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Cross-Border Floods

The River Wild

From its source in Tibet, the Yarlung Tsangpo River meanders 2,900 kilometers and passes through India and Bangladesh. With devastating annual floods and potentially hazardous hydroelectricity projects in the pipeline, there is an urgent need for improved cross-border co-operation

January 2012 Issue | by Wang Yan

For Chandan Duarah and Mubina Akhtar, a couple in their thirties who live in Assam State, south of the Himalayas in northeast India, the Brahmaputra is like a kind yet quick-tempered mother. Lovingly nurturing her children in the river basin but prone to bouts of rage, the river’s temper shifts with the seasons.

The Indian couple now live in Guwahati, the capital of Assam, which is situated among the hills on the bank of the Brahmaputra. Few cities in the state enjoy such a favorable perch; Guwahati narrowly escapes the annual flooding of the Brahmaputra River during the monsoon season. Residents across most of the state are not so fortunate, and often fall victim.

Due to seismic activity in the fragile geological base of the Himalayan plateau, in addition to a high level of annual precipitation, the northeastern part of India is constantly under threat from flooding.

Suffering

Each year, a few months of hot, dry weather in India give way to the southwest monsoon in early June, followed by three months of strong winds and flooding. During this period the days are long and humid, and the countryside is verdant. Yet during the monsoon, floods “have been occurring annually since 1950, and the tributaries of the Brahmaputra also swell, causing havoc in the region,” Chandan told our reporter.

Locals will never forget the most catastrophic flood in Indian history, which struck in early June 2000 and inundated five districts of the state of Arunachal Pradesh and parts of Assam, killing at least 30, leaving over 100 missing and rendering 50,000 homeless. The flood was triggered by the overflowing of a lake in the upper reaches of the Brahmaputra River, or Yarlung Tsangpo as it is called in China’s Tibetan region, which had formed after a landslide.

Originating from the Chema Yongdong glacier in the Kailas Ranges in southwestern Tibet at an elevation of 5,300 meters above sea level, the Brahmaputra is one of the world’s largest rivers, with a drainage area of 580,000 square kilometers (50.5 percent in China, 33.6 percent in India, 8.1 percent in Bangladesh and 7.8 percent in Bhutan).

On April 9, 2000, a massive landslide occurred along a mountain slope in Bomi County in the Yigong region of Tibet. Three hundred million cubic meters of displaced soil and ice dammed up the Yigong Zangbu River, a large tributary of the Brahmaputra. It created a 90 meter-high, 3,000 meter-long and 1,500 meter-wide dam, 300 kilometers upstream of the Indian border. Dr Yang Yong, 52, a well-known Chinese independent scientist who has traveled down most major river systems inside China and its neighboring countries, said that the Yigong landslide in 2000 was “the largest geological disaster of its kind in the world.”

According to Yang, a team of scientists rushed to the spot immediately after the mudslide. “We estimated that the natural dam could hold a total of 3 to 4 billion cubic meters of water, and urged the Chinese government to work out a plan to release the backed-up water by drilling before the dam collapsed,” Yang recalled. “We also proposed that the government evacuate residents from downstream areas and inform their Indian counterparts about the situation so that people who might be affected could prepare for the approaching disaster.” Tragically, the dam collapsed before the drilling project was completed in early June that year, leading to a massive flood that inundated large areas of India as well as Tibet.

Whether the Chinese side sent the warning to the Indian side in time or not remains a matter of contention. Partha Jyoti Das, head of water, climate and hazard projects at Aaranyak, a conservation NGO from Guwahati, stated that Chinese scientists predicted the flash flood on the basis of the rising of water level in April 2000, yet the Indian authorities ignored the warning. However, various Indian media blamed China for the catastrophic flooding, accusing their neighbor of withholding vital hydrological data concerning the Brahmaputra’s flow through Chinese territory.

Whoever is to blame, one thing is certain: the warning had not been passed on to the Indian residents living along the Brahmaputra before the unstable dam gave way on June 10, 2000. “That day, the river rose by an unprecedented 100-120 feet, and devastated four districts of Arunachal Pradesh,” said Chandan, in whose mind the chilling memory is permanently etched.

