Hydroelectric power for Climate resilience – Overview of the Victoria Hydropower plant

Through this article, you will get to know the following:

• Past, Present and the Future of the Victoria Dam
• The truth about reservoir induced Earthquakes in Victoria
• Climate change risk on the Victoria power plant
• Environmental impacts of hydroelectric power in Sri Lanka
• The best way forward for Hydro-electricity in Sri Lanka

Background

Fueled by water, hydropower is a clean energy source that has been in use worldwide for many years, and its capacity has steadily increased towards the latter part of the last century. However, while many consider hydropower a renewable energy source, as it relies on the water cycle, others are reluctant to classify hydropower projects under renewables, pointing out that these projects significantly impact fisheries, water flows and the overall environment.

Currently, there are 21 hydroelectric power stations and around 100 mini hydropower projects in Sri Lanka. Hydropower is a key energy source used for electricity generation in the tiny island nation of Sri Lanka, which provided almost all the electricity needs until the early 1990s. A large share of the hydro potential has already been developed, delivering valuable low-cost electricity to many parts of the country.

Currently, hydropower stations are operated to supply both peaking and base electricity generation requirements. However, a substantial number of small hydropower plants which perform under the Standardized Power Purchase Agreement (SPPA) and more are expected to join the fleet during the next few years.

The basic principle of hydropower is using water to drive turbines. Hydropower plants have two basic configurations, either with or without dams and reservoirs. Hydropower dams with large reservoirs can store water over short or long periods to meet peak demand. The facilities can also be divided into smaller dams for different purposes, such as night or day use, seasonal storage, or pumped-storage reversible plants for pumping and electricity generation.

The CFC Sri Lanka team visited the Victoria Power Plant, the tallest Dam in Sri Lanka, which supports a  210 MW power station, the largest hydroelectric power station in the country. We interviewed Mr Udith Ekanayake, a civil engineer at Mahaweli Authority of Sri Lanka, about the possible environmental impacts of this massive Dam.

Past, Present and the Future of the Victoria Dam

The Victoria Dam is located below the Polgolla Diversion barrage and above the Victoria rapids on the mainstream of Mahaweli Ganga (river), just below the point where Hulu Ganga enters the Mahaweli. The Dam’s construction was taken up in 1980 and completed in 1984. 

Eng. Udith Ekanayake explained the reasons for selecting a double curvature arch dam across the river, such as the quantity of water to be stored and the climatic conditions that prevailed at the time. The Victoria Dam was constructed under the Accelerated Mahaweli Development Programme (AMDP). The project had been in planning for 30 years but was accelerated in 1977 to address economic difficulties within the country. The plan is designed to irrigate 365,000 ha (901,935 acres) of land and provide 600 MW of electricity.

The Victoria Dam was initially proposed in 1964 after studies were completed by a Canadian team at Huntings Technical Services and a team from the United Nations Development Program—Food and Agriculture Organization (UNDP-FAO). Construction of the Dam was inaugurated on 14 August 1978 by then President J.R Jayewardene, with the implementation of the main structures beginning in 1980.

The story behind the British grant for the project and claims of zero iron/steel being used to construct the Dam are some of the recurring misinformation on social media streams related to the Victoria Project. Find out how the Factcrescendo Sri Lanka team debunked these myths in this Sinhala language fact check.

Eng. Udith also elaborated on the dimensions of the Dam and its capacity. Accordingly, the Dam measures 122 m (400 ft) tall, with a crest length of 520 m (1,706 ft), a crest width of 6 m (20 ft), and a base width of 25 m (82 ft). The Dam creates the Victoria Reservoir, which has a surface area of 22.7 km² (8.8 sq mi), a gross storage capacity of 722,000,000 m³ and a catchment area of 1,869 km².

Water from the Dam is fed to the powerhouse via a long tunnel, which houses three penstocks. These penstocks created a net head of 190 m (623 ft), feeding three 70 MW turbines capable of generating up to 780 GWh of electrical energy annually.

