Dams are among the most vital infrastructures in human civilizations. Used to store and channel water to the people in need of them, they hold a lot of space in our natural environment. But even as we celebrate the power of running water in urban areas and efficient irrigation in agricultural lands, there lie many grim realities about dams.
Dams are the most contentious development interventions, says Dr. Robert Lepenies, speaker of the working group water social science at Helmholtz Center for Environmental Research UFZ. Their economic, social, and environmental consequences are mostly not factored in when they are planned and constructed.
So yes, the title of this article, “The Damning Dark Truths About Dams,” should shock you and also compel you to push for better water protections and water-efficient systems in the world.
Let’s dive deeper in the world of dams.
What is a dam?
Similar to any structures that are being built, it serves multiple purposes. In this case, dams are structures built near the streams or river to mainly hold back water from its strong currents in flooding the mainland beside the ends of the river – as flooding has been the main problem, especially to houses living near the mouth of the dam.
According to National Geographic, there were several materials used in building dams. In the past, primarily clays and rocks were the primary materials that compose the structure. Meanwhile, in the modern era up to the present, people began utilizing concrete. It was said that the first dams built were through the efforts of the Mesopotamians, which operated the dam for a steady water source for the irrigation of their crops, which up to the present, dams have an essential impact on agriculture, as it allowed to grow and nurture agricultural matters.
Apart from its purpose of holding back water, dams can also be used to store water. Thus, most dams have created human-made artificial lakes, which we call reservoirs, where water can be stored for farming or household use. This is why we have water coming out from our faucets. As per research, there is always water available because of the water stored in the reservoir, thanks to the presence of the dam. Furthermore, dams are also used to generate electricity, like the famous Three Gorges Dam – the number one largest dam in the world based on its electricity production – in Hubei, China, which uses the dam for generating hydroelectric energy.
Consequently, dams were considered to be one of humans’ clever inventions. In fact, one of the oldest dams in the world, built by the Romans – Cornalvo Dam – is still existing and located in Spain.
More about the history of dams later. Let us identify the types of dams and their uses.
Types of dams
Currently being used around the world about 12 types of dams. However, recently there have been at least 21 types of dams that are currently in construction. Let me shed some light on this matter and discuss the first 12 types of dams.
This type of dam is built in a monolith curve upstream form, given its name arch. This is to transmit the major parts of the water towards abutments or the supporting ends of the dam. The advantage of this type of dam is to the joints of the masonry dam close. Located in Yalong River, a tributary of the Yangtze River, Jinping-I Dam stands at 305 meters, making it the tallest arch dam globally.
Buttress Dam consists of watertight parts which are supported by intervals downstream. It basically looks like the teeth of a comb but only with buttresses on its side. With this type of dam, there would be no problems in terms of foundation drainage. Also, it can be constructed even on weak foundations. Moreover, there are five types of buttress dams, namely: deck slab, multiple arch, massive head, multiple dome, and columnar.
Deck Slab Buttress Dam
This type of dam is constructed to smaller heights generally from 20 to 50 meters. This type is supported by the corbels of buttresses.
Multiple Arch Buttress Dam
“This type can be preferred for larger heights about more than 50 meters.” (The ConstructorsB, n.d.) Compared to deck slab, this is more flexible and stable.
Massive Head Buttress Dam
Unlike the previous types, this type of buttress dam does not have slab nor arch is provided in the upstream face, instead the buttress head is enlarged and joined with adjacent buttress head.
Multiple Dome Buttress Dam
This is almost similar to multiple arch, instead domes are constructed in place of the arches. Other than that, everything is similar with multiple arch. An example of this is the Coolidge Dam in Arizona.
Columnar Buttress Dam
For this type of dam, inclined columns support the deck slab of the dam. Accordingly, it is a modification of the deck slab. Also, it is not widely used.
A diversion cofferdam diverts a stream into a pipe, channel, tunnel, or other watercourses. Coffer dams are important because as per research, it helps protect the construction crews, materials, and equipment. It allows your materials to be ready with its contact with water.
From the root word itself, it aims to divert the water coming from the waterway towards a different watercourse. It is essential because it utilizes the water that ran off. Also, the diversion of water may be a source of groundwater recharge.
