Environmental hydrochemical and stabile isotope methods used to characterise the relation between karst water and surface water

Karst aquifers are characterized by high heterogeneity of groundwater flow. The classical study methods such as boreholes, pumping tests, and point observations give important data but cannot be extended to the entire aquifer. However the environmental hydrochemical and stabile isotope methods could give important information about large scale aquifer characterization. Some study examples from Albania, shown in this paper, demonstrate the successful application of the isotope methods, which are more powerful if applied in combination with hydrochemical ones, for the identification of the karst water recharge sources. Among the isotope methods the altitude effect seems to be more indicative for the solution of the problem concerned. For characterising the lithology of karst rocks and the physical aspects of karst aquifers (type of groundwater flow) the combined use of some hydrochemical parameters like the water conductivity, total hardness, ionic ratios rCa/ rMg, rSO₄/r/mg, CO₂ pressure and the indexes of calcite and (Si_c) and of dolomite saturation (Si_d), result very useful.