Effect of Alpine karst on the hydrology of the Berchtesgadener Ache basin: a comprehensive summary of karst research in the Berchtesgaden Alps

Abstract

The Berchtesgaden Alps are situated in the Northern Limestone Alps, characterized by individual mountain plateaus and ridges in close proximity to each other, intersected by valleys, with an altitudinal gradient of 2 100 meters. The limestone has been exposed to dissolution processes since the Cretaceous, leading to a massive karstified aquifer with a wide range of subsurface flow channels. There are hundreds of springs as groundwater recharge locations, feeding the seven rivers of the region that contribute to the Danube watershed. Several studies were conducted to examine the hydro-geological conditions and the resulting groundwater flow. This paper aims to evaluate and summarize research in the basin describing groundwater flow to identify the main drainage direction, travel times, spring dynamics and possible subsurface redistribution in the individual mountain ranges and the whole basin. To this end, we evaluate several tracer experiments, two isotope studies and a spring database. The tracer experiments are generating knowledge about flow directions in the individual mountain ranges, groundwater redistribution, water storage and mean travel times. Five experiments prove increased groundwater flow remaining within a valley and four experiments indicate groundwater redistribution through mountain ranges. The isotope studies indicate potential water storage in the Wimbach valley of an estimated 100 x 106 to 470 x 106 m3 and mean transit times of about four years. The analysis of the spring database focuses on locations and discharge classification. Overall, there are 289 springs recorded in the spring database, distributed from 600 to over 2 000 m altitude, with major springs at the northern base of the mountains Hochkalter, Watzmann and at the north shore of lake Königssee. The conclusion summarizes the effect of the karst aquifer on the hydrology of the region. The outlook introduces current research within the area and the distributed water balance modelling.