Impact of Floods on the Environment and Humans

Floods are devastating to the environment and ecosystems in the affected region. They have a direct impact on humans, social life, the economy as well as the ecosystem. Floods have negative and positive consequences and vary based on area, depth, time and water speed. Here are the collective impacts of floods on the environment.

Erosion and Sedimentation

High-speed flood water causes riverbank erosion. Developed and urban areas become the most affected in this case. Sedimentation clogs rivers and reduces the storage capacity for wetlands and dams. Flood water carries a vast quantity of sediments leaving behind deposits after the water recedes. If the impact is extreme, floods reduce water quality, affect industrial use and the supply of water to humans.

Destruction of Property

Floods lead to the destruction of property in developed areas where humans reside. That could be in urban areas and plains. The supply of essential services like drinking water, electricity, and transport become interrupted. In many properties, floods clog different households with water, and in worse conditions, floods sweep them away. If your items in the house are affected by floods, you can check for better deals to replace the worn-out items. That is because you are likely to need to replace household items after the devastating consequences of flooding.

Dispersion of Debris and Pollutants

You will find debris, nutrients, plastics, and different pollutants in floodwater. Contaminants such as pesticides, bacteria, and chemical reagents diffuse, quickly reducing water quality. The most common debris found includes stones, trees, and pieces of destroyed property that end up affecting the natural habitats of marine species that reside in rivers and seas.

Injuries and Death

Floods lead to injuries and death among humans and livestock. The number of those affected depends on the magnitude of the flood, and the total population living in those regions determine fatalities. Highly populated areas are likely to report more cases than low populated areas. Slow-rising riverbank floods allow people to relocate to safe areas and minimises the number of casualties. However, flash floods are likely to take people by surprise, increasing the number of fatalities.

The Dust Bowl

In 1930s, the Dust Bowl occurred and greatly devastated the Midwest. There were four waves of drought that hit North America, spanning from 1930 to 19940. The drought effects were worsened by poor farming methods. Crops were destroyed and soils were left bare. When winds blew, huge clouds of dust were raised, and mounds of dirt covered everything, including houses. The dust caused suffocation in animals and pneumonia in children. This was not all as the storm worsened and the dust was blown to Washington D.C. It worsened the Great Depression and affected land productivity in the United States.


Weather patterns of the Pacific and Atlantic oceans changed 1930. The changes in weather caused the Atlantic to grow warmer and the Pacific became cooler. As a result, the air current that carries moisture towards the Great Plains from the Gulf of Mexico changed and the jet stream was weakened and its direction changed. Reaching the Rockies, the current dumped the rains, leading to the creation of tornadoes. The rain failed to reach the Great Plains when the jet stream moved south causing the drought.

Besides the change in weather, farmers also contributed to the occurrence of the drought. They cleared the tall prairie grass that covered 5.2 million acres in the Midwest, which used to protect the top soil. Since the land was bare, the remaining top soil was blown away by the strong winds. Parts of Midwest have not yet recovered from the ordeal.

The drought was worsened by the growing dust, which caused the sunlight to be reflected back into space before it could reach the earth. This caused the land to cool since the temperatures dropped. At the end of it all, the less moisture was not enough for the clouds to create enough rains.

Soil Pollution

Soil pollution occurs when harmful substances like chemicals are deposited in the soil. When these substances are deposited in excess amounts, the soil becomes alkaline in nature. Alkaline soil is often unfit for growing plants and directly affects animals and humans who consume the plants. Soil pollution is a big problem, especially in developing countries.



Chemicals are used in agriculture with the aim of increasing yields, preventing the growth of harmful herbs or killing pests and harmful fungi. The purpose for chemical use is very genuine but the side effects are felt by plants, animals and human beings. Since fertilizers and farm chemicals are not organic in nature, they don’t decompose with time. As a result, the chemicals end up seeping into the ground, and polluting the soil and ground water. Others are excessively absorbed by plants, making them toxic and unfit for human consumption.

