Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Hydrol. Earth Syst. Sci. Discuss., 9, 29–64, 2012 Hydrology and www.hydrol-earth-syst-sci-discuss.net/9/29/2012/ Earth System HESSD doi:10.5194/hessd-9-29-2012 Sciences © Author(s) 2012. CC Attribution 3.0 License. Discussions 9, 29–64, 2012 This discussion paper is/has been under review for the journal Hydrology and Earth System Trends for snow Sciences (HESS). Please refer to the corresponding final paper in HESS if available. cover and river flows in the Pamirs (Central Asia) Trends for snow cover and river flows in P. Chevallier et al. the Pamirs (Central Asia) Title Page P. Chevallier1, B. Pouyaud1, M. Moja¨ısky2, M. Bolgov3, O. Olsson4, M. Bauer5, Abstract Introduction 6 and J. Froebrich Conclusions References 1 Laboratoire Hydrosciences, UMR5569, CNRS – IRD – Universites´ Montpellier 1 & 2, Tables Figures Maison des Sciences de l’Eau, CC 57, 34095 Montpellier Cedex 5, France 2VERSeau Developpement,´ 859, rue Jean-Franc¸ois Breton, 34093 Montpellier Cedex 5, France J I 3Water Problem Institute, Russian Academy of Sciences, GSP-1, Gubkin St. 3, IWP RAN, J I 119997 Moscow, Russia 4 Institute of Sustainable and Environmental Chemistry, Leuphana Universitat¨ Luneburg,¨ Back Close Scharnhorststraße 1, 21335 Luneburg,¨ Germany 5Project Management Agency Karlsruhe, Water Technology and Waste Management Full Screen / Esc (PTKA-WTE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany Printer-friendly Version 6Center for Water and Climate, Alterra Wageningen UR, P.O. Box 47, 6700 AA Wageningen, The Netherlands Interactive Discussion 29 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | HESSD Received: 5 December 2011 – Accepted: 22 December 2011 – Published: 3 January 2012 9, 29–64, 2012 Correspondence to: P. Chevallier ([email protected]) Published by Copernicus Publications on behalf of the European Geosciences Union. Trends for snow cover and river flows in the Pamirs (Central Asia) P. Chevallier et al. Title Page Abstract Introduction Conclusions References Tables Figures J I J I Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion 30 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract HESSD In the often discussed Aral Sea basin (Central Asia), water availability depends essen- tially on the high mountains located in its eastern part, especially from the Pamir Alay 9, 29–64, 2012 Range where the Vakhsh and Pyandj Rivers, the main tributaries of the Amu Darya 5 River, flow. In this region, the cryosphere, glaciers, and snow cover significantly im- Trends for snow pact the water cycle and the flow regime, which could be deeply modified by climate cover and river flows change. The present study, part of a project funded by the EU FP6, analyzes the hydro- in the Pamirs (Central 2 logical situation in six benchmark basins covering areas between 1800 and 8400 km , Asia) essentially located in Tajikistan, with a variety of topographical situations, precipitation 10 amounts, and glacierized areas. Four types of parameter are discussed: temperature, P. Chevallier et al. glaciers, snow cover, and river flows. Two time periods are considered: (i) a long time series ending in the 1990s with the collapse of the Soviet Union and based on field observations and data collection; (ii) a May 2000 to May 2002 interval, using scarce Title Page monitored data and satellite information to follow snow cover dynamics. The results Abstract Introduction 15 confirm the global homogeneous trend of temperature increase in the mountain range and its impacts on the surface water regimes. Concerning the snow cover, significant Conclusions References differences are noted regarding the location, the elevation, the orientation and the mor- Tables Figures phology of the respective basins. Finally the expected changes in the flow river regime are regulated by the combination of the snow cover dynamics and the increasing trend J I 20 of the air temperature. It confirms the high sensitivity of this region to the warming as identified by the 4rd IPCC Assessment Report. J I Back Close 1 Introduction Full Screen / Esc The Aral Sea Basin in Central Asia is one of the crisis regions worldwide where the management of water resources is unsustainable, uneconomic and hampered by its Printer-friendly Version 25 cross border extension (Micklin, 1988, 2002; Letolle´ and Mainguet, 1993; Dukhovny and Avakyan, 2001). The collapse of the Soviet system created new and very serious Interactive Discussion 31 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | risks and security challenges for the independent states: Afghanistan, Kazakhstan, Kyrgyzstan, Uzbekistan, Tajikistan, and Turkmenistan (Fig. 1). These challenges in- HESSD volved the disintegration of the water, energy and food sectors and dependence on the 9, 29–64, 2012 now transboundary water resources (Wegerich, 2004, 2008) 5 Although, already special