摘要
In the Northern Calcareous Alps karst springs and wells in porous groundwater bodies are the common sources of drinking water. While karst springs deliver water with short residence times and extreme variabilities in discharge, porous groundwater bodies include high risks of pollution according to intensive agricultural and industrial activities in the catchment areas. As alternative in this densly populated region in Germany and Austria the widespread but rarely used dolomitic unit Hauptdolomit (HD) was investigated. The purpose was to find indications to identify springs and wells dominated by an HD-aquifer and to find significant differences in age distribution and flow rates between HD-aquifers and karstified groundwater bodies. The assumption was that springs in HD-aquifers do not deliver very young waters and so show significantly lower vulnerability to pollution and less variability in discharge because HD features the necessary retention capacity and very slow diffuse flow on micro fissure systems and also exhibits larger fractures for water sampling and conduit flow. The main results of the study were: (1) the structural setting on the surface is not significant for the internal hydro-geological properties, (2) the hydro-chemical signature gives a good evidence to identify an HD-catchment area, (3) the hydrograph curves show significantly less variability which is the most important advantage over karst springs, (4) mean residence times of 2 years to two decades are conducted by an age distribution which ranges very young as well as more than 50 years old components, (5) the amount of water available from the dolomite formation considerably exceeds the predicted requirements.