Industrial Wastes

Industries produce large amounts of toxic wastes, which are often released into the environment. Several measures have been put in place to help manage industrial wastes, but it is still one of the leading causes of soil pollution. Improper waste disposal from industries has raised an alarm and a lot needs to be done to prevent the havoc caused by these wastes.

Human Wastes

We play a major role in causing soil pollution through our daily activities. Domestic wastes released from our households pollute the soil. Additionally, sewage leakages also end up on the land, causing pollution. Proper human waste disposal and management should be done in order to avoid this kind of pollution.


Deforestation occurs when trees and other vegetation are cut down without being replaced. This exposes the soil to various agents of erosion. The bare land exposes a lot of soil to the already contaminated air, causing soil pollution, as the trees that act as wind breaks have been cleared.

Effects of Soil Pollution

There are various effects of soil pollution that affect the entire ecosystem. The impacts are massive and affect human and plant life. They include:

  • Increased cases of diseases caused by consuming foods that have been grown on contaminated soil
  • Climate change, which causes global warming, leading to the disruption of the ecosystem.
  • Reduced soil fertility, which leads to low agricultural production

The 1911 Jiangsu-Anhui Flood

The Yangtze River is 3,917 miles long, and it is the third longest river in the world. It flows throughout China, and it is the country’s primary source of irrigation and transportation. Unfortunately, in 1911, heavy rainfall simultaneously raised water levels of the rivers Yangtze and Huai to a dangerous point, causing the Jiangsu-Anhui flood.

Consequences of the Flood

The floods claimed the lives of about 100,000 people, and lots of properties were lost. The people of Eastern and Central China faced starvation because their crops were washed away by the floods. An estimated 30,000 square miles of land was flooded forcing millions of people to become refugees. To top it all, crimes and riot cases were on the rise due to food shortage. Food was costly and limited in supply, leading to famine. At the end of October 1911, grain prices were above normal, ranging between 80 to 100%. Therefore, one million people in northern Jiangsu and other more than a million in Anhui went through mass starvation. This meant that the survivors who required relief food at the beginning of 1912 were close to 3 million.

The North American Drought of 1988-1989

The 1988-1989 drought affected 45% of the United States. It became one of the worst droughts that ever occurred in North America. In some areas, the biting drought was felt up to 1990. The blowing dust covered almost everything, causing some schools to be closed down, especially in South Dakota. When spring came, many weather stations recorded very low monthly data on rainfall.


Various devastating effects were felt by both people and animals. Starting with the forest fires, they consumed 793,880 acres of Yellowstone National park. The park was closed for the first time in history. To top it all, 4800-17,000 people succumbed to death as a result of the heat waves of the drought. The scorching effects of the drought were felt in the North West, the Northern Great Plains and the West Coast as revealed by NCDC. Besides that, the drought cost the U.S government an estimated $39 billion, according to NCDC. It was therefore ranked as the most costly in the history of the United States, despite the fact that it covered a relatively smaller area, compared to the Dust Bowl, which affected 70 percent of the country.

The 2012- 2013 North American Drought

During the winter of 2011-2112, North America experienced one of the worst natural calamities of the modern era. Strong positive Atlantic and Arctic oscillation pushed winter storms from away from the United States in what would result in the drought. When spring came, there was less snow so the ground did not get enough moisture. Less evaporation occurred leading to low rainfall. Dry conditions were noticed within a short time since there was very little snow that melted. To worsen the situation even more, weak tornadoes were experienced and were later followed by stronger ones in the month of March 2012. Drought conditions increased as rainfall decreased.

In Summer, things moved from the frying pan into the fire. This was because the strong heat waves in North America increased the evaporation rates of water sources, meaning that that the soil was left with no water. With no moisture, enough rain could not form, and when June 2012 came, strong storms caused only little rainfall. Any rain water that would have saved the situation ran off quickly since the soils had been hardened by the droughts. In the long run, numerous death were reported and properties of an unknown value were destroyed. This was a big tragedy indeed.