Embankment dam can be defined as a dam which was constructed by natural materials or simply, materials found nearby its construction. It is essential because it holds water back to avoid flooding. The largest earth-fill dam in the world is in Pakistan, named Tarbela Dam.
Like other types of dams, this is also constructed of concrete or masonry, which, given its name gravity, relies on its weight and internal strength for stability. The purpose of a gravity dam is to prevent the water’s pressure to further spill from the dam by only relying on its materials and its resistance against the foundation to hold off the water. The tallest gravity dam is found in Switzerland, standing tall with 285m, named Grande Dixence Dam.
A hydropower dam converts the energy stored in a water reservoir, usually placed behind the dam, into mechanical energy. As the water flows down through the dam, its kinetic energy is used to turn in a turbine. Three Gorges Dam, China, is the world’s largest hydroelectric facility.
Industrial Waste Dam
This type of dam is an embankment dam, only that it has built-in stages where to store waste products from the industrial process. There are waste products suspended on the water, and it gets stored on the built-in stages of the industrial dam.
Made up of concrete materials, masonry dams require safety assessment tools given its risk to the community that they may pose. (
A dam designed to be overtopped.
Regulating (Afterbay) Dam
This is a dam impounding a reservoir from which water is released to regulate the flow downstream.
This type of dam is an auxiliary dam built to confine the reservoir created by the primary dam. It can either be used to permit a higher water elevation or storage.
History of Dams
After covering the different types of dams, as aforementioned, we will dig deeper into the development of dams throughout human civilizations.
Mesopotamians were the first individuals to build the first-ever dam in the world – An ingenuity creation. The reason for this creation is that Mesopotamia’s weather affects the rivers of Tigris and Euphrates. Hence, they built dams to control the water level and avoid flooding – since this is one of the main reasons dams were built, apart from water storage and household use.It was noted that the first dam that was built is a gravity dam, that is made up of concrete which resists water load by means of weight.
The Egyptians built the first dam known to exist around 2950-2750 BC, called Sadd el-Kafara, “Dam of the Pagans.” It stands 37ft tall, 348ft. wide (crest), and 265ft (bottom). Egyptians are known for their superb art in terms of architecture. Hence, they make sure that the materials they use are durable and long-lasting, so the said dam was built with strong materials such as tons of gravel and stones (i.e., limestones, to resist erosion). However, it was not able to withstand the overflowing water, which opened failure for the dam. Despite its strong materials, it was not tight, the reason for the structure to erode quickly.
Mesopotamians once again built another dam [earth dam] which was the second known dam built called Nimrod’s Dam. This was built around 2000 BC in north Baghdad across Tigris. Although it is quite similar to a gravity dam, the only distinction is that it is made with soil. Once again, it was used to prevent erosion and flooding. Another purpose that is served is to divert the flow of the water and help irrigate the crops, in which successfully, the Mesopotamians were able to develop the growth of their crops very well.
During the hundred AD, Romans began discovering about civilization and built a concrete gravity dam. Hence, as the demand for materials in building stronger concrete dams, the arch dam was then explored and created. The arch dam relies on its shape for strength and support. With that, the first known arch dam called Kebar was built during the Mongol Period.
Beginning of the 17th century, Spaniards were able to create their own dam, which apparently was the superior to all civilizations. “In Don Pedro’s time only two types of dams were built, arch dams for narrow gaps where the foundations had good solid rocks or gravity dams where the site was wide and shallow.” (Yang, et.al, 1999) With this, new types of design for dams were explored and created. Thus, multiple arch dams and buttress dams were created for further purpose.
The Spanish brought the idea about buttress dams towards America as it was prevalent in their country.1849 was the year were demands for building dams were at their peak. Hence, in the 1850s, building dams were like trends that engineers and architects built, not only for water storage and prevention of erosion but because of irrigation.
Up to the present, the creation of dams became really essential as it served its long-lasting purpose that is relevant in the lives of many these days. Despite embarking towards the Modernity Period, the presence of dams is still widely relevant. Thus, building and renovating dams became in demand and no longer focuses solely on concrete and stones. People began exploring what materials to use, so dams can now be a source of energy.
Environmental impacts of dams
Contrarily, despite its good intention and significance, dams also accompany risks that may impact the welfare of the environment in general.
