Basically, a dam is a barrier that prevents or restricts the flow of water or groundwater. Dams have been used for agricultural, industrial purposes, and domestic use for thousands of years. In this graphic article, we’ll consider different ways dams and reservoirs help achieve economic, environmental, and energy goals. Finally, you’ll be able to decide if their impact is worth the gain.

Dams and reservoirs have four main functions:


Irrigation refers to the process of getting water for crops to meet their water needs. Most importantly, it provides water for the growth, development, germination, and other needs of plants. In fact, nearly 30-40% of the irrigated croplands get their water from dams. There’s a problem though. Recently, studies show that irrigation dams typically fail to reach the needed amount of water.  This is due to engineering mistakes and problems. Despite this however, irrigated areas have increased from 70% to 100% for the past ten years.


These dams can collect gravitational energy to make some of the needed electrical power. In fact, around 19% of the electrical power supply worldwide comes from hydroelectric dams.

Most hydroelectric power production comes from the energy of flowing water. Basically, the water drives turbines and generators. So, the power is made from the water current.


Most commonly, dams create reservoirs by forming big natural or man-made lakes. Then, our homes and factories can use the stored reservoir water.  However, the water first needs to go to a special treatment plant.  Finally, water treatment plants make the water safe for drinking.


Reservoirs prevent downstream flooding. Basically, they stop flooding by maintaining and regulating the water flow during floods. Additionally, they also balance water flow based on weather conditions. Also, reservoirs can hold water back during heavy rains and release more during a dry spell.


Dams and reservoirs are created to provide a benefit to people.  Unfortunately, they can also have a major impact on our environment. People that live close to dams are especially impacted.

Environmental Impacts include:

Changing Aquatic Ecosystems

Building a dam in a river leads to vast changes in aquatic ecosystems. The worst outcome is habitat loss.  Habitat loss is the biggest cause of extinction. Also, reservoirs can change the chemical balance and temperature of a body of water. These changes can make it less suitable for certain fish. Eventually, this can lead to the loss of some fish species.  Changes in the ecosystem can also make it easier for predators to easily reach fish.


Dams and reservoirs can decrease the biodiversity of an area. As the flow of water decreases, sedimentation increases. Sedimentation is when particles that would normally flow through an area get caught in one place.  Then that sediment settles in the water. Sediment can bury rock beds where fish lay eggs or cover up other important food and habitat features.

Greenhouse Gas Emission

The reservoirs cause rotting vegetation in the water. This causes decomposition. Decomposition causes greenhouse gases, methane, and carbon dioxide.


Open surfaces of the reservoirs speed up water loss by the evaporation process. Generally, much more water is lost from reservoirs than is lost from the flowing rivers they replaced. Furthermore, increased evaporation can affect the microclimate and ecosystems of an area.

Seismic Activity

Did you know that large dams can trigger seismic activity? That is to say, they make earthquakes. This is due to changes in the stress of the weight of water, or increased groundwater pressure that decreases the strength of the rock under the reservoir. In short, the changes in water levels can make the bedrock unstable.


Forces People to Move

displacement of people population

Dam and reservoir construction causes serious social problems. Above all, is population displacement. Recently, an estimated 80 million people worldwide were forced to move due to dam projects. Unfortunately, these people are rarely paid for their losses of housing or the for the cost to relocate.

Human Health Risks

Health risks Human health risks

Reservoirs are an ideal breeding ground for parasites, especially mosquitoes. Overall, these parasites spread disease to nearby areas and can create serious health problems.


  • Before building a dam, we need to check how it will affect nature and plan ways to lessen the damage. We can also help restore damaged ecosystems by planting trees or making special structures to help fish swim past the dam.
  • If people have to move because of the dam, we should give them money or help them find new jobs so they’re not hurt by the change.
  • We should let everyone have a say in deciding whether or not to build a dam, and how it’s managed afterwards.
  • We need to make sure dams are safe and well-maintained so there’s no risk of accidents that could harm people or nature.
  • We can also look for other ways to make electricity besides big dams, like using windmills or solar panels.

Helpful Teaching Resources:

Other Recent Posts:

  • what is habitat conservation

What Is Habitat Conservation

Comments Off on What Is Habitat Conservation

WHAT IS HABITAT CONSERVATION? Habitat conservation means protecting the places where things on earth live.  A habitat is a place where a certain animal, plant, or other living thing lives. These places are [...]

  • sick building image

What Is Sick Building Syndrome?

Comments Off on What Is Sick Building Syndrome?

WHAT IS SICK BUILDING SYNDROME? Sick building syndrome is a term that describes a wide range of undefined symptoms that people have when they live in a building. It is mostly because of [...]

  • What Is Hydrology

What Is Hydrology?

Comments Off on What Is Hydrology?

WHAT IS HYDROLOGY? Hydrology is the study of water from a scientific standpoint. It includes the study of water's occurrence, properties, circulation, and distribution on, beneath, and above the earth's surface. Hydrologists are [...]

  • define ocean acidification

What Is Ocean Acidification?

Comments Off on What Is Ocean Acidification?

WHAT IS OCEAN ACIDIFICATION? Ocean acidification is the process by which the ocean absorbs carbon dioxide from the atmosphere, thus decreasing the ocean’s pH. The ocean absorbs up to one-third of the carbon [...]

  • what is the wildlife trade

What Is the Wildlife Trade?

Comments Off on What Is the Wildlife Trade?

WHAT IS THE WILDLIFE TRADE? It is called the "wildlife trade" when people trade and sell living or dead wild animals and plants. This practice has a direct effect on biodiversity and also [...]

  • Why corals are important

Why Are Coral Reefs Important?

Comments Off on Why Are Coral Reefs Important?

Why Are Coral Reefs Important? At first look, you may think you’re looking at a lump of colorful rocks. But, these are not rocks. These eye-catching figures are coral reefs! Found in oceans [...]

  • ocean dead zone

Ocean Dead Zones

Comments Off on Ocean Dead Zones

Ocean Dead Zones The ocean is an important part of our ecosystem. It produces most of the oxygen we breathe. It’s also very important for our economy, providing food for many people around [...]

  • walking outside and fitness

Walking for Fitness

Comments Off on Walking for Fitness

Walking is an excellent way to stay fit and healthy. In fact, walking has been proven to be one of the best ways to lose weight because it burns calories. It also helps [...]

  • What's Avian Flu

What’s Avian Flu?

Comments Off on What’s Avian Flu?

What is Avian Flu? Avian flu, also known as avian influenza or bird flu, is a viral disease that primarily affects birds. The virus can be transmitted between different species of birds, but [...]

  • what is carbon absorption

What is Carbon Absorption

Comments Off on What is Carbon Absorption

What is Carbon Absorption? Carbon absorption, or carbon sequestration, is the capture and storage of carbon dioxide (CO2) from the atmosphere. This process occurs naturally through photosynthesis in plants and algae, which absorb [...]

Have a Topic Suggestion ? We are Open to New Ideas!