Water Pollution

Water pollution occurs when untreated waste substances or chemicals are released into water. When polluted water is consumed, it affects the health of plants, animals and human beings. The use of chemical fertilizers in agriculture, such as pesticides, herbicides and insecticides, to control pests and disease in farms causes water contamination, when surface runoff occurs. Wastes from factories, especially raw sewage, heavy metals like lead and mercury cause contamination when discharged into water bodies. Millions of people have been affected all over the world because of consuming polluted water and other food products that have been contaminated by polluted water.

Causes of Water Pollution

Waste management process has not been fully taken into consideration worldwide. Waste disposal and recycling methods are still a big challenge to many nations. Some commonly known sources of water pollutants which include:

  • Agricultural chemicals like herbicides, insecticides and pesticides
  • Domestic wastes
  • Detergents and fertilizers
  • Industrial effluents

Typically, these harmful pollutants and by-products are directly released into water sources leading to contamination. Others like farm chemicals are washed down into water bodies or percolate the soil into the ground, causing contamination to ground water.

Effects of Water Pollution

Diseases: Various water borne diseases affect humans when they take or consume polluted water. The disastrous health effects are felt by both the young and the aged. Diseases like typhoid, hepatitis, cholera are easily spread by taking contaminated water.

Eutrophication: Hazardous chemicals and metals in water bodies encourage the growth of algae. These aquatic plants are food for certain bacteria which are known to reduce the amount of oxygen in the water. The algae form layers in the water and affect other aquatic lives due to reduced circulation of oxygen in water.

Destruction of ecosystems: Ecosystems comprise of both the flora and fauna. They are often affected whenever the environment is altered in a negative way. Water pollution destroys the entire ecosystem’s food chain if it is not kept in check. An unbalanced ecosystem cannot be self-sustaining, and this could mean extinction for some species.


Water and sewage treatment measures should be put in place to reduce water pollution. Wastes from industries and households should be treated before they are released into water bodies.

It’s high time people should consider using environmentally friendly products with less or no toxic content. We’re not saying that these measures are not being implemented, but some kind of reinforcement is needed to lower water pollution even more.

Air Pollution

Air pollution refers to the contamination of air through the release of harmful dust particles, smoke or gases from factories, households, vehicles etc into the atmosphere. This occurs when the air in the atmosphere is altered, chemically, physically or biologically. The alteration makes the air dirty and unfit for humans, plants and animals.



During mining, various equipment are used to carry out different activities like drilling, excavating, blasting of rocks, among others. These activities release dust, smoke and even chemicals into the atmosphere, causing massive air pollution. These pollutants affect the health of miners and people living around mines.

Burning of Fossil Fuels

When fossil fuels, such as petroleum and coal are burned, sulfur dioxide, which is a harmful gas, is emitted into the atmosphere, causing air pollution. Polluted gas and smoke emitted from cars, trains, trucks and airplanes that we often use as our means of transport also contribute to air pollution. Other gases like carbon monoxide released as a result of incomplete fuel combustion and nitrogen oxides produced during our daily activities, such as when burning garbage and from untreated waste materials released from factories also cause air pollution.

Agricultural Activities

Hazardous gases like ammonia are often released from fertilizers used in agriculture. The frequent use of pesticides, insecticides, herbicides and other farm chemicals also pollute the air. These products also cause water pollution when they are washed into water bodies during rainy seasons.

Exhaust from Factories and Industries

Manufacturing is one of the biggest and fastest growing sectors in the world. Large amounts of untreated gases that are released into the atmosphere like carbon monoxide, nitrogen, and sulfur are very dangerous to human and plant life. Chemical wastes, organic compounds, and hydrocarbons that are emitted from factories and industries also affect the quality of air.