The Dam consists of eight spillways, each with a width and height of 12.5 m (41 ft) and 6.5 m (21.3 ft), automatically opening when water levels are high. The Dam’s gates, which need power only to close, won an award for “Innovative Design in Civil Engineering” from the Institution of Civil Engineers. The total effective width of the spillways is 100 m (328 ft), allowing a maximum discharge of 8,200 m3/s. In addition, two additional low-level sluices at the Dam’s base will purge accumulated silts behind the Dam.

The Ceylon Electricity Board (CEB) proposed the expansion of the Victoria Hydro Power station by adding an extra tunnel for power generation in 2009, according to Eng. Udith. He said that the future of this project is uncertain as no feedback was received after the completion of the Feasibility study.

The truth about reservoir induced Earthquakes in Victoria

An anomalous seismic sequence of five small (MW < 3) felt earthquakes occurred between 29 August 2020 and 05 December 2020 around the Victoria Reservoir, casting serious doubts over the stability of the Dam. Eng. Udith stated that after analysing the threats posed by the earthquakes on the Dam, it was concluded that there was no risk of collapse.

Following the incident, the Geological Survey and Mines Bureau removed all limestone quarries within 100 meters of Victoria Reservoir overflow. In addition, it suspended the licenses for three large-scale limestone quarries within 100 meters of Victoria Reservoir.

This action was prompted by the tremors experienced in the areas close to the Victoria Reservoir, which has been confirmed to have originated from a limestone quarry in the area. Eng. Udith stated that the restriction had been lifted, and quarries are now operating as usual.

Additionally, Digana and Theldeniya, the areas submerged by the reservoir, are famous locations for calcite and dolomite mineralisation. You can read more about this here, Archived. Hence, the base rock beneath the pool is rich in limestone. Eng. Udith mentioned that the presence of limestone in the area might be the cause of the earthquakes experienced, and researchers are still investigating the matter. Hence we cannot yet confirm the reason for the tremors.

Victoria reservoir puts the Dumbara Valley underwater.

In the case of any development project, a certain number of people will be displaced, relocated and compensated. For example, the Victoria dam project resettled about 30,000 people, four times the estimate. According to Eng. Udith, the primary purpose of the Mahaweli Development was to provide irrigation to practice agriculture within the country’s dry zone. He said that the people were compensated for the loss and relocated into areas with a livelihood of irrigated agriculture.

A considerable amount of land was lost in the Dumbara valley area, which contained fertile land beaming with agriculture. The Lanka Guardian Magazine, published in 1980, carried an article titled “Victoria Project – Development without destruction.” in which Dr L.W Mediwake states, “Few people in this country realise the magnitude of damage this project would do to existing agricultural, industrial and human activity in the Dumbara valley.” He also mentions, “What grows in the moderate climate of Dumabara cannot be grown in the hot, dry zone with different types of climate and soil structure.” An expert from the Lanka Guardian Magazine from 1980 can be reached here.

From early civilisation, it was evident that river valleys were the most fertile lands where people generated their livelihoods. Hence, removing this land to provide irrigation for an unfertile land for the same purpose might seem impractical if not for renewable energy generation.

Climate change risk on the Victoria power plant

Sri Lanka is a country that is highly vulnerable to extreme climatic events. This is because the climate in the central highlands, the area under discussion, varies significantly from the lowland peneplain. The main climate drivers of this region are monsoonal rains that create comparatively drier and wetter conditions and temperature lapse rates along contour lines. 

Eng. Udith mentioned that climate is a primary factor when selecting the location and the shape of dams. Accordingly, the double arch design was chosen for Victoria. However, he added that the climate has drastically changed over the last few decades.

Will climate change pose risks to the Victoria dam? He stated that currently, due to the increase in temperature, the water levels have drastically gone down; hence the Dam is not under threat, yet there is a possibility for anomalous rainfall patterns in the future, which might be risky.

Find the Climate Change risk profile for the Mountain Region in Sri Lanka here for more information.

