The Tipaimukh Dam Debate

Posted by: Sabrina on: July 31, 2009

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I found a highly informative article that analyses the Tipaimukh debate in simple language. Excerpts:

Bangladesh already has a complex and increasingly difficult relationship with water. River erosion, rising sea levels, increased salinity and arsenic in ground water pose formidable problems. Rivers in the North and Southwest have dried up, and saline water has advanced from the Bay of Bengal. Critics blame the Farakka barrage that India put into operation in 1975 for drying up large parts of the country, affecting navigation and adversely influencing the environment, agriculture and fisheries. Water resources experts also say India’s dam on the Teesta river has affected the performance of Bangladesh’s own irrigation barrage, seriously hurting millions of farmers in the country’s north. 

Faced with such intractable problems, Bangladesh can ill afford another monstrosity that will squeeze the rivers’ life-giving flow. “What is power-luxury for India is a life-and-death question for Bangladesh,” said Prof Muzaffer Ahmad, president of Bangladesh Paribesh Andolon (Bapa), an environmental forum. “Energy cannot be more important than human disaster.”

 The passionate opposition to the Tipaimukh dam has so far focused on the possibility of desertification and increased salinity. It is easy to draw comparisons with Farakka. But the freewheeling debate about desertification may be hurting, not helping, Bangladesh’s cause. 

Indian diplomats have been quick to point out the differences between Farakka and Tipaimukh. “The so-called experts in Bangladesh are using scare tactics,” said the Indian High Commissioner to Bangladesh Pinak Ranjan Chakravarty in an aggressive tone that surprised many in the diplomatic circles. “This is a hydroelectric dam. In order to generate power, it must release water. So, Bangladesh will probably get more water in the dry season.” 

The haors or flood plains of the Surma basin are unique ecosystems home to a rich variety of flora and fauna. Parts of the region have been designated Ramsar sites of international importance, and protected by the Bangladesh government as Ecologically Critical Areas (ECA). The total area of this wetland covers nearly 25000 square kilometers and supports approximately 20 million people. 

The wetlands of the Surma basin perform two crucial functions: they serve as the granaries and fisheries of the Northeast. Many of the species inhabiting the haors will be threatened by loss of habitat, but more importantly it is the people of the wetlands who might be on the endangered list if the Tipaimukh dam goes ahead.

 The rivers are woven tightly into the lives of the haor people. They literally live by the ebb and flow of the waters. Any artificial alteration of the “flood pulse” could affect food security and bring disaster to the region.

 “If the water increased in the Surma and Kushiara during the dry season, the haor would be waterlogged. We would not be able to plant,” says Rustam Ali “there would be no harvest.”

 Studies of large hydroelectric dams worldwide have shown the artificial flattening of the “flood pulse” adversely affects lower riparian fishing and agricultural communities. A study carried out by the Helsinki University of Technology on the Mekong River found that hydroelectric dams in China drastically reduced the load of fertile sediment carried by the monsoon floods, affecting the fertility of the Mekong’s fisheries in Thailand, Laos and Cambodia.

 

Some experts suggest that the Tipaimukh dam may help control flash floods, but others have warned of worse flooding to come. “The dam and the reservoir have certain limitations,” says Dr Jahir Bin Alam, head of the Department of Civil and Environmental Engineering at Shahjalal University of Science & Technology. “The dam may control some of the annual flooding. But when there is a really big rise in water levels, the gates will have to be opened to save the dam itself. That will lead to a much bigger flood downstream.”

 

There are other aspects of large hydroelectric dams that are well documented but much less well known. The major hydrological impact of such dams is to impose on the river an unnatural pattern of flow variations. As the environmentalist Wallace Stegner puts it, “a dammed river is not only stoppered like a bathtub, but it is turned on and off like a tap.”

 

In 2000, the World Commission on Dams found that the “changed hydrological regime of rivers has adversely affected floodplain agriculture, fisheries, pasture and forests that constituted the organising element of community livelihood and culture.” 

A dam holds back sediments and nutrients that would naturally replenish downstream ecosystems. Deprived of its sediment load, the “hungry” river seeks to recapture it by eroding the downstream river bed and banks, undermining bridges and other riverbank structures. Riverbeds downstream of dams are typically eroded by several meters within the first decade of commissioning of the dam. International hydrologists say the damage can extend for hundreds of kilometres below a dam.

 

Even more alarming is the finding that riverbed deepening will also lower groundwater tables along the course of a river, threatening vegetation and local wells in the floodplain and requiring crop irrigation in places where there was previously no need. With ground water tables already seriously low in Bangladesh, further lowering would precipitate a crisis in urban areas hugging the rivers, such as Sylhet, Maulvibazar and Habigonj. 

The Indian High Commissioner Pinak Ranjan Chakravarty has rubbished claims that the Dam would be harmful for Bangladesh. He dismissed worries that the reservoir may cause seismic disturbance in quake-prone Manipur, saying, “There is absolutely no evidence that dams cause earthquakes.” But the High Commissioner may be on shaky ground. 

Worldwide, there is a growing body of evidence that shows earthquakes can be induced by very large hydropower dams. The most serious case may be the Richter 7.9 magnitude Sichuan earthquake in May 2008, which killed an estimated 80,000 people and has been linked to the construction of the Zipingpu Dam. In a paper prepared for the World Commission on Dams, Indian scientist Dr. V. P Jauhari described this phenomenon, known as Reservoir-Induced Seismicity (RIS). “There is a positive correlation between the height of the water column in the reservoirs and the seismicity induced,” wrote Dr. Jauhari. 

Dr Soibam Ibotombi of the Department of Earth Sciences, Manipur University warns: “The likelihood that during 1991-2015 the (Tipaimukh) region would experience an earthquake of magnitude 7.6 is between 40 and 60 per cent.” Based on a dam-break study conducted as part of Bangladesh’s Flood Action Plan 6 (FAP-6), international hydraulic and environmental experts concluded that in the event of a dam failure at Tipaimukh, a wall of water more than 15 feet high would reach Sylhet within 24 hours. 

“If you put a 50-storey building right in the middle of a living river, no matter how many windows there are do you want to tell me there will be no damage to the ecosystem?” asks Engineer Hilaluddin of Angikar. 

Many experts have also been critical of the decision to send a parliamentary delegation to visit the site. “The dam has not been built, so there is nothing to see but the hills, the river and the sky,” says Ramananda Wangkheirakpam, an environmentalist in Manipur. “The Indian government needs to show it is not breaking international conventions in order to attract foreign investors. We are afraid this visit will legitimise the Dam.” 

The article “The Dam Debate” by Syed Zain Al-Mahmood was published in the Star Magazine. You can read the whole article at http://www.thedailystar.net/magazine/2009/07/02/cover.htm