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Early warning technology protects Nepali villagers from sudden floods

Source: Thomson Reuters Foundation - Wed, 22 May 2013 10:45 GMT
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The Phulping bridge crosses the Bhote Koshi River in Jhirpu Phulpingkatti, a village near Nepal’s border with China. It replaced an old stone bridge, remnants of which can be seen to the left, which was washed away in the floods of 1981. THOMSON REUTERS FOUNDATION/Saleem Shaikh

JHIRPU PHULPINGKATTI, Nepal (Thomson Reuters Foundation) – For years, Deepa Newar and her neighbours lived with the fear that their livelihoods – and even their lives – might be swept away without warning.

Newar and her fellow residents of Jhirpu Phulpingkatti, a village some 112 km (70 miles) northeast of Kathmandu, Nepal’s capital, live perched on the bank of the Bhote Koshi River. The river is prone to sudden, devastating floods that can swamp fields, carry away livestock and even kill those who do not manage to flee to higher ground.

The 2.5 acres (1 hectare) of land on which Newar cultivates paddy rice and maize have suffered severe flooding four times in the last 32 years, most recently in 2011.

Looking at the swirling grey waters of the river that flows into Nepal across the border with China’s Tibet Autonomous Region, 10 km (6 miles) upstream, the 39-year-old recalls those disasters.

“(The river) left behind a trail of death and destruction whenever it has turned into a monster,” she says.

But Newar now enjoys a sense of safety for herself and her family, thanks to an early warning system for floods installed by the Bhote Koshi Power Company (BKPC) at its hydropower plant on the river.

GLACIAL LAKE THREAT

Flash floods can be caused by severe storms or the failure of levees, but the Bhote Khosi River is also susceptible to glacial lake outburst floods. These result from the catastrophic failure of a natural dam high in the mountains that contains glacial meltwater. Such failures are becoming a greater risk as warming temperatures linked to climate change lead to faster glacial melt and greater volumes of water in the lakes.

The Bhote Khosi river basin covers an area of about 3,400 square km (1,300 square miles) and has an estimated 150 glaciers. Of its 139 glacial lakes, whose area totals some 16 square km (6 square miles), 59 are highly vulnerable to outbursts, according to a study conducted by the International Centre for Integrated Mountain Development (ICIMOD), an intergovernmental body of eight countries in the Hindu Kush-Himalaya region, including Nepal and China.

In 1981, a glacial lake outburst flood in the river basin washed away several bridges, including the China-Nepal Friendship Bridge along the Araniko Highway, said Pradeep K. Mool, a glaciologist at ICIMOD in Kathmandu.

Until 2010, floods could strike the villages with no warning. Residents had virtually no time to move to higher ground and were forced to leave behind their livestock and crops, suffering financial losses as well as emotional distress.

“Before the advent of the warning system … we were at risk of being washed away,” said Newar.

Janak Raj Pant, maintenance manager at the Bhote Koshi power plant, said that the river is subject to erratic flows, particularly during the monsoon. For this reason, the power company arranged for the early warning system to be installed in 2010 to benefit the downstream communities in Sindhupalchowk district.

5 TO 8 MINUTES WARNING

The early warning system gives villagers 5-8 minutes’ notice of a flood – just enough time to save themselves.

Five flood sensors are positioned near the Nepal-China Friendship Bridge, about 6 km upstream from the power station.

If the water in the river reaches a dangerous level, the sensors activate sirens placed at four locations, including one at the power plant. The sirens warn the communities to flee to higher ground. Residents use their mobile phones to warn other villages further downstream.

According to Pant, a glacial lake outburst flood takes about five minutes to travel from the Nepal-China Friendship Bridge to the plant. He says lives can be saved if people respond to the alarm immediately.

“At present, the warning system can make the sirens blare five minutes before any flood can strike any of the 79 downstream villages of Sindhupalchowk district,” said Pant, standing beneath the red siren mounted on a side wall of the company’s building.

According to Pant, it is not currently possible to give more warning because information on flooding is not available from the Chinese side of the border.

About 40 percent of the Bhote Koshi river basin is in Nepal, with the remaining 60 percent in China.

Other residents of Jhirpu Phulpingkatti agree that the system has given them a sense of security, but they would like the lead time given by the alarm to be extended.

More sensors need to be placed further upstream within Nepal, especially at glacier snouts and where glacial lakes have formed or are forming, commented Joydeep Gupta, a New Delhi-based journalist and expert on South Asia river basins and flood warning systems.

NEED FOR CHINESE HELP

The ICIMOD study shows that Nepal has experienced at least 24 glacial lake outburst floods. Of these, 14 are believed to have occurred in Nepal itself, and 10 were the result of flood surge overspills from the Chinese side of the border. According to data from the Nepal Meteorological Department, such floods occur on average once every three years in Nepal.

The glaciers in the Hindu Kush-Himalayas are retreating, which scientists believe is the result of climate warming. As glaciers melt, the water released into lakes can build pressure on the natural dams and increase the risk of an outburst flood.

“We have already sought proposals from interested firms to expand the warning system to other vulnerable districts (near) the Bhote Koshi River,” said Pant. “It is hoped that in coming months we should be able to install alarm systems in as many districts as possible.”

“(The) Nepali government should also replicate and establish such early warning systems at all streams to (avoid) or reduce loss of lives or damage,” said Gupta.

But priority should be given to the streams emanating from the unstable glacier lakes identified by ICIMOD in its recent study, he emphasised. According to Gupta, China, as the upstream country, should collaborate with Nepal to share information about flash floods or glacial lake outburst floods hours before they reach the Nepali border, to allow maximum time for warnings to vulnerable downstream communities.

“Any viable information-sharing system by which Chinese officials can pre-inform their Nepali counterparts of any risk of flash flood or (glacial lake outburst flood) would be very helpful. A similar system between China and India already saved many lives in a flash flood in the Sutlej river area a few years ago,” he said.

Saleem Shaikh and Sughra Tunio are climate change and development reporters based in Islamabad.

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