 cm of water, while a car can be moved in 60 cm. Floods occur when there is nowhere for extra water to go. They’re worst when there aren’t enough drains in the area, but even complex stormwater systems can be overwhelmed by a large amount of rain in a short period of time.

Drought-stricken areas are even less able to cope with heavy rainfall, despite the fact that they are exactly what they require. The water-holding lakes or rivers might also become excessively full, causing them to overflow.

If the earth is too moist to absorb the excess water, a flood develops, resembling a large puddle. A regular puddle will gradually sink into the ground, but during a flood, puddles have nowhere to go, therefore they continue to expand and grow.

Floodwaters can sometimes cover roads, cars, and even houses. During a flood, everything looks different; it’s as if there’s a new pond or lake. You can also tell which parts of a town are taller and which are lower.

The high spaces jut out like islands into the sea, while the low spaces are fully submerged. Even after the rain stops, the floodwaters might take days or weeks to recede. However, it gradually soaks into the earth or evaporates and dissipates into the atmosphere. The flood will then be ended.

Major Causes of Flooding

As we mentioned above, there are plenty of different causes of flooding. While different flood types typically have different causes, most floods are caused by one of the following activities.

  • Heavy Rainfall
  • Overflowing Rivers
  • Broken Dams
  • Storm Surge and Tsunamis
  • Channels with Steep Banks
  • A Lack of Vegetation
  • Melting Snow and Ice
  • King Tide

1. Heavy Rainfall

Flooding can be caused by a variety of factors, the most common of which is heavy rainfall. When there’s too much rain or it comes down too quickly, there’s nowhere for it to go. Floods, such as flash flooding, can occur as a result of this. Heavy rainfall is the most prevalent cause of riverine and flash flooding.

Rivers take thousands of years to create. Every river is unique, and it forms in reaction to the following factors and they include the average quantity of local rainfall and runoff, the geography, vegetation, and soil types of the area.

With the exception of rainfall, these characteristics remain generally stable over time. Rivers have a maximum carrying capacity. Rainfall is higher than usual, resulting in a higher runoff. Because the river channel cannot carry this runoff, it spills over onto the land.

2. Overflowing Rivers

Floods can also be caused by overflowing rivers. However, large rains aren’t required for river flooding to occur. River flooding can occur when there is debris in the river or dams that prevent the water from flowing freely.

3. Broken Dams

Flooding can also be caused by broken dams. When heavy rains fall and water levels rise, older infrastructure can crumble. Dams failed, releasing torrents of water on unsuspecting residents. When Hurricane Katrina slammed New Orleans in 2005, this was part of what happened.

4. Storm Surge and Tsunamis

Flooding is also caused by storm surges and tsunamis. Storm surge is a rise in seawater level above usual along a shore induced by a storm. Hurricanes and other tropical systems can cause sea levels to increase, burying previously dry coastal communities under several feet of water.

Tsunamis, on the other hand, are massive waves triggered by earthquakes or volcanic eruptions beneath the sea. As these waves move inland, they gain height and have the potential to send a large amount of water inland in coastal areas. Strong onshore winds are common during storms, which is caused by low air pressure.

Tropical cyclones are frequently accompanied by storm surges. A severe low-pressure system can cause a storm surge. During a storm surge, coastal flooding is likely. Furthermore, if a storm surge is combined with a riverine flood, the area and extent of flooding may be increased.

5. Channels with Steep Banks

Flooding can also be caused by channels with steep banks. When there is rapid runoff into lakes, rivers, and other basins, flooding is common. This is especially true in rivers and other waterways with steep slopes.

6. A Lack of Vegetation

Flooding can be caused by a lack of vegetation. Vegetation can aid in the slowing of runoff and the prevention of flooding. There is little to stop water from running off and overflowing river banks and streams when there is a dearth of vegetation.

7. Melting Snow and Ice

Flooding is also caused by the melting of snow and ice. When a big amount of snow or ice melts quickly, it usually has nowhere to go but low-lying places. These aren’t the only reasons for floods, but they are among the most common.

8. King tide

King tide‘ is a word used to denote a particularly high tide. The tidal cycle includes these tides, which are both natural and predictable. They happen at different times of the year depending on where you are and what year you are in. They can have a big impact where the sea meets the land, such as on beaches, estuaries, harbours, and other coastal areas.

Riverine flooding can be exacerbated and extended by king tides. Consider a town on the seaside with a river running through it. Parts of the town may be flooded if the river floods. Floodwater will have less opportunity to drain to the sea if the flood coincides with a high king tide. There’s a good chance that more of that town will be inundated, and at a higher level.

Positive Effects of Flooding on the Environment

Flooding might be regarded as a dangerous phenomenon but surely there are positive effects of flooding on the environment. the following are the positive effects of flooding on the environment.