Environmental impacts of hydroelectric power in Sri Lanka

Hydroelectric power in the form of massive dams has been controversial since its inception due to the environmental impacts it holds. In 1984 the Ecologist magazine was on “dam destruction – the case against super dams.”

The article “The Damnation of Paradise” by L Alexis highlights the harm to be followed in Sri Lanka due to hydropower dams. Accordingly,

• Due to clearing and timber and fuel wood needs, a substantial portion of the forest will be removed.
• A Large number of animals and plants will be destroyed.
• The habitat of most wildlife species in the project area will be severely reduced, thus further jeopardizing the future of endangered species;
• High-quality wildlife habitats comprising 5,600 hectares in the Somawathie Sanctuary and about 15,000 hectares in the northern part of the ‘System C resettlement area will be eliminated;
• About 6,400 hectares of additional high-quality wildlife habitat will be lost in the Mahaweli Ganga floodplain. Breeding and feeding grounds for some fish species, waterfowl and migratory birds will be lost. Livestock grazing areas will also be reduced;
• The water table will rise considerably, necessitating the provision of drainage channels;
• Return flows will lead to a deterioration in water quality downstream;
• Pesticide usage will be increased with subsequent biomagnification throughout the food chain;
• Organic production and energy cycles in estuarine systems will be altered, with a detrimental effect on aquatic life;

Research has shown that many of these predictions have come true and immediate action is required to reverse these impacts.

The Moragahakanda Dam is a more recent example from Sri Lanka, which proves that many of the above concerns have come true by displacing the largest gathering of Asian elephants in Minneriya.

Read more on this in our article on how the impacts of climate change have aggravated the Human Elephant Conflict(HEC) in Sri Lanka.

Another concern is the Eutrophication or algal bloom currently prevalent in the Victoria reservoir due to pesticide use in the surrounding catchments. Additionally, the water stagnates when Victoria is filled, creating an additional risk of Eutrophication. Read more about the Environmental Impacts of the Accelerated Mahaweli Development Program here, Archived.

The CFC team interviewed a few community members affected by the Victoria reservoir. They mentioned that as the water fills up, there has been an increase in diseases, plastic waste collects along the banks, and that invasive plants take over as the water subsides.

There are many case studies that show of Hydropower plant around the world that prove that the costs are higher than the benefits that we get on the cost benefit analysis of the environmental impact assessments. additionally Hydropower project results in many detrimental environmental i impacts including flash flooding, loss of livelihoods, which add to people’s vulnerability. Moreover, Landscape degradation in downstream flood plains of dams may create situations that may lead to increased GHG emissions or reduces carbon sequestration. Many of the visitors had complained of bad smells released, at new hydropower dams which accounts to the vegetation dying and the methane gas released as a result. which proves to show that hydropower dams are indeed not a sustainable source of energy rather it caters to global warming.

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Hydropower vs fossil fuels

In the fight between non-renewables and renewables, there is no argument that hydropower is a better energy source. If hydropower is also considered as a renewable energy source, Sri Lanka currently produces around 70% of its energy requirements from renewable sources. Hydropower contributes almost 20 GWh to the grid. You can find out the daily electricity generation using the CEB website. More benefits of hydropower can be read here.

Modern hydro turbines can convert as much as 90% of the available energy into electricity. On the other hand, the best fossil fuel plants are only about 50% efficient. Hence it is essential to develop hydropower and different renewable energies in a country like Sri Lanka after careful planning and thorough study of the environmental impact and the social and economic aspects of such projects.  

The best way forward for Hydro-electricity in Sri Lanka

Hydropower without dams and reservoirs means producing at a smaller scale, typically from a facility designed to operate in a river without interfering with its flow. They are also called “run-of-the-river” projects. Many consider small-scale hydro a more environmentally-friendly option. Hence, small-scale micro-hydropower projects can significantly and positively impact communities in remote locations.

Sri Lanka has rich watersheds and streams running, especially in the mountain regions; hence it is unnecessary to block main rivers for electricity generation. Although most of the harm is already done, it is vital to create awareness and educate the public on these matters to avoid similar dilemmas in the future.