Modeling snowmelt-runoff under climate scenarios in the Hunza River basin, Karakoram Range, Northern Pakistan Adnan Ahmad Tahir a,⇑ , Pierre Chevallier a , Yves Arnaud b , Luc Neppel a , Bashir Ahmad c a Laboratoire Hydrosciences, UMR 5569 – CNRS, IRD, Montpellier Universities 1 & 2, CC57, Université Montpellier 2, 34095 Montpellier Cedex 5, France b Laboratoire d’étude des Transferts en Hydrologie et Environnement, UMR 5564 – CNRS, IRD, Grenoble University 1, Grenoble INP, LGGE, 54 rue Molière, Domaine Universitaire, BP 96, 38402 Saint Martin d’Hères Cedex, France c Director (Environment), Natural Resources Division, Pakistan Agricultural Research Council, G1/5, Islamabad, Pakistan article info Article history: Received 24 January 2011 Received in revised form 25 July 2011 Accepted 1 August 2011 Available online 23 August 2011 This manuscript was handled by Konstantine P. Georgakakos, Editor-in-Chief, with the assistance of Ana P. Barros, Associate Editor Keywords: Upper Indus River Basin (UIB) Hunza River basin MODIS Water resources management Snowmelt-Runoff Model Climate change summary A major proportion of flow in the Indus River is contributed by its snow and glacier-fed river catchments situated in the Karakoram Range. It is therefore essential to estimate the snowmelt runoff from these catchments (with no or scarce precipitation records) for water resources management. The snowmelt runoff model (SRM) integrated with MODIS remote-sensing snow cover products was selected to simu- late the daily discharges and to study the climate change impact on these discharges in the Hunza River basin (the snow- and glacier-fed sub-catchment of the Indus River). The results obtained suggest that the SRM can be used efficiently in the snow- and glacier-fed sub-catchments of the Upper Indus River Basin (UIB). The application of the SRM under future climate (mean temperature, precipitation and snow cover) change scenarios indicates a doubling of summer runoff until the middle of this century. This analysis suggests that new reservoirs will be necessary for summer flow storage to meet with the needs of irriga- tion supply, increasing power generation demand, flood control and water supply. Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction The economy of Pakistan, an agriculture-based country, is highly dependent on the Indus irrigation system. The Indus River is one of the major water carriers of South Asia emerging from the Tibetan Plateau and the Himalayas. It has a controlling storage at Tarbela (Fig. 1) as the river leaves the mountains. Tarbela is the first major structure on the Indus River and supplies the flow to the Indus Irrigation System to irrigate the agricultural lands of Punjab and Sindh (provinces of Pakistan), the dominant producer of agri- cultural products in the country. Inflow to Tarbela is measured at Besham Qila (Indus basin area at Besham = 201,388 km 2 ), situated approximately 80 km upstream of Tarbela (Fig. 1), with a mean an- nual flow of 2410 m 3 /s according to the SWHP (Surface Water Hydrology Project) flow records from 1969 to 2008. The catchment area upstream of Tarbela reservoir is called the Upper Indus Basin (UIB) (Fig. 1), which contributes the major part of inflow into the Indus River from high elevations as a result of snow and glacier melt. The active hydrological zone of the Upper Indus Basin lies in the high-altitude Himalaya and Karakoram Ranges. Several authors (Archer and Fowler, 2004; Hewitt et al., 1989; Wake, 1989; Young and Hewitt, 1990; Bookhagen and Burbank, 2010) reported that more than 65% of the annual flow of the Upper Indus River is con- tributed by the seasonal and permanent snowfields and glacierized areas above 3500 m in elevation. Liniger et al. (1998) stated that some 90% of the lowland flow of the Indus River System originates from the Hindukush, Karakoram and western Himalaya mountain areas. The management of Tarbela reservoir depends to a large extent on the summer inflow contributed by the snow- and glacier-fed tributaries situated in the Karakoram Range. The presence of snow in a basin strongly affects the moisture that is stored at the surface and is available for future runoff (Maurer et al., 2003). The summer runoff is highly correlated with the summer mean temperature in these high-altitude sub-catchments of the UIB, mostly covered with permanent snow pack and glaciers (Archer, 2003). The Hunza 0022-1694/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jhydrol.2011.08.035 ⇑ Corresponding author. Tel.: +33 467 14 90 64; fax: +33 467 14 47 74. E-mail addresses: tahir@msem.univ-montp2.fr, uaf_adnan@hotmail.fr (A.A. Tahir), pierre.chevallier@ird.fr (P. Chevallier), yves.arnaud@ird.fr (Y. Arnaud), neppel@msem.univ-montp2.fr (L. Neppel), bashirad@hotmail.com (B. Ahmad). Journal of Hydrology 409 (2011) 104–117 Contents lists available at SciVerse ScienceDirect Journal of Hydrology journal homepage: www.elsevier.com/locate/jhydrol