attention was given to the impacts of global changes and associated adaptation issues, including energy and economic approaches (Froebrich Trends for snow et al., 2007; Wegerich et al., 2007; Savitskiy et al., 2008; Olsson et al., 2009) the impact cover and river flows of climate change on the different aspects of local hydrology of the upper Amu Darya in the Pamirs (Central catchment is unidentified. However, the timing of water availability and quantitative Asia) 10 estimates of hydrologic effects of climate change are essential for solving the local water conflicts in the Amu Darya Basin. Additionally, a rapid recession of glaciers and P. Chevallier et al. their contributions to current runoff could lead to a progressive reduction of the already scarce resources and therefore increase the potential for conflict (Olsson et al., 2010). Title Page Global changes, most particularly climate change, have a very important impact on 15 water availability in the Aral Sea basin because of the basin’s particular features. Both Abstract Introduction of the main rivers, the Syr Darya River in the north and the Amu Darya River in the south (Fig. 1), flow down from the west side of the Pamir and Tien Shan mountains Conclusions References through the large and almost desert plain of Kyzylkum, where precipitation is very low, Tables Figures generally below 200 mm yr−1, and summer evaporation is intense. This means that the 20 main part of the flow depends on precipitation, liquid (rainfall) or solid (snowfall) in the J I mountain areas. In such context, the present paper aims to analyze in the upper basin of Amu Darya J I River the trends of the snow cover extent and of the river flow regimes. Back Close Full Screen / Esc 2 Regional settings 25 The chosen study area is centered on the Vakhsh and Pyandj river basins, which are Printer-friendly Version the main headwater tributaries of the Amu Darya River, the largest in Central Asia Interactive Discussion (Academiya Nauk Tadjikskoy SSR, 1968). Its basin (Fig. 1) comprises 309 000 km2 32 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and is shared by Afghanistan and four Central Asia Republics: Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan. HESSD The Vakhsh River, also known as “Kyzyl-Suu” in Kyrgyzstan and as “Surkhob” 9, 29–64, 2012 in north-central Tajikistan, originates in the alpine regions of the Pamir Alai in the 5 south-east of Kyrgyzstan. It flows from north-central Kyrgyzstan to the south-west of Tajikistan. The largest tributaries of the Vakhsh River are the Miksu and the Obi- Trends for snow hingou Rivers. The Pyandj River originates in the Vakjdjir Pass and forms the border cover and river flows between Afghanistan and Tajikistan. The tributaries of the Pyandj River are located in the Pamirs (Central in Afghanistan and Tajikistan. Giese et al. (2004) report an annual mean discharge Asia) 3 −1 3 −1 10 of 20.0 km yr for the Vakhsh River and a mean discharge of 34.3 km yr for the Pyandj River. Hence, both rivers contribute over 65 % to the total mean discharge of P. Chevallier et al. the Amu Darya River (79.3 km3 yr−1). In their upper part, both rivers drain the Pamirs, which are the northern prolongations Title Page of the Hindu Kush and Karakoram mountain ranges. The elevation is quite high, with 15 large areas higher than 4000 m above sea level. Some peaks reach 7000 m a.s.l. such Abstract Introduction as the Ismoil Somoni Peak (former Peak of Communism, 7495 m a.s.l.) and the Ibn Sina Peak (former Lenin Peak, 7134 m a.s.l.). This region is rich in glaciers (Dyurgerov Conclusions References and Meier, 2005), containing the Fedchenko Glacier, the longest in Eurasia (77 km). Tables Figures The climate is continental under the influence of the Westerlies, with very high local 20 contrasts due to the orographic conditions. Figures 2 and 3 present the annual distribu- J I tion of precipitation and temperature (Williams and Konovalov, 2008) over the studied region delimited by the 70th to 74th meridians and 37th to 40th parallels. For precip- J I itation (Fig. 2), a significant contrast appears between the area located in the north- Back Close west from the 72nd meridian and 38th parallel, with values above 600/700 mm yr−1 25 and those located in the south and east with arid conditions and values in some places Full Screen / Esc below 100 mm yr−1. The highest amount of precipitation in the region is recorded at the Fedchenko Glacier station. For the whole area, the distribution of precipitation presents Printer-friendly Version a maximum during the winter and early spring and a minimum during the summer and early autumn. The temperature (Fig. 3) in the region globally presents large seasonal Interactive Discussion 33 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | amplitude, the extreme values depending essentially on elevation, which gradually in- creases from west to east.