Resumen
Carbonate rocks cover about 23% of Albania, with exploitable karst water resources estimated at 2.84 × 109 m3/year (about 65% of the total exploitable groundwater resources in the country). The Kruja tectonic zone is characterized by the presence of SE?NW-oriented carbonate structures, rich in fresh and thermal groundwaters. More than 80% of the thermal springs in Albania are present in this tectonic zone. One of its most interesting carbonate structures, with the presence of both cold and thermal waters, is the small karst structure of Makaresh, with a surface of 22 km2. The purpose of this article is to describe the hydrogeological characteristics of this massif; based on the physico-chemical characteristics, groundwaters of the study area are classified as cold waters (belonging to the local flow system) and thermal waters (originating in intermediate/deep flow systems). The former are mainly of HCO3-Ca or HCO3-Ca-Mg type (electrical conductivity 580?650 µS/cm, Temperature 13.9?16.6 °C). Thermal waters are mainly of the Cl-Na-Ca type (EC 7200?7800 µS/cm, T 18.5?22.5 °C); they are further characterized by high hydrogen sulfide concentration, up to about 350 mg/L. The presence of two groundwater types in the Makaresh massif is connected to the presence of two groundwater circulation systems. The main factors of the groundwater physico-chemical quality are the dissolution of rocks and minerals contained therein, the presence of hypogenic speleogenesis, and the mixing of the groundwater of the two systems. The hydrogeological studies proved that karst rocks contain considerable freshwater resources, partly used for water supply. Thermal waters are not currently exploited due to their temperature, but they are potentially suitable for thermal uses by drilling boreholes to a depth of about 1000 m.