Panic

In addition to constant worries over seasonal flooding, people in northeast India now face another, far more avoidable threat: large hydropower projects in the Brahmaputra basin, promoted by the Indian government over the last decade. 

Recent years have seen major conflicts emerge in Assam and Arunachal Pradesh states over the impact of over 100 dams planned in upstream Arunachal. According to the report Damming Northeast India, “repeated incidents of floods caused by upstream projects have been a major catalyst triggering debate over the impact of dams in Assam.” In 2004, at least 22 people were killed by flash floods in Assam caused by the release of water from a 405-megawatt hydroelectricity project in Arunachal Pradesh.

While the Indian government is eyeing the huge unexploited hydroelectric potential of the Brahmaputra, often called “the nation’s future powerhouse,” Chinese players are also beginning to exploit the river’s hydropower potential. Last November, China began damming the river at its Zangmu (Nagmu) section for its first major hydropower station on the river, a 510-megawatt project, scheduled to come into operation in 2014. Another five hydropower plants along the river will follow, with a total capacity of 2,000 megawatts. All of these are supposedly environmentally friendly “run-of-the-river” (ROR) projects, in which electricity is generated directly by river flow, without water storage or flow modification.

Despite India’s own projects to divert water from the Ganges or to build controversial dams on international rivers such as the recent Tipaimukh Dam, which Bangladeshi media claim deeply harm the ecology and economy of Bangladesh, many Indians in turn worry that China plans to divert water from the Brahmaputra to its own drought-prone regions; since the 1990s, both international and Indian media have consistently alleged that China’s construction aims to alter the river’s flow. Understandably, this leaves residents of Assam in a state of fear, and quick to assume the worst at the slightest fluctuation in the river’s flow.

Chandan expressed local concerns over hydropower projects to NewsChina: “The disaster in 2000 could be a small-scale illustration of what could happen if the Brahmaputra project is some day completed. At that time, the breach of a natural dam in Tibet would lead to severe floods and leave many people dead. It is not difficult to understand that areas downstream in Arunachal or Assam are extremely vulnerable to goings-on upstream in Tibet.”

Reassurance

On October 12, Jiao Yong, vice minister of the Chinese Water Resources Ministry, officially stated that China had no plans to divert the Brahmaputra, considering “technical difficulties, environmental impact and relations with the neighboring countries.” The Chinese government’s refusal to acknowledge the possibility of a Brahmaputra diversion came as a relief to both the Indian government and the local population, at least for the time being.

Four days later on October 16, according to the Indian Express, Assam Chief Minister Tarun Gogoi expressed that “This is the first time China has actually said it will not divert the Brahmaputra. Even so, I have requested the Centre [the Indian government] to keep an eye [sic].”

While China has denied that it plans to divert the Brahmaputra, it is mulling over plans to construct another large project on the river. According to Dr Yang Yong, who obtained the project plan from designers of HydroChina Chengdu Engineering Corporation, the enormous project will have a capacity of 49,000 megawatts, twice that of China’s flagship Three Gorges project, and is to be constructed in the “Great Bend” of the river, where the Brahmaputra takes a sharp southward turn toward south Tibet and India.

According to the plan, a portion of the Yarlung Tsangpo water inflow will be diverted, before the Great Bend, into a 20-kilometer tunnel dug through the mountains across the Bend. Then the water flow will run down the tunnel through nine consecutive ROR projects before rejoining the Yarlung Tsangpo’s main stream.

The initial proposal of the Great Bend project came out in 2000, with the basic aim of utilizing the natural momentum of water to generate electricity. “There will be no reservoirs except at the diversion point, where a temporary 50-meter-high dam will be built, and only 50 billion cubic meters of annual water inflow will be diverted at this spot for electricity generation,” Yang added. “Considering the total annual water outflow of 150 billion cubic meters at Pasighat, on the border with India, at most one-third of the water will be rechanneled. Therefore, there will be little effect on the downstream flow of the river.” Yang also explained that the difficulty of construction in the earthquake-prone region posed major challenges, so the proposal was unlikely to be implemented in the next ten years.

