We all know what a dam is. But still, to recapitulate, let's cover the meaning and definition of a dam. A dam is an artificial barrier created across a river or underground streams, to restrict the flow of water. It is made of bricks, clay, concrete, and other materials. This construction helps in the retention of water flow, resulting in the formation of artificial lakes or reservoirs.

A dam not only restricts the flow of water but also presents a wide range of advantages like flood suppression, irrigation, consumption, etc. Different dam structures are made according to the needs (for example, arch dams, gravity dams, etc). But besides a humongous range of advantages, dams confer several negative externalities that have adverse impacts on the ecosystem.

In addition, by managing water flow, these lakes help in flood prevention. Lakes are necessary, yet they often have an adverse impact on biodiversity and water flow. To maintain the natural course of events, alternatives to big dams are being considered and planned. In this article, you will understand about dams, its disadvantages, and alternatives to dams. Thus, we require an alternative to big dams, which is the topic for today’s discussion- Alternative to dams.

Disadvantages of Big Dams

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Why do we need an alternative to big dams? Besides being an abode to many advantages, dams confer numerous disadvantages that make us look for alternatives.

Some of these disadvantages are listed below.

A huge amount of Human Displacements

One of the major drawbacks of constructing a dam is that it displaces a huge amount of human as well as cattle population. In the past two centuries, more than 500 million people have been displaced due to the construction of reservoirs behind a dam. The area surrounding the dam and the reservoir gets flooded frequently, and thus, the area that was previously available for numerous purposes cannot be now used for any activity including habitation, farming, or cattle-rearing.

Emission of Greenhouse Gases

When the surrounding area of the reservoir gets submerged in water, it leads to decay of the vegetation of that area. The decayed plants eventually start releasing greenhouse gases like methane, which is 20 times better reflector than carbon dioxide.

Besides, massive forest areas are also destroyed for constructing a dam. When trees are lost, the level of carbon dioxide increases in the atmosphere due to the reduced amount of photosynthesis processes.

Disruption of the Local Ecosystem

Since large areas of forests are destroyed for the construction of dams, the impact on the local ecosystem is also drastic. The dam creates a barrier in the free flow of water, which hinders the movement of aquatic animals, which is necessary for their breeding and migration, and thus, the local aquatic biome is destroyed.

Besides, rivers have certain sediments that are necessary for the survival of marine life. Lack of such sediments leads to temperature changes, imbalance in the chemical composition and shoreline stability, and much more. The riverbed also gets eroded.

Impact on Groundwater

When the riverbeds start deepening, it starts affecting the groundwater levels i.e. groundwater level starts falling. It becomes difficult for the plants to reach for water. It can also affect the mineral and salt content in the groundwater, thus, affecting the soil composition.

Adverse Effects of Big Dams

The walls of dams hinder fish migration. It separates spawning and rearing areas completely or partially. Furthermore, the sediments tapped by these enormous dams are essential for the survival of fish and other aquatic species living downstream.

Dams also have the impact of transforming a free-flowing river or stream ecology into an artificial slack-water habitat. Sudden changes in temperature, oxygen levels, water chemical composition, and other factors can have an adverse influence on a variety of species.

Because of this rapid change, aquatic animals that evolved in a certain habitat may face extinction. Furthermore, these reservoirs usually harbour a variety of exotic and non-native species, which harms a river's regular ecosystem. As a result, the demand for an alternative to large dams is only logical if such ecosystems are to be saved.

Aside from the ecosystem of rivers, these dams have a significant environmental impact on the lives of those who live near them. The total environment surrounding a river is affected by changes in its flow and sediment transportation.

As the adverse effects of large dams have become more apparent, the need for alternatives has increased.

Finding an Alternative to Big Dams

Seeing the above-mentioned disadvantages conferred by big dams, we can conclude that dams are a great way for channelizing water to several uses, but not the best. Humans are not the only species on the earth. We coexist with other species. But with dams, we are, intentionally or unintentionally, destroying the natural regimes of other coexisting species. Thus, we need to search for an economically, socially, and environmentally feasible alternative to big dams for reducing their adverseness.

Some alternatives that can replace or reduce the need of constructing Big Dams are given below:

Recycling/Reuse of water: One of the ways of doing so is reusing or recycling the water. By recycling or reusing, we mean the process of sewage treatment. Sewage treatment plants can put the sewage or grey water into use again and thus, helping in meeting the water supply for non-portable purposes like industrial processes, irrigation, toilet purposes, etc.
Groundwater Recharge: Groundwater recharge or deep drainage is the process of replenishing the groundwater level of an area during rains. When talking about sandy soil, it takes just 2 days for the water to percolate through the soil and thus, is the quickest way of replenishment.
Reworking on the existing Dams: Instead of constructing new dams, the authorities can focus on increasing the capacity, opening newer channels, and putting existing dams to several other features. And for sure, increasing the capacity of a dam is much cheaper than constructing a whole new dam (economically, socially, and environmentally).
Flood Management Alternatives: Dams have a crucial role in flood management. But there are several other ways of flood management, such as reducing water run-off, Riparian and in-river flood management, separating the people and the threat, etc.
Energy production Alternatives: Dams also have a vital role in hydroelectricity production. But with the amount of adverseness it confers, we need to search for other alternatives to it. Some alternatives to reduce the damage caused by dams are efficient end-use, the use of newer technologies like solar energy, thermal energy, etc.