Release greenhouse gases
In the past, the effects of building dams were not quite an issue since most materials that were used to build were all-natural. However, with the beginning of civilization and industrialization, building and sustaining dams also heightened and improved. Most dams now work like a factory that releases unwanted gases, which only worsens the climate change. Greenhouse gases are released because of anaerobic bacteria, which breaks down the vegetation at the base of the reservoir, which would then emit carbon dioxide and methane.
How ironic it is that dams are also used for water storage, but that is not the case. Generally, reservoirs and artificial lakes have a larger surface area than the rivers and channels that feed them. In this case, larger surface gets exposed to the sun and more water gets evaporated abnormally. According to a study conducted by the European Water Association, the amount of water getting evaporated from large surface reservoirs is equivalent to the amount of water people need for about 26 days.
Additionally, dams affect the natural flow of water in the rivers. Water released downstream from dams has unnaturally high energy and very little sediment, which causes “hungry water” to run forcefully, eroding the riverbeds without sufficient sediment concentration to slow it down.
Destruction of Habitats
With dam interference with the composition of river channels also disrupts fish and bird migration. Also, dams are created with blocks, and these blocks block species from spawning or moving from one place to another and rearing locations. Moreover, given that dams these days are powered, there would be changes in the timing of the current flow, which affects the survival conditions of the species that live near there. Downstream habitats are also severely impacted by changes in salinity and oxygen levels. Its negative impact on the ecosystem is also prevalent as it traps river-borne nutrients, which then develops toxic algae blooms. “Some dams have killed off fisheries and entire aquatic ecosystems.”
Poorly maintained dams would have a harmful effect on the environment. This is why looking for sustainable and eco-friendly materials would help to decrease the production of harmful effects. At the same time, it keeps our dams in better condition.
Socio-Political Impact of Dams
As dams began emerging since the 1850s, gradually, building ones started to impact the environment negatively. People involved (i.e., international development institutions, decision-makers for dams) justify and base their decisions on population growth, economic, and social development, ignoring the rampant adverse effects it gives on the environment.
Notably, large dams are built around above 15 meters in height. Its reservoir would be less than a million cubic meters. Concerning its massiveness, the foundation of building these are of high importance. If, for instance, the foundation is not strong enough and fails and would cause erosion, the flood discharge is not less than 2000 cubic meters per second.
Pros and Cons of Dams
Throughout the history, dams played an essential role in the lives of humans. From simply preventing threats of flood, to storage of water, and now source of energy, human’s impressive ingenuity creation is indeed significant. However, similar to other inventions, there are also few disadvantages dams pose in the environment and humans.
Below are the list of pros and cons of dams:
Source of energy
Back in the days, the only use of dams is only to prevent threats of floods and storage of water. Given the simple living way back the emergence of industrialization, converting the energy released from dams into kinetic energy was not really impossible but was not really noticed.
At present, one of the important uses of dams it its ability to create hydroelectric power. Dams like Hoover and Three Gorges Dam are used to create electricity, helps in the irrigation for crops, storage for water, and of course flood prevention. Talk about hydroelectric power, hydroelectricity is one of the known alternative forms of energy. Which is brilliantly utilized these days.
Storage for water
With the creation of reservoirs usually behind the dams, humans need not to worry about water shortage because there are available or even unlimited water kept in the reservoir. Where do you think water coming out from our faucets come from? You guessed it!
Good for irrigation
This is why Mesopotamians developed with their agricultural growth because of the help of dams providing water for irrigation, which keeps their crops from drought. The presence of a dam creates a reservoir that can be used as a great water source, specifically for farm and industrial activities
Dams have been used for irrigation for centuries. It protects crops from drought so are the farmers from going hungry.
Protects the environment
Despite its quite harsh effect on the environment, it can still provide protection. Industrial Waste Dam, for example, traps waste and other hazardous materials suspended on the waters coming from industrial plants, preventing them from flowing towards the base of the dam. Some dams also have mine tailing impoundments, which help facilitate the processing of minerals in an environmentally friendly way.
Sediment Build Up
Apart from trapping waste and hazardous materials, this blockage may also result to build up of sediments, that may get trap on internal turbines. These sediments may pollute the water and disrupt the ecology of water.
Destroy the environment
Contrarily, like the aforementioned, dams have a harsh effect on the environment. “When water is diverted due to a dam, it can greatly disrupt the delicate natural ecosystem.” Some species may survive and adapt with the constant change of timing with current flow, but others may not, which would lead to the destruction of the environment. There could be a decline in fish productions, and the number of nutrients may not reach the sea and the species needing it, including humans.
