Geographica Augustana - Institut für Geographie und ...

Regional isotope patterns and hydrograph separation of an ungauged basinin Central AsiaChristiane Meier 1 , M. Knoche 1 , M. Weiler 2 , R. Merz 1 & S. M. Weise 11UFZ - Helmholtz-Zentrum für Umweltforschung GmbH2 Albert-Ludwigs-Universität Freiburg, Institut für Hydrologie1. IntroductionWater scarcity is a well known problem in wide parts of the world. Also the Central Asian lowlands,which receive their water from large rivers as the Panj and Amu Draya, are affected by watershortage amongst others due to excessive irrigation purposes. These river systems are mainly fedfrom snow- and glacial melt occurring in the Pamir and Tien Shan mountains (Barlow and Tippett,2008). The Pamir region is influenced both by the Westerlies and by the Monsoon (Aizen et al.,2009).We want to identify and quantify the runoff components of one characteristic large headwaterstream (Gunt, 14,000 km²) by using the stable isotopes of water and additionally hydrochemicaldata to clarify the sources of precipitation and the importance of climate change on the waterbalance of this region. These are to be used for calibration and validation of a hydrological model ofthe catchment.2. Study AreaThe Gunt catchment is an east-west running basin with an altitude range of about 4,000 m (Fig. 1)with the highest elevations, Peak Karl Marx (6,726 m) and Peak Engels (6,510 m), at its southernborder. Almost in the middle of the catchment there is a natural dammed lake (Yashilkul) situatedwith an extension of circa 40 km².The western part of the catchment is characterized by steep erosion valleys, while the ast representsa high glacier formed cold arid plateau.23