Solved Examples

1. Explain the alternatives to energy production and flood management uses of dams.

Ans: Dams play a crucial role in flood management. But there are several other ways of flood management, such as reducing water run-off, Riparian and in-river flood management, separating the people and the threat, etc.

Dams also play a vital role in hydroelectricity production. Some alternatives to reduce the damage caused by dams are efficient end-use, the use of newer technologies like solar energy, thermal energy, etc.

2. How can we avoid resource mismanagement and over-exploitation?

Ans: Conservation and management of water resources can help to prevent overexploitation and misuse of these resources. Conservation can help to prevent an ecological crisis from arising as a result of its shortage, as well as the damage to our natural ecosystem.

Keeping the following in mind that can help you manage your resources better:

(a) Water pollution prevention, so that accessible water resources are not contaminated.

(b) Water-saving technologies, as well as resource recycling and reuse, should be developed as part of integrated water resource management. The use of rainwater harvesting should be encouraged.

This is all about dams and their functioning. Dams are useful to human beings in different ways but we have to pay a huge price for these benefits. This article explains the alternatives to these humongous constructions.

Did You Know?

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The Three Gorges Dam (China) is the world’s largest dam (181m in height and 2.34 km in length) and the heaviest concrete structure ever built, weighing more than 144 million tons. Its electric station has a capacity of 22,500 megawatts, powered by 32 main generators.

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FAQs on Alternatives to Dams: Innovative Solutions in Biology

1. What are the most viable alternatives to building large dams for water management?

The most viable alternatives to large dams focus on decentralised and sustainable water management techniques. These methods aim to conserve water, recharge groundwater, and reduce the large-scale environmental and social disruption caused by big dams. Key alternatives include:

Watershed Management: This involves restoring forests and vegetation in catchment areas, which naturally slows runoff, increases water percolation, and prevents soil erosion.
Rainwater Harvesting: A traditional method of collecting and storing rainwater from rooftops and open spaces in tanks, ponds, or underground reservoirs for future use.
Groundwater Recharge: Actively replenishing aquifers using structures like percolation tanks, check dams, and injection wells.
Water Conservation and Efficiency: Improving efficiency in agriculture with methods like drip irrigation and recycling water in industrial and domestic settings to reduce overall demand.

2. Why is finding alternatives to large dams important for the environment?

Finding alternatives is crucial because large dams have significant negative environmental impacts. They cause widespread deforestation by submerging vast areas of land, leading to a loss of biodiversity. Dams also obstruct the natural flow of rivers, which disrupts the migration and breeding cycles of aquatic life like fish. Furthermore, the blockage of nutrient-rich sediment flow can degrade downstream ecosystems and deltas, impacting agriculture and fisheries.

3. How do check dams and percolation tanks work as alternatives to large dams?

Check dams and percolation tanks are small-scale structures that serve as effective alternatives by focusing on local water conservation and groundwater recharge. Check dams are small barriers built across streams to slow down water flow, which allows more water to seep into the ground and raises the local water table. Percolation tanks are artificially created surface water bodies that collect rainwater and allow it to percolate slowly into the ground, replenishing groundwater sources for wells and borewells in the vicinity.

4. What are the main disadvantages associated with the construction of large dams?

The construction of large dams presents several significant disadvantages:

Social Problems: They displace a large number of people, including tribal and rural communities, leading to the loss of homes, livelihoods, and cultural heritage without adequate compensation or rehabilitation.
Economic Problems: They require enormous public investment, often with long gestation periods and without proportionate benefits for all sections of society, especially the displaced.
Environmental Problems: They contribute to deforestation, loss of biodiversity, and trigger ecological imbalances. They also pose risks of reservoir-induced seismicity (earthquakes).

5. How does a decentralised water management system compare to a single large dam?

A decentralised water management system, using multiple small-scale methods like rainwater harvesting and check dams, is often considered more resilient and equitable than a single large dam. While a large dam provides centralised control over a massive water volume, its failure can be catastrophic. In contrast, a decentralised system distributes risk and empowers local communities to manage their own water resources. This approach promotes groundwater recharge locally, ensures a more even distribution of water, and has a significantly smaller environmental and social footprint.

6. Can improving agricultural practices reduce the need for constructing new dams?

Yes, significantly. A major reason for building dams is to provide water for irrigation. By adopting water-efficient agricultural practices, the demand for irrigation water can be drastically reduced. Techniques like drip irrigation and sprinkler systems deliver water directly to the plant roots, minimising wastage through evaporation. Additionally, choosing crops that are suitable for the local climate (less water-intensive) and improving soil health to retain more moisture can further decrease the dependency on large-scale irrigation from dams.

7. What are some examples of natural alternatives to dams for flood control?

Natural alternatives to dams for flood control focus on enhancing the landscape's innate ability to absorb and manage excess water. The most effective examples include restoring wetlands and floodplains, which act as natural sponges, soaking up and slowly releasing floodwaters. Reforestation of hillsides and riverbanks helps to increase water absorption and reduce rapid runoff. Additionally, maintaining the natural meanders of a river, rather than straightening it, slows down the water's velocity and reduces downstream flood peaks.