H. Oberhänsli*, G. Schettler, N. Stroncik, R. Naumann (GFZ-Potsdam)
St. Weise (UFZ-Halle)
V. Dukhovny, G. Stulina (Scientific-Information Center Interstate Coordination Water Commission, Tashkent)
AA. Mavlonov (Institute of Hydrogeology and Engineering Geology, State Committee of the Republic of Uzbekistan on Geology and Mineral Resources, Tashkent)
*(Principle Investigator: now Museum für Naturkunde, Leibnitz Institut, Humboldt Universität Berlin)
In the Amudarya Delta, there is a distinct salinity contrast between the low-salinity river water (~ 1g/l), low-salinity confined groundwater of Cretaceous aquifers and the salinity of the unconfined groundwater (10 – 95 g/l) and the Aral Sea (~ 100 g/l). During three expeditions between 2009 and 2010, we collected soil/sediments and waters from different compartments (Amudarya, irrigation canals, collectors, salt pans, the shrinking Aral Sea, unconfined GW and confined GW) for chemical analysis, analysis of stable and radiogenic isotopes as well noble gases.
On the basis of the derived data sets we received new insights in the hydrochemical evolution of the regional GW. Our results and models are applicable in other semiarid to arid alluvial basins that receive freshwater inflow from remote (alpine) feeding regions. The overall water balance of the Aral Sea and in particular the role of groundwater input into the lake is a subject of scientific debate. Moreover, up to now the hydraulic impact of the shrinking Aral Sea on the regime of adjacent shallow and deep aquifers is unclear. In water budget models, our results constrain assumptions for the GW-discharge into the Aral Sea.