Tag Archives: dams and floods

Robots to the Rescue: Best Dams on Amazon River

Leave a reply

Proposed hydropower dams at more than 350 sites throughout the Amazon require strategic evaluation of trade-offs between the production electricity and the protection of biodiversity. 

Researchers are using artificial intelligence (AI) to identify sites that simultaneously minimize impacts on river flow, river connectivity, sediment transport, fish diversity, and greenhouse gas emissions while achieving energy production goals. The researchers found that uncoordinated, dam-by-dam hydropower expansion has resulted in forgone environmental benefits from the river. Minimizing further damage from hydropower development requires considering diverse environmental impacts across the entire basin, as well as cooperation among Amazonian nations. 

Alexander Flecker et al., Reducing adverse impacts of Amazon hydropower expansion, Science, Feb. 17, 2022

Water Conflicts: Who Owns the Nile River

Leave a reply

The Grand Ethiopian Renaissance Dam is a giant edifice that would span the Blue Nile, the main tributary of the Nile river.  Half a century in the making, the hydro-electric dam is Africa’s largest, with a reservoir able to hold 74bn cubic metres of water, more than the volume of the entire Blue Nile. Once filled it should produce 6,000 megawatts of electricity, double Ethiopia’s current power supply. Millions of people could be connected to the grid for the first time. More than an engineering project, it is a source of national pride.

For Egypt, however, it seems a source of national danger. Over 90% of the country’s 100m people live along the Nile or in its vast delta. The river, long seen as an Egyptian birthright, supplies most of their water. They fear the dam will choke it off. Pro-regime pundits, not known for their subtlety, have urged the army to blow it up….Ethiopia wants to start filling the reservoir during this summer’s rainy season. On June 26th, 2020 after another round of talks, Egypt, Ethiopia and Sudan pledged to reach a deal within two weeks. Ethiopia agreed not to start filling the dam during that period.

Diplomats say most of the issues are resolved. But the outstanding one is big: how to handle a drought. Egypt wants Ethiopia to promise to release certain amounts of water to top up the Nile. But Ethiopia is loth to “owe” water to downstream countries or to drain the reservoir so much that electric output suffers. It wants a broader deal between all riparian states, including those on the White Nile, which flows out of Lake Victoria down through Uganda and Sudan.

Even if talks fail and Ethiopia starts filling without a deal, Egyptians will not find their taps dry. There is enough water in the reservoir behind Egypt’s Aswan High Dam to make up for any shortfall this year. But the mood in both countries is toxic. Egyptians have cast Ethiopia as a thief bent on drying up their country. In Ethiopia, meanwhile, Egypt is portrayed as a neocolonial power trampling on national sovereignty. The outcome of the talks will have political consequences in both countries, and perhaps push them to the brink of conflict—at a time when Egypt is already contemplating involvement in a war in Libya.

Ethiopia’s grand dam became a reality and a national obsession under Meles Zenawi, the longtime prime minister who ruled until 2012. His political masterstroke was asking Ethiopians to finance it through donations and the purchase of low-denomination bonds…. Most contributed voluntarily, but there was always an element of coercion. Civil servants had to donate a month’s salary at the start. Local banks and other businesses were expected to buy bonds worth millions of birr. ….

Excerpts from The Grand Ethiopian Renaissance Dam: Showdown on the Nile, Economist, July 4, 2020

.

Choking the Water: Dams, Dams and More Dams

Leave a reply

Since Tibet is part of China, Chinese engineers have been making the most of that potential. They have built big dams not only on rivers like the Yellow and the Yangzi, which flow across China to the Pacific, but also on others, like the Brahmaputra and the Mekong, which pass through several more countries on their way to the sea.

China has every right to do so. Countries lucky enough to control the sources of big rivers often make use of the water for hydropower or irrigation before it sloshes away across a border. But If the countries nearest the source of water, like China,  suck up too much of the flow, or even simply stop silt flowing down or fish swimming up by building dams, the consequences in the lower reaches of the river can be grim: parched crops, collapsed fisheries, salty farmland.

Tension and recrimination have been the order of the day for China and its neighbours… In part, this is because a river like the Mekong does not contain enough water to go round. China has already built 11 dams across the main river (never mind its tributaries) and has plans for eight more; the downstream states have built two and are contemplating seven more. Last year, during a drought, the river ran so low that Cambodia had to turn off a big hydropower plant. Even when rainfall is normal, the altered flow and diminished siltation are causing saltwater to intrude into the Mekong delta, which is the breadbasket of Vietnam, and depleting the fish stocks that provide the only protein for millions of poor Cambodians.

