Mountain Pakistan walls off glacial lake flash floods
BAGROT VALLEY: Nestled at the foot of five snow-capped mountain peaks in Pakistan’s northern Gilgit-Baltistan province, the villages of the Bagrot valley face fearsome flooding risks.
As glaciers retreat, they leave behind lakes supported by ice dams or accumulations of rock and soil. Inherently unstable, these dams often burst, sending huge volumes of water rushing into the villages below them. But a project to build protective structures around vulnerable villages has found a way to lessen the risks and the damage.
“Outbursts can trigger a release of millions of cubic metres of water and debris in a few hours,” said Khalil Ahmed, national manager of the Pakistan GLOF (Glacial Lake Outburst Flood) project. But walls can help divert the water, he said.
The four-year, $7.6 million project, which focuses on Bagrot valley in Gilgit-Baltistan and Bindo Gol valley in the northwestern Khyber-Pakhtunkhwa province, has since 2011 built flood diversion walls around more than 10 vulnerable villages. Some of the barriers are made up of concrete steps, while others use stone-filled wire-mesh cages to divert floodwater, debris and ice away from buildings and land and instead direct it into the rivers flowing through the valleys.
With funding and logistical support from the UN’s Adaptation Fund, the United Nations Development Programme (UNDP) and the Pakistan government, the project is already producing promising results, experts say.
When a glacial lake burst in April 2014 and another in July 2015, both triggering flash floods in the Bagrot valley, the walls saved village properties and maize and vegetable crops from being washed away, said Shahadat Noor, a potato farmer in Bagrot. “The structures veered the floodwater flow off the settlements and croplands, sending it gushing safely through the valley,” he told Thomson Reuters Foundation. Local people say the project has also helped mountain communities regain confidence in their ability to withstand such floods. “We do know we cannot control glacial melt and erratic or intense rains,” said Mazhar Hussain, a community development specialist who runs the Dubani Development Organisation, which works on the Pakistan GLOF Project. “But we can, at least, minimise the risk of GLOF, (flash) floods, landslides or land erosion by adapting to the impacts of global warming on the valley’s glaciers,” he said.
As well as bolstering Bagrot’s defences against glacial flooding, said Hussain, the project has designated nine safe havens from flooding: high, open and flat areas, equipped with toilets and access to drinking water, that villagers can use as temporary shelters when floods hit.
Over the last three years, construction on such defences has begun in 15 different Bagrot mountain villages identified by the communities as vulnerable to glacial lake outburst floods or flash flooding, Hussain added.
Sajid Ali, a young farmer in the Bagrot valley, said his village used to fear flash floods that threatened to sweep away homes, farm plots and centuries-old irrigation channels. “But such is the case no more,” he said, standing in the shadow of the Hinarchi glacier.
According to the Pakistan Meteorological Department, in 2010 there were about 2,400 glacier lakes in Pakistan’s north. Now there are over 3,000, according to the department, and the number is expected to keep growing as temperatures continue to rise, summers grow longer and warmer, and winters get shorter.
Ghulam Rasul, the meteorological department’s director-general and former senior climatologist, said more than seven glacial lake outbursts have been recorded in the last two years in the country’s north. The department currently has 52 glacial lakes in the north flagged as likely to burst at any time, he said.
And the problem isn’t limited to Pakistan. Nepal, Bhutan and India are also critically vulnerable to glacial lake outburst floods and flash floods, climatologists say.
In June 2013, devastating flooding in the northern Indian state of Uttarakhand killed more than 5,000 people, and the Sunkoshi landslide tragedy in Nepal in August 2014 left at least 150 dead.
Climatologists at Pakistan’s Global Change Impact Studies Centre (GCISC) and the Pakistan Meteorological Department warn that as the number of glacial lakes continues to grow, outbursts will be hard to avoid. The focus should be on finding ways to protect communities from the inevitable, they say.
Replicating the measures in the Bagrot valley could “help stave off loss of life and livelihoods in the mountain communities and downstream areas,” said Munir Sheikh, former head of climatology and environment at the impact studies centre in Islamabad.