Indus basin glaciers reveal mountain precipitation twice as high पर्यावरण बदलाव से हो रहा है उत्तराखंड के ग्लेशियर्स में परिवर्तन?

Indus basin glaciers reveal mountain precipitation twice as high पर्यावरण बदलाव से हो रहा है उत्तराखंड के ग्लेशियर्स में परिवर्तन?


Uttarakhand too has a number of glaciers, some of which are under observation by glaciologists and hydrologists. With food production, livelihood, tourism and so many other things dependent on glaciers and snow, impacts due to changing climate need to be carefully monitored, writes Nivedita Khandekar


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he amount of snow and rain in the Himalayas is about twice as high as commonly assumed. These findings of the research in the Indus basin by scientists can have an important bearing for water management and climate change impact assessment given the fact that millions of people across South Asia are dependent on major rivers arising out of the Himalayas.

Himalayan glaciers cover about 17 % of the mountain area as compared to 2.2% in the Swiss Alps. This is the largest body of ice outside the polar region and hence called the ‘third pole’. These glaciers are a perennial source of water for a number of major rivers, including Indus, Ganga and Brahmaputra, lifeline for South Asian countries such as Pakistan, Nepal, Bhutan, India and Bangladesh. Increased precipitation and shift in snowfall pattern is already an indicator of the impact of climate change. Mitigating the impact of and adaptation for the climate change can be planned if the water availability (and hence a possibly flood after glacier lake burst) are known.

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Mighty Himalayan range (Photo by Uttarakhand Panorama)


But above all, glaciers are a perennial source of water and very sensitive to the climate. Advancing and shrinking glaciers is affected by and in turn affects the environment. But right now it is not known how much snow and rain falls in these vast mountain ranges.

Lack of observation and inaccessibility of terrain, as most glaciers are at an altitude of 12,000 feet and above, has meant non-availability of data. The study “Reconciling high-altitude precipitation in the upper Indus basin with glacier mass balances and runoff” (http://www.hydrol-earth-syst-sci.net/19/4673/2015/hess-19-4673-2015.pdf) published in ‘Hydrology and Earth System Sciences’ journal on November 26, 2015 attempts to make an estimate.

Authors W W Immerzeel, N Wanders, A F Lutz, J M Shea and M F P Bierkens came from Department of Physical Geography, Utrecht University, Utrecht, the Netherlands; Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA; FutureWater, Wageningen, the Netherlands; and the International Centre for Integrated Mountain Development (ICIMOD), Kathmandu, Nepal.

ICIMOD is a regional intergovernmental learning and knowledge sharing centre serving the eight regional member countries of the Hindu Kush Himalayan (HKH) region – Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal and Pakistan – with an aim to influence policy and practices to meet environmental and livelihood challenges emerging in the HKH region. FutureWater is a research and consulting organization that works throughout the world to combine scientific research with practical solutions for water management.

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Indus in the Ladakh region (Photo by Uttarakhand Panorama)

 

WHAT WAS THE STUDY ABOUT?


The field chosen was the upper Indus basin, which is supposedly very dry and yet has the largest glaciers outside the polar region. Explained Walter Immerzeel of Utrecht University and a visiting scientist at the ICIMOD, “This seemed contradictory and gave us the idea for this study. We calculated how much precipitation is required to sustain those large glaciers and the results were spectacular. In the most extreme case, a more than tenfold amount of snow is required than what was previously thought.”

Satellite observations were combined with a computer model and observations from the ground for the study. But there is a limit up to which humans can reach the high altitude for regular measurements. (Continued exposure to higher altitudes can be a health hazard or at times can even be fatal.) Satellite images are not of sufficiently high resolution and even quality to capture spatial variation and magnitude of mountain precipitation. So, in the absence of snow and rain data from high altitude for the Indus, the scientists needed some other way.

The team used the glacier mass balance to inversely infer the high altitude precipitation in the upper Indus basin and show that the amount of precipitation required to sustain the observed mass balance of large glacier system is far beyond what is observed at the valley stations or estimated by gridded precipitation products.

“We used observations of the river flow and the results confirmed that the amount of water in the rivers can only be explained if the amount of snow and rain is as high as we estimated. An independent validation with observed river flow confirms that the water balance can indeed only be close when the high altitude precipitation on average is more than twice as high and in extreme cases up to a factor of 10 higher than previous thought,” he said.

This is huge.

The Indus basin irrigation scheme is considered as the largest in the world. It is fed primarily by melt water. “Since so much of food production in the Indus depends on glaciers and snow, this shows again how sensitive this area is to climate change,” said Marc Bierkens, professor of Hydrology at Utrecht University, adding, “Our findings will have important bearing on climate change impact studies and water management in this important transboundary river basin.”

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Extreme weather led to Uttarakhand flash-floods in 2013 that caused many death and badly impacted its economy.   (Photo: Uttarakhand Panorama)


WHAT DOES THIS MEAN FOR UTTARAKHAND?


The Geological Survey of India has listed about 9,575 glaciers in the Indian Himalayas. Of these, only about 267 are over 10 sq kms. Mass balance of a glacier gives the quantum of water availability in that glacier system. In simple terms, it is the difference between accumulation of snow in winter and loss of snow and ice in summer. This snow melt contributes directly to the stream run off.

Although Uttarakhand does not have as big a basin as that of Indus, but the state has rivers Ganga and Yamuna, two of the majors, originating from glaciers and also several other glacier fed rivers. As per the Uttarakhand government’s own data (http://uttarakhandtourism.gov.in/utdb/?q=mountains-glaciers), major glacial formations of Garhwal include Bandarpunch, Doonagiri, Khatling, Gangotri and the Nanda Devi cluster of glaciers while Kumaon incorporates the Kaphni, Milam, Pindari and Ralam glaciers. These glaciers feed not just the Ganga and Yamuna but also Bhagirathi and a number of other tributaries and dis-tributaries such as Dhauli Ganga, Kali Ganga, Girthi Ganga, Rishi Ganga, Bal Ganga, Bhilangna, Tons, Alaknanda, Nandakini, Pindar, Kosi and Mandakini.

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Gomukh Glacier (Photo by Nivedita Khandekar)


If as per this ICIMOD study, the amount of snow and rain in the Himalayas is about twice as high as commonly assumed, it can have huge implications for the state.

Already in 2013, it was witnessed how the entire Bhairon Ghati and the Kedar Ghati received massive rains and snow fall in higher altitudes. The possible repeat of such large scale devastation are uncertain but the state machinery needs to be prepared for all kinds of eventualities. The Uttarakhand glaciers too need to be studied and adequate data needs to be generated.

Changing climate is evident on a day to day basis. The mankind that basically accelerated it needs to gear up for it.


nivedita

Nivedita Khandekar is a Delhi-based independent journalist who writes on environmental, climate change and developmental issues.

She can be reached at nivedita_him@rediffmail.com and you can follow her on Twitter at @nivedita_Him


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