Erosion can be prevented as long as the foundation of the dam is strong. However, given the climate change and further weather disturbance, the amount of water being stored in the dam may cause deep floods once the dam fails. The large reservoir at China’s Three Gorges Dam has eroded the nearby shoreline, which has led to landslides along the side of the reservoir. Nile Delta has also experienced erosion due to the reduction of sediment. The risk of disaster may also result due to erosion.
Can dams fail?
Dams can live up to some time, but it does not mean they can NEVER fail because gradually, it CAN. Talk about weak foundations, low-quality materials, and mismanagement during labor. Any factors can fail a dam. Also, time is one of the main factors. Due to the age of a dam, it can eventually fail. But what about dams that have not even reached their 10th-year mark yet, but have already failed? I got you covered.
Yes, dams were made for long-term use. However, there can be causes why a week-old dam gives up. We need to identify the reason for its failure to mitigate these things and save dams from failing earlier than expected.
Inadequate spillway design may cause water from the dam to spill. Given the strong current, depending on the time of the day, the more water that spills from the dam, the more chances it may fail. Spillways were designed to prevent water from spilling. If the design of the spillway is compensating with the water, it may spill and eventually ruin the spillways.
This is one of the common causes of dam failures, so a maintenance day is scheduled for dams and other equipment to solve any possible issues earlier.
Extreme inflow may be caused simply by the amount of energy released in the dam. But it could also be due to bad weather conditions. If it rains hard, the current of the water will flow faster than usual. With the amount of pressure from the inflow, it may cause cracking and eventually break the foundation.
Low quality materials
This does not only concern dams but also other infrastructures. Low-quality materials may seem less expensive, but the consequence of using them would really cause bigger problems.
This is why designs on any infrastructure are essential, so there are people assigned to check the design of infrastructure before approving it, assessing and testing it first, to ensure the condition of the infrastructure and the safety of the people who will be utilizing it. One mistake from the measurement would cause a great consequence.
Are dams sustainable?
Dams may seem to be a source of renewable energy and good storage for water. Many countries have communities that only rely on dams for electricity. Study shows that it could worsen the ecological and social condition. According to Cambridge Institute for Sustainability Leadership, “The study suggests that dams represent an unsustainable method of energy generation that disrupts the natural ecology of rivers, damages forests, releases large amounts of greenhouse gas, displaces surrounding communities, and disrupts their food, water, and agricultural systems.”
Dams alter the ecosystem. Although it provides electricity of some sort, it changes the ecosystem, which highly affects the condition of the environment. The ecosystem relies not only on water but sediments. Unfortunately, dams tend to trap sediments and eventually destroys the ecological state. Rivers carry sediment that feeds the fish. It provides the entire vegetation along the river. So, when you stop sediment flowing freely down the streams, you have a dead river.
Given the number of disadvantages mentioned above, it is not sustainable and may worsen the growing problem in the economy despite the other benefits of dams. It is not eco-friendly, as it alters the habitats of species and destroys the ecosystem. Sad to say, it has significant damage to the environment.
How can we harness the power of water for the common good?
Water is no longer limited as a fluid that humans take in or use to clean themselves. It also serves its purpose of renewable energy. To harness the power of water, hydropower became the most notable way of harnessing this power for the common good.
Ever since it became an alternative source of energy apart from fuel and nuclear plants, this is why it is stored in dams and flowing rivers to create electricity in hydropower plants. To do this, the falling water is responsible for turning on the blades of a turbine that is connected to a generator, which then converts the mechanical energy into electrical energy. Yes, hydropower is not entirely okay for the environment, but it has several advantages on why this is the best way to support the power of water.
Its advantages include:
- No burn fuels are used
- Tested and proven
- It is renewable
- The key that needs to run the power plant – water – is natural and easy to find
- It does not produce pollution
And even though it may sound perfect, it is not. Hence, here are few disadvantages of hydropower:
- May cause too much flood if not maintained well
- Changes the quality of water
- Loss of habitats for species living near the rivers
- Displacement of location by the people, as flood threats are still possible and erosion
Instead of just building dams, we need to protect rivers, invest in reforestation and work together to keep our waterways clean and flowing well.