Geological Instability

Due to the collision of the Eurasian and Indian tectonic plates, the Brahmaputra Valley and the adjoining mountain ranges are seismically unstable. Earthquakes in 1897 and 1950, both measuring 8.5 on the Richter scale, were among the most severe in recorded history. Glacial lakes become a major hazard if they are ruptured by earthquakes; according to the United Nations Environment Program (UNEP), there have been at least 35 glacier lake outbursts in Nepal, Pakistan, Bhutan and China during the last century.

Himalayan Karakorum Hindukush (HKH) mountain ranges possess the largest glaciers in the world outside of the polar regions. A research paper by Li Zongyi of the Chinese Academy of Sciences recently published in British academic journal Environmental Research Letters indicated that glaciers in southwestern China have encountered consistent warming at a statistically significant level between 1961 and 2008. “In the face of rising temperatures, the fronts of 32 glaciers and the area of 13 glacial basins have retreated, and the mass losses of 10 glaciers have been considerable. As a result, glacial lakes in six regions have expanded and the flow of melt water washing through four basins has also increased. Yet, all this is but a fraction of the retreating glaciers in southwestern China,”according to the paper.

Since 1990, lake overflows have been observed fairly frequently on the Qinghai-Tibet Plateau. According to domestic report, in Naqu, Qinghai Province, over 100 lakes have expanded in area, thus inundating over 100,000 hectares of grassland and forcing the  relocation of over 100,000 people.

Fast growing lakes greatly increases the probability of glacial lake outburst floods (GLOFs) which have been reported in many Himalayan basins. According to a report released in May 2010 by the International Centre for Integrated Mountain Development (ICIMOD) in Kathmandu, “it is estimated that there are over 8,000 glacier lakes in the HKH region with more than 200 of them identified as potentially dangerous.”

Early Warning System

Taking into account the severe threat of melting glaciers and, in turn, potential GLOFs, a sound network of monitoring and early warning systems to allow downstream residents time to take evasive action is urgently needed both domestically and between countries with trans-border river connections. “In most cases, there would be little or no warning, with insufficient time for complete a evacuation,” the UNEP report said.

Efforts towards the establishment of a flood forecasting system got underway in India in November 1958 when the Flood Forecasting Unit was created for the River Yamuna at Delhi. By 2006, a total of 175 regular flood forecasting stations had been set up in India. However, reliable trans-border early warning systems do not yet exist among the Himalayan region countries. Only sporadic meteorological and hydrological data are shared.

“Were there a trans-border early warning system between China and India, people in Assam and Arunachal could be better prepared to save their property, livestock and themselves from flash floods,” said Chandan Duarah.

Further Cooperation

After the 2000 Yigong mudslide, a Memorandum of Understanding to share data on water level, discharge and rainfall was signed in 2002 between China and India. Since then, data provided by the Yanghen, Nugesha and Nuxia stations on the Brahmaputra River inside China have been transmitted to corresponding Indian agencies twice a day. The data provided by China have helped in flood forecasting, and have kept the Indian Water Ministry updated with what is happening on the upper reaches of the Brahmaputra. In accordance with the Memorandum of Understanding, any plans to divert the Brahmaputra will have to be made known to the Indian Water Ministry beforehand.

“China’s own research in the Himalayan region didn’t get started until the late 1950s, and so far fixed-position monitoring of water resources, covering the meteorological, hydrological and glacier aspects, are still relatively insufficient,” said Professor Kang Shichang, assistant director of the Institute of Tibetan Plateau Research at the Chinese Academy of Sciences (CAS) in an interview with NewsChina.

Some forms of international cooperation in water-resource research projects in this region are in their fledgling stages. The CAS launched a Third Pole Environment (TPE) project a couple of years ago, under which Chinese scientists and their counterparts from Nepal, India and Pakistan meet on a regular basis to exchange information, technology and scientific perspectives. According to Dr Kang, China has also started some research cooperation projects with the EU.

“All these projects combine to mark a good start. Yet more efforts are needed for more profound cooperation and wider sharing of information,” Kang told the reporter.

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