Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 19, 4673-4687, 2015
http://www.hydrol-earth-syst-sci.net/19/4673/2015/
doi:10.5194/hess-19-4673-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
26 Nov 2015
Reconciling high-altitude precipitation in the upper Indus basin with glacier mass balances and runoff
W. W. Immerzeel1,3,4, N. Wanders1,2, A. F. Lutz3, J. M. Shea4, and M. F. P. Bierkens1 1Department of Physical Geography, Utrecht University, Utrecht, the Netherlands
2Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
3FutureWater, Wageningen, the Netherlands
4International Centre for Integrated Mountain Development, Kathmandu, Nepal
Abstract. Mountain ranges in Asia are important water suppliers, especially if downstream climates are arid, water demands are high and glaciers are abundant. In such basins, the hydrological cycle depends heavily on high-altitude precipitation. Yet direct observations of high-altitude precipitation are lacking and satellite derived products are of insufficient resolution and quality to capture spatial variation and magnitude of mountain precipitation. Here we use glacier mass balances 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 balances of large glacier systems is far beyond what is observed at valley stations or estimated by gridded precipitation products. An independent validation with observed river flow confirms that the water balance can indeed only be closed 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 previously thought. We conclude that these findings alter the present understanding of high-altitude hydrology and will have an important bearing on climate change impact studies, planning and design of hydropower plants and irrigation reservoirs as well as the regional geopolitical situation in general.

Citation: Immerzeel, W. W., Wanders, N., Lutz, A. F., Shea, J. M., and Bierkens, M. F. P.: Reconciling high-altitude precipitation in the upper Indus basin with glacier mass balances and runoff, Hydrol. Earth Syst. Sci., 19, 4673-4687, doi:10.5194/hess-19-4673-2015, 2015.
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Short summary
The water resources of the upper Indus river basin (UIB) are important for millions of people, yet little is known about the rain and snow fall in the high-altitude regions because of the inaccessibility, the climatic complexity and the lack of observations. In this study we use mass balance of glaciers to reconstruct the amount of precipitation in the UIB and we conclude that this amount is much higher than previously thought.
The water resources of the upper Indus river basin (UIB) are important for millions of people,...
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