  • Renewal of Wetlands
  • Returning Nutrients to Soil
  • Preventing Erosion and Maintaining Land Mass Elevation
  • Recharge and Replenish Ground Water
  • Flooding adds Nutrients to the Sea
  • Dislodges Accumulated Debris
  • Supplies Sediment to Deltas
  • Floods Can Trigger Breeding Events and Migrations
  • Floods Can Boost Fish Stocks

1. Renewal of Wetlands

The renewal of wetlands is one of the positive effects of flooding on the environment. Wetlands are an incredibly important environment, as they support nearly 40% of the world’s biodiversity. They operate as a carbon sink, filtering water and reducing flooding. Floods help to keep ecologically significant wetland areas healthy. Wetlands contribute to the health of water supplies and even have an impact on air quality.

Floods inundate wetlands, bringing with them more garbage. They also transport and deposit nutrient-rich sediments in wetlands, which support both plant and animal life. Flooding also contributes nutrients to lakes and streams, which aid in the maintenance of healthy fisheries.

2. Returning Nutrients to Soil

The returning of nutrients to the soil is one of the positive effects of flooding on the environment. Floods bring hazards, but they also provide nutrition and other life-sustaining elements. Seasonal floods can help ecosystems regenerate by supplying life-giving water in a variety of ways. Floodwaters transport nutrients and sediments to floodplains, which nourish the soil. They aid in the distribution and deposit of river sediments across broad swaths of land.

The nutrients in the topsoil are replenished by these river sediments, making agricultural regions more fruitful. Because recurrent flooding resulted in fertile, productive farmland, many ancient civilizations concentrated their inhabitants around the floodplains of rivers like the Nile, Tigris, and Yellow.

The Aswan High Dam in Egypt stopped the Nile from drowning major population centres downstream, but it did so at the expense of once-fertile agricultural regions along the river’s banks.

One of the most well-known benefits of floods is that it fertilizes the land. When the water recedes, fine sand, clay, silt, and organic debris are left behind. Floodplains are one of the most fruitful agricultural places on the planet because of this. As they cultivated along the Nile, ancient Egyptians were well aware of this principle.

As a result, they coined the phrase “The Gift of the Nile” to describe the Nile’s recurrent flooding. Furthermore, the flooded soil condition allows for the development of a variety of crops, including rice. To take advantage of this natural fertilization process, rice paddies are intentionally flooded. Rice is a staple meal for about half of the world’s population, and Asian communities have historically grown it in paddies.

3. Preventing Erosion and Maintaining Land Mass Elevation

The prevention of erosion and maintaining of landmass elevation is one of the positive effects of flooding on the environment. Soil deposited by floodwaters serves to avoid erosion and keep land masses elevated above sea level. The Mississippi River Delta’s rapidly retreating land is due to man-made flood controls and levees that prevent topsoil-replacing sediments from being deposited in the delta.

4. Recharge and Replenish Ground Water

The recharge and replenishment of groundwater are some of the positive effects of flooding on the environment. For freshwater, many population centres rely on groundwater and subsurface aquifers. Floodwaters soak into the earth and percolate down through the rock, replenishing underground aquifers that supply fresh water to natural springs, wells, rivers, and lakes. Floodwater does, in fact, recharge groundwater supplies.

It infiltrates the ground through aquifers where the terrain is permeable (loose rocks and sediment). This groundwater can subsequently run down rivers or emerge as natural springs on the land surface.

During dry seasons, when groundwater may be the sole source of fresh water available, ecosystems rely significantly on it. A plentiful supply of groundwater improves soil health and results in more productive crops and pasture lands.

5. Flooding adds Nutrients to the Sea

The addition of nutrients to the sea is one of the positive effects of flooding on the environment. Small seasonal floods, likewise, add nutrients to the sea. Plankton and other small organisms feed on them and multiply. They support higher aquatic food webs, including people, in this way.

6. Dislodges Accumulated Debris

The dislodgement of accumulated debris is one of the positive effects of flooding on the environment. Furthermore, the power of surging floodwater can loosen items that have become stuck in rivers and estuaries. Branches, logs, and stones commonly obstruct the flow of water in rivers. They can sometimes completely stop the flow of water, resulting in droughts downstream.

Floods can displace material that has blocked river flow, triggering droughts downstream. During the dry season, when water supplies are already scarce, this can be disastrous. Because of this, zebras, impalas, and other wildlife may succumb to thirst, hunger, and weakness. As a result, flooding during the rainy season not only fills rivers but also clears them of all undesired detritus.

7. Supplies Sediment to Deltas

The supply of sediment to deltas is one of the positive effects of flooding on the environment. Deltas arise when sediment accumulates faster than the sea can take it from rivers. They are very productive areas that also serve to protect the coast from waves and storms. Floodwaters deposit material on deltas when they reach estuaries, strengthening them.

8. Floods Can Trigger Breeding Events and Migrations

The trigger of breeding events and migration is one of the positive effects of flooding on the environment. In some species, flooding can cause breeding events, migrations, and dispersal. Thousands of water birds arrived in the Macquarie Marshes in New South Wales, Australia, in 2016. For the first time in years, flooding had inundated their marsh habitat, prompting a huge breeding event.

9. Floods Can Boost Fish Stocks

The boost of fish stocks is one of the positive effects of flooding on the environment. Small seasonal floods can assist native fish stocks to compete with invasive species that aren’t acclimated to the river’s cycles. Small fish can use the sediment deposited on riverbeds during floods as a nursery. Floodwater nutrients can help support aquatic food webs by increasing productivity.