China has long resisted any formal commitment to curb its construction of dams or to guarantee downstream countries a minimum allocation of water. It will not even join the Mekong River Commission, a body intended to help riparian countries resolve water-sharing disputes…

China has not signed any agreements about managing the Mekong with the other countries it flows through, so is not obliged to share a particular amount of water with them, nor even provide data on the flow or any warning about the operations of its dams. It does provide the Mekong River Commission with a trickle of information about water levels and planned releases from dams, which helps with flood-control lower down the river

Excerps from Water Torture: Hydropower in Asia, Economist, May 16, 2020; Torrent to Tickle: the Mekong, Economist, May 16, 2020

Dams on Nile River

Leave a reply

Since Ethiopia announced its plan to build the Grand Ethiopian Renaissance Dam, it has inspired threats of sabotage from Egypt, which sits downstream and relies on the Nile for electricity, farming and drinking water. Egypt claims that it is entitled to a certain proportion of the Nile’s water based on colonial-era treaties….

By 2050 around a billion people will live in the countries through which the Nile and its tributaries flow. That alone will put enormous stress on the water supply. But according to a study by Mohamed Siam and Elfatih Eltahir of MIT, potential changes to the river’s flow, resulting from climate change, may add to the strain. Messrs Siam and Eltahir conclude that on current trends the annual flow could increase, on average, by up to 15%. That may seem like a good thing, but it could also grow more variable, by 50%. In other words, there would be more (and worse) floods and droughts.

There is, of course, uncertainty in the projections, not least because differing global climate models give different numbers. But the idea that the flow of the Nile is likely to become more variable is lent credibility, the authors argue, by the fact that trends over decades seem to agree with them, and by consideration of the effects of El Niños. 

More storage capacity will be needed to smooth out the Nile’s flow. But unlike Egypt’s large Aswan Dam, which was built with storage in mind, the new Ethiopian one is designed for electricity production. Once water starts gushing through its turbines, it is expected to produce over 6,000 megawatts of power. It is unclear, though, if the structure has the necessary flexibility to meet downstream demands in periods of prolonged drought.

The talks between the three countries, Ethiopia, Sudan and Egypt, seem to be glossing over the potential effects of climate change. “Nowhere in the world are two such large dams on the same river operated without close co-ordination,” says another study from MIT. But so far co-operation is in short supply. The latest round of talks has been postponed. Even the methodology of impact studies is cause for wrangling.

Excerpts from: Climate Change and the Nile: Flood and Famine, Economist, Aug. 5, 2017

Dams and Drought: the Amazon

Leave a reply

The São Luiz do Tapajós (SLT) project… would dam one of the last big unobstructed tributaries of the Amazon. The project would provide about a third of the hydropower that Brazil plans for the forthcoming decade, but it would also flood 376 square km (145 square miles) of land where the Munduruku hunt, fish and farm. “The Tapajós valley is our supermarket, our church, our office, our school, our home, our life,” explained Mr Kabá.

The tussle over the Tapajós dam is part of a bigger fight about Brazil’s energy future. SLT is an example of a new sort of hydropower project, which floods a smaller area than traditional dams and therefore ought to cause less disruption and environmental damage. The massive Itaipu dam on the border with Paraguay inundated an area nearly four times as large. But critics of hydropower say “run of river” projects like SLT, which use a river’s natural flow to turn turbines, do not work as well as advertised. Though less destructive than conventional dams, which require bigger reservoirs, they still provoke opposition from people like the Munduruku. Other energy sources, such as gas and wind, are becoming more competitive. Brazil has “an opportunity” to rethink its energy policies, says Paulo Pedrosa, an energy official.

Hydropower has long been Brazil’s main way of generating electricity. Most forecasts suggest it will remain so. The government intends to build more than 30 dams in the Amazon over the next three decades. 

Climate change may worsen the problem. Some climate models predict that river flows in large parts of the Amazon will fall by 30% in coming decades. Deforestation is delaying the onset of the rainy season in some areas by six days a decade, according to research published in Global Change Biology, a journal.   Drought can be expensive. In 2014 power from conventional dams dipped because of a dry spell, forcing electricity companies to buy from gas- and coal-powered generators at high spot prices. The risk of such fluctuations rises with run-of-river dams. Carlos Nobre, a former chief of research at the ministry of science, technology and innovation, thinks more frequent droughts will make future hydropower projects in the Amazon unprofitable.

