Geographica Augustana - Institut für Geographie und ...

Fig. 1: Map showing the study area – Gunt catchment – with sampling points for hydrologicalmonitoring3. First Resultsa) Regional Isotope PatternsAs a first step towards estimation of the origin, interaction and dynamics of stream and subsurfacewater components, samples are taken monthly from river water, ground water and precipitation. Wefound temporal and spatial differences in the regional patterns of the distribution of 2 H and 18 Oin water which we link to altitude and continentality.The monitoring data show high 2 H (-103.5 to -96.5 ‰) and 18 O (-14.8 to -14.0 ‰) values far inthe west of the catchment, and the lowest values in the plateau area around the lake Yashilkul andin the east of the catchment ( 2 H: -125.0 to -131.0 ‰, 18 O: -16.0 to -18.0 ‰). This effect resultsfrom the increasing altitude and continentality as well as the decreasing amount of precipitationfrom west to east. The eastern part of the catchment is an cold alpine desert with precipitationsums of ≤ 160 mm/a while the western part is warmer and receives a little more precipitation(~300 mm/a).Further we found out that the isotopic signature of the Gunt River is mainly formed by the lakewater. Especially in the winter months the streamflow is dominated by heavier water (caused byevaporation) flowing through the natural landslide dam and is partly released artificially.An additional pattern, that we identified through the isotopic data, is a distinction betweentributaries flowing from the northern boundary to the main stream and tributaries originating in thesouth of the catchment (Fig. 2). The altitudes of the northern and southern mountain ranges are24