Water level lowered by 86cm (Bhutan)


Glaciologist Karma Toeb, leader of the team to Thorthormi, said that initial target for this year – from July to September - was to reduce the water level of Thorthormi by 1.67 m. “But the Cyclone Aila in May hampered the mitigation work and the target was brought down to one metre,” he said.

“We could have brought down the water level to more than one metre had we worked for three months as planned. But the actual excavation work went on only for two months,” said Karma Toeb.

The team, comprising 309 people from lower altitudes and villagers from Laya and Lunana, including about 20 women, had to walk for more than an hour from the camp to reach the site. There were 12 officials from the department of roads, park, health, Gasa dzongkhag and royal Bhutan army. Most of the workers were high school dropouts. These workers are paid Nu 15,000 a month and provided insurance of Nu 108,000 for each one of them.

The project began with site development till the first week of September, clearing the boulders. The team had to drain water from the lake by digging a path towards two subsidiary lakes of the Thorthormi, which feed the Punakha Phochu. The operation was to prevent water from flowing down to Rapstreng, which is on the other side and at a lower position, 74 m below Thorthormi.

Bad weather was the major setback, apart from other difficulties, said Karma Toeb. “Daily rainfall hampered the work,” he said.

Thorthormi lake is ranked as one of the most dangerous in Bhutan, with a size of 3.42 sq km, thrice the dimension of Lake Lugge that burst in 1994. The massive ice surrounding Lake Thorthormi is found to be melting fast at 30-35 m a year, filling up the lake quickly.

Geologists say that the natural dam walls between the lakes Thorthormi and Rapstreng is only 32.5 m thick at the crest and is getting thinner every year. If the wall separating the lakes gave way, Thorthormi, being on higher ground, would flow into Raptstreng and cause about 53m cu m of water to rush down the valleys of Punakha, Wangduephodrang, Tsirang and Dagana.

The project, spread over three years, is worth Nu 130 million and funded by global environment facility (GEF). The target is to reduce the Thorthormi’s water level by 5m within three years to avoid its combination with lake Rapstreng and prevent glacial lake outburst flood.

Meanwhile, despite the harsh weather, workers said that working in Lunana was an unforgettable experience. Tenzin Dorji, 25, from Paro, a class 10 dropout said that it was a good experience. “Walking for more than one hour every day back and forth from the site was really tiring and, that apart, it was a learning experience,” he said, adding the amount he was paid was satisfactory.

The team will work on the lake for three to four months every year till 2012.