Brazil’s potential for solar and wind energy is among the highest in the world. The government has promoted them with lavish tax breaks. In the blustery north-east, wind power overtook hydropower this year; wind turbines now generate 36% of the region’s electricity, up from 22% in 2015. The Energy Research Company, a firm linked to the energy ministry, expects renewable generating capacity apart from hydropower to double by 2024.

Generators fuelled by natural gas have been hurt by the subsidies lavished on renewable energy. But, though less climate-friendly than hydropower, they are beginning to compete with it as a source of steady baseload electricity. Brazil now produces gas in abundance as a by-product of pumping oil from its offshore wells. Its marginal cost of production is nearly zero. The future of baseload energy is “hydro-thermal”, rather than hydro alone, says Adriano Pires of the Brazilian Infrastructure Centre, a think-tank in Rio de Janeiro.

Excerpts from Dams in the Amazon: Not in my valley, Economist,  Nov. 5, 2016

The Most Dangerous Dam

Leave a reply

Sensors installed by American army engineers in December 2015 show widening fissures in the fragile gypsum base underneath the Mosul dam,  though no one can predict when a breach might occur….The Iraqi government has now contracted with the Trevi Group, an Italian firm, which it hopes will offer a more advanced and permanent method of plugging cavities in the stone base than the constant maintenance it has required for the past 30 years. That maintenance came to an abrupt halt after IS seized the dam in August 2014, and has continued only intermittently after it was seized back three weeks later. Essential equipment went missing then, and half its staff decided not to return to work.

One study says that if the dam collapses, Mosul would be submerged within hours. Another warns that half a million Iraqis could be killed by floodwaters, and more than a million forced from their homes. Disease and looting as the floodwaters raced through Baiji, Tikrit, Samarra and even parts of Baghdad would complete that dreadful scenario.

The dam was built by an Italian-German consortium and started operating in 1986. Because of the high proportion of gypsum in the area, the construction included a grouting tunnel to allow almost constant injection of cement and drilling mud into crevices in the base that are widened by the water flowing through them. America’s Army Corps of Engineers warned in 2005 that the “extraordinary engineering measures” needed to maintain its structural integrity made the structure potentially the most dangerous in the world.*** But taking the dam out of commission is not an attractive option. Emptying the reservoir would leave Iraqis seriously short of drinking and unpolluted irrigation water in the summer.

Excerpts from The Mosul dam: A watery time-bomb, Economist, Feb. 13, 2016, at 42

***  The dam was constructed on a foundation of water soluble gypsum!!! More than 50,000 tonnes  of material have been injected into the dam since leaks began forming shortly after the reservoir was filled in 1986, and 24 machines currently continuously pump grout into the dam base. Between 1992 and 1998 four sinkholes formed downstream of the dam and a fifth sinkhole developed east of the dam in February 2003 which was filled several times. In August 2005 another sinkhole developed to the east (Wikipedia).

Costs of Dams: Vietnam

Leave a reply

Hydropower has boomed in Vietnam over the past decade and now generates more than a third of the country’s electricity. In 2013 the National Assembly reported that 268 hydropower projects were up and running, with a further 205 projects expected to be generating by 2017. They are helping to meet a national demand for energy that the authorities forecast will treble between 2010 and 2020. Other power sources are less promising, at least in the short run. A plan to build several nuclear reactors by 2030 is behind schedule, for example. And Vietnam’s coal reserves, mostly in the north, are not easy to get at.

Yet the hydropower boom comes at a price. Rivers and old-growth forests have been ravaged, and tens of thousands of villagers, often from ethnic minorities, displaced. Many have been resettled on poor ground. Those who have stayed are at risk of flash floods caused by faulty dam technology and inadequate oversight. Green Innovation and Development Centre, an environmental group in the capital, Hanoi, says shoddy dam construction is the norm, and developers ignore the question of whether their projects could trigger earthquakes…

Many hydro-electric companies are owned by or affiliated with Electricity Vietnam (EVN), the loss-making state power monopoly. Because hydropower is Vietnam’s cheapest source of electricity, EVN resists investing in measures such as dam-safety assessments that would further erode its financial position. As it is, even though environmental-impact assessments for hydropower projects are required, they are never published, according to the United Nations Development Programme….. Hydropower companies want to keep their mountain reservoirs as full as possible in order to generate as much electricity as Vietnam’s rivers allow. But that narrow focus can deprive farmers of irrigation in the dry season. And when heavy rains come in the summer and autumn, floodwaters cascade over the dam walls with little or no warning.

Hydropower in Vietnam: Full to bursting, Economist, Jan.10, 2015, at 35