Abstract:The results from a hydrological monitoring program of Breelva basin (Spits− bergen, Svalbard) have been analysed to improve the understanding of the Werenskiöld Glacier system's functioning in the High Arctic. Hydrographs of a 44 km 2 river basin (27 km 2 of which was covered by a glacier) were analysed for the period 2007-2012. Sea− sonal discharge fluctuations were linked to glacier ablation and meteorological parameters, including atmospheric circulation types. A dichotomy was found in the discharge peaks generation during the hydrologically active season, with the main role played by snow and ice melt events during its first part and the rainfall regime dominating its second part. Foehn type strong winds played a significant role in the generation of ablation type floods (e.g. in August 2011). A simple classification of the runoff regime was applied to the examined six−year period, resulting in the identification of its three types: the ablation type (dominant in 2007 and 2009), the rainfall type (in the years 2011-2012), and the mixed type (during 2008 and 2010). According to publications the river flow season in Spitsbergen begins in June and end with freeze−up in September or at the beginning of October. Recently, this sea− son for Breelva tend to be extended with the mid−May onset and end in the second part of October. A multiannual trend was noted that reflects a growing importance of rainfalls, especially in September. Rainfall waters play a more distinct role in outflow from the Breelva catchment recently.

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Changes in water chemistry along the High Arctic fluvial-lacustrine system located in Wedel Jarlsberg Land in the SW Spitsbergen (Svalbard) were investigated during the summer season of 2010 and 2011. The newly formed river-lake system consists of three lakes connected with the Brattegg River. The first bathymetric measurements of these lakes were made by the authors in 2010. The Brattegg River catchment represents a partly glaciered Arctic water system. The studied lakes are characterized by low mineralization and temperature of water. The value of the electrolytic conductivity (EC) ranges from 30.2 to 50.5 lS cm -1 and the temperature of surface water from 1.5 to 7.8°C. The temperature increase takes place downstream starting from Upper Lake to the outflow from Myrktjørna Lake. The waters of lakes have higher temperatures than the stream. The predominant ions are HCO 3-(up to 16.5 mg L -1 ), Cl -(6.66-8.53 mg L -1 ), Ca 2? (2.40-4.45 mg L -1 ) and Na ? (2.65-3.36 mg L -1 ). The highest values of ammonium and DOC found in the lowest Myrktjørna Lake seem to be related to the presence of aquatic organisms and also birds. From the group of 10 analyzed microelements, increased concentrations of aluminum, up to almost 500 lg L -1 , are present in the lakes'water. Water isotopic composition ranges for d 18 O and d 2 H, from -10.6 to -10.9% and from -70.8 to -72.3%, respectively. The vertical zonality of lake waters is manifested in a decrease in the temperature and increase in EC and chemical elements concentrations.