Effects of Air Pollution

Respiratory and Heart Problems

Air pollution affects millions of people. Studies have linked numerous respiratory diseases, such as pneumonia and asthma, to air pollution. Increased cases of cancer and heart conditions have also been reported across the world to have affected and even cost millions of lives thanks to air pollution.

Global Warming

The adverse effects of global warming are felt in various countries, ranging from increased temperature and severe drought to increased cases of flooding, melting of icebergs and loss of natural flora. The polluted air eats up the ozone layer, exposing lives to harmful heat radiation.

Acid Rain

Acid rain forms when water droplets combine with air pollutants, such as sulfur oxide and nitrogen oxide in the atmosphere. The mixture cools, condenses and falls as acidic rain. Acidic rain is known to be corrosive in nature and causes damage to iron surfaces. It also causes serious health problems if the water is consumed by people and animals.

Vietnam’s 1971 Red River Delta Flood

Vietnam is located in Southeast Asia. It experiences a monsoonal climate season in the north. The season is always hot and rainy and runs from May to September. The capital city of Vietnam is Hanoi and it’s located in the Red River Delta of North Vietnam. The river has three major tributaries, namely, Thao, Lo and Da. Flooding occurs from June to October in Red River Delta, although serious flooding occurs in August when water levels are between 13-20-feet high above the ground.

Vietnam’s capital is protected from flooding by the dikes, which were built 1000 years ago. The dikes were regularly maintained to ensure they remained in good condition. Reservoirs were also built upstream in order to establish flood retention and diversion to help prevent the capital from flooding. However, the 1971 Red River Delta flood occurred at a time when Vietnam War was taking place, and the country was under US military action. Although the flood was overshadowed by the military action in the country, it was one of the worst natural disasters in the history of Vietnam. The floods affected the North Vietnam community and killed at least 100,000 people. Heavy rains likely caused the dikes to overload resulting in flooding.

The Chinese Floods of 1931

China is one of the oldest civilizations built near rivers. This was mainly because the rivers provided food (especially fish), fresh drinking water, hiding places during war attacks and water used for farm irrigation. Flooding was common in many of China’s oldest cities, and this has been happening throughout the Chinese history. However, there came a year when the floods were a wonder. That year was 1931. China’s three biggest rivers, the Yangtze, Huai and Yellow, all flooded that year. This was one of the worst floods ever recorded in history, since it killed between 1 to 4 million people in the country.


People have lived along the Yangtze, Yellow and Huai rivers for many centuries. Several reasons led to the flooding of these rivers. Starting with the weather, the long drought that occurred from 1928-1930 greatly affected China. The lack of rain during that period caused soils to dry up and made the rivers shallower. Winter then followed in 1930, which saw big snowstorms hit the country. It was then followed by extremely heavy rains in that filled the the country’s three rivers, during the spring. These rains caused the remaining snow to melt and the water volume increased in the rivers. To top it all, the Pacific Ocean currents occurred in the same year, causing 2 strong cyclones to hit China. In July 1931, China was again hit by another series of cyclones, and this month was unprecedentedly, since a total of 7 catastrophic cyclones were experienced a span of one month.

The radical changes in weather partially contributed to the flooding, but before the floods, modern farming techniques had been embraced in China so as to increase agricultural production. There was political instability in the country, thanks to wars and rebellions. This hindered the process of monitoring the rivers since the government programs were responsible for this task. As a result, the land close to the rivers was overused. Forests and wetlands were destroyed. The dams and dikes that were supposed to control the water in the rivers were wrongly built. All these caused the raging waters to break dams and river banks, leading to flooding.


When the three rivers flooded, 145,000 people died, according to Chinese sources. Western sources, on the other hand, recorded the death toll to be between 3.7- 4 million. The hazardous floods caused people to die due to waterborne diseases like typhus and cholera. Many others died due to starvation. On August 19, at Hankou town in Wuhan, the water level exceeded 16 meters. This was the climax of the floods, and 200,000 people drowned at night. This occurred near lake Gaoyou when water rushed through the Grand Canal and washed away dikes.