Negative Effects of Flooding on the Environment

The negative effects of flooding on the environment are what people’s minds come to when we talk of flooding. so, with that let’s discuss some of the negative effects of flooding on the environment.

  • Loss of Lives and Property
  • Loss of Livelihoods
  • Decreased Purchasing and Production Power
  • Mass Migration
  • Floods Can Harm Wildlife
  • Floods Cause Sedimentation and Erosion
  • Floods Carry Contamination
  • Floods Spread Diseases

1. Loss of Lives and Property

The loss of lives and property is one of the negative effects of flooding on the environment. Flooding has immediate consequences such as loss of life, property damage, agricultural devastation, animal loss, infrastructure failure, and worsening of health due to waterborne infections. Flash floods, which occur suddenly and with little or no notice, kill more people than slow-moving riverine floods.

2. Loss of Livelihoods

The loss of livelihoods is one of the negative effects of flooding on the environment. Economic operations come to a halt when communication linkages and infrastructure such as power plants, highways, and bridges are damaged or disrupted, resulting in dislocation and the dysfunction of regular life for a time far beyond the duration of the flooding.

Similarly, direct effects on production assets, whether in agriculture or industry, can stifle normal activity and result in job losses. Even in non-flooded areas, the effects of the loss of livelihood can be seen in economic and commercial activity.

3. Decreased Purchasing and Production Power

The decrease in purchasing and production power is one of the negative effects of flooding on the environment. Long-term consequences of infrastructure damage include disruptions in clean water and energy, transportation, communication, education, and health care.

Increased vulnerability of communities living in flood plains is caused by loss of livelihoods, reduced purchasing power, and loss of land value. The added costs of restoration, relocating people, and removing the property from flood-affected areas might divert money that would otherwise be used to keep production going.

4. Mass Migration

Mass migration is one of the negative effects of flooding on the environment. Flooding on a regular basis, which results in the loss of livelihoods, production, and other long-term economic consequences and sorts of suffering, can lead to mass migration or population displacement. Overcrowding in cities is exacerbated by migration to developed metropolitan regions.

These migrants augment the ranks of the urban poor, and many of them find up living in low-lying areas of cities prone to flooding and other hazards. Selective labour outmigration can occasionally result in significant socioeconomic issues.

5. Floods Can Harm Wildlife

The harm to wildlife is one of the negative effects of flooding on the environment. Flooding can be harmful to wildlife, resulting in drowning, disease spread, and habitat degradation. Hundreds of animals were killed in floods that flooded Kaziranga National Park in the Indian state of Assam in 2012, including several endangered one-horned rhinos (Rhinoceros unicorns). Even aquatic life can be harmed by unpredictable floods. For example, fish can be moved and their nests destroyed.

6. Floods Cause Sedimentation and Erosion

Sedimentation and Erosion are some of the negative effects of flooding on the environment. Floodwaters can change the terrain by eroding riverbanks and causing them to collapse, for example. Sediment becomes suspended in the water as floodwaters bring material from the eroding banks, which can deteriorate water quality and contribute to toxic algae blooms.

Sedimentation is the process through which suspended material settles out of the water, clogging riverbeds and streams, suffocating aquatic species, and destroying habitats. Ecosystems that are already degraded or highly modified are more vulnerable to erosion and sedimentation.

7. Floods Carry Contamination

The spread of contamination by floods carrying contaminants is one of the negative effects of flooding on the environment. Pollutants such as agricultural pesticides, industrial chemicals, garbage, and sewage can contaminate floodwater.

If tainted floodwater reaches the ocean, it can poison the water and harm delicate ecosystems like coral reefs. After being overwhelmed with toxic floodwater in February 2019, marine biologists feared for the Great Barrier Reef’s safety off the coast of Queensland, Australia.

8. Floods Spread Diseases

The spread of diseases is one of the negative effects of flooding on the environment. Floods are the most common source of infectious disease outbreaks caused by weather. Flooding increases the risk of waterborne diseases like hepatitis A and cholera spreading.

Floodwaters receding can leave stagnant pools of water, which are ideal breeding grounds for mosquitos that can spread malaria and other ailments. Floods also increase the incidence of zoonosis (diseases that humans can contract from animals), such as leptospirosis.

Effects of Flooding on the Environment-FAQs

How do Floods Affect Animals?

Flooding puts animals at risk of drowning as well as other water-related injuries. Flood water also includes hazardous germs that can come from a variety of sources, including dead animals and trash, and disease epidemics can occur under these conditions adversely affecting animals.

Can a Water Body be Flooded?

When rain and/or snowmelt pulses migrate downstream, rivers and creeks which are water bodies get flooded. As a result, water overflows the channel’s banks and spills onto the adjacent floodplain. The amount of water and material that flows through a natural river channel shapes it.

What is the difference between flooding and run-off?

Runoff is the phase of the water cycle that runs overland as surface water rather than being absorbed into groundwater or evaporating whereas too much runoff causes flooding.


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