Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes
November
Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes
A. F. Lutz 0 1
W. W. Immerzeel 0 1
P. D. A. Kraaijenbrink 1
A. B. Shrestha 1
M. F. P. Bierkens 1
0 FutureWater , Costerweg 1V, 6702 AA, Wageningen , The Netherlands , 2 Utrecht University, Department of Physical Geography , PO Box 80115, 3508 TC, Utrecht , The Netherlands , 3 International Centre for Integrated Mountain Development , GPO Box 3226, Khumaltar, Kathmandu , Nepal
1 Editor: Juan A. Añel, Universidade de Vigo , SPAIN
The Indus basin heavily depends on its upstream mountainous part for the downstream supply of water while downstream demands are high. Since downstream demands will likely continue to increase, accurate hydrological projections for the future supply are important. We use an ensemble of statistically downscaled CMIP5 General Circulation Model outputs for RCP4.5 and RCP8.5 to force a cryospheric-hydrological model and generate transient hydrological projections for the entire 21st century for the upper Indus basin. Three methodological advances are introduced: (i) A new precipitation dataset that corrects for the underestimation of high-altitude precipitation is used. (ii) The model is calibrated using data on river runoff, snow cover and geodetic glacier mass balance. (iii) An advanced statistical downscaling technique is used that accounts for changes in precipitation extremes. The analysis of the results focuses on changes in sources of runoff, seasonality and hydrological extremes. We conclude that the future of the upper Indus basin's water availability is highly uncertain in the long run, mainly due to the large spread in the future precipitation projections. Despite large uncertainties in the future climate and long-term water availability, basin-wide patterns and trends of seasonal shifts in water availability are consistent across climate change scenarios. Most prominent is the attenuation of the annual hydrograph and shift from summer peak flow towards the other seasons for most ensemble members. In addition there are distinct spatial patterns in the response that relate to monsoon influence and the importance of meltwater. Analysis of future hydrological extremes reveals that increases in intensity and frequency of extreme discharges are very likely for most of the upper Indus basin and most ensemble members.
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Funding: This study was undertaken under the
Indus Basin Programme of ICIMOD, funded in part
by the United Kingdom's Department for
International Development (DFID), through their
financial support of core research at ICIMOD. This
work is partly carried out by the Himalayan
Adaptation, Water and Resilience (HI-AWARE)
consortium under the Collaborative Adaptation
Research Initiative in Africa and Asia (CARIAA) with
financial support from the United Kingdom's
Department for International Development (DFID)
Introduction
The water resources supplied by the upper Indus basin (UIB) are essential to millions of people
and future changes in both demand and supply may have large impacts [
1
]. The UIB provides
water for the world's largest continuous irrigation scheme through several large reservoirs (e.g.
and the International Development Research
Centre (IDRC), Ottawa, Canada. This project has
received funding from the European Research
Council (ERC) under the European Union's Horizon
2020 research and innovation programme (grant
agreement 676819). In addition, this work was
partially supported by core funds of ICIMOD
contributed by the governments of Afghanistan,
Australia, Austria, Bangladesh, Bhutan, China,
India, Myanmar, Nepal, Norway, Pakistan,
Switzerland, and the United Kingdom. DFID partly
funds ICIMOD's Indus Basin Programme, under
which this study was undertaken. These funds
partly supported the contributions of AFL, WWI
and ABS. DFID and IDRC funds the HI-AWARE
consortium, of which ICIMOD and FutureWater are
consortium members. These funds partly
supported the contributions of AFL, WWI and ABS.
ERC partly funded the contribution of WWI through
grant agreement 676819. ICIMOD core funds
partly funded the contribution of ABS. AFL and
WWI are employed by FutureWater. FutureWater
provided support in the form of salaries for authors
AFL and WWI, but did not have any additional role
in the study design, data collection and analysis,
decision to publish, or preparation of the
manuscript. The specific roles of these authors are
articulated in the `author contributions' section.
Competing Interests: We have read the journal's
policy and the authors of this manuscript have the
following competing interests: AFL and WWI are
employed by FutureWater. There are no patents,
products in development or marketed products to
declare. This does not alter our adherence to all the
PLOS ONE policies on sharing data and materials.
the Tarbela and Mangla dams, Fig 1), which depend for more than 50% of their annual inflow
on snow and glacier melt water [
2–5
]. In combination with varia (...truncated)