Unusual catchment runoff in a high alpine karst environment influenced by a complex geological setting (Northern Calcareous Alps, Tyrol, Austria)Außergewöhnlicher Gebietsabfluss in einem hochalpinen Karstgebiet als Folge eines komplexen geologischen Baues (Nördliche Kalkalpen, Tirol, Österreich)Originalité de l’écoulement d’un bassin versant karstique alpin de haute altitude influencé par un cadre géologique complexe (Alpes Calcaires du Nord, Tyrol, Autriche)Escorrentía anómala en un ambiente kárstico alpino influenciado por un medio geológico complejo (Northern Calcareous Alps, Tyrol, Austria)受复杂地质环境影响的高山岩溶环境中的异常集蓄径流(奥地利Tyrol州北部石灰性阿尔卑斯山)Área de contribuição atípica no alto de um ambiente cárstico alpino influenciado por um contexto geológico complexo (Calcários Alpinos do Norte, Tirol, Áustria)

Garber Schlag (Q-GS) is one of the major springs of the Karwendel Mountains, Tyrol, Austria. This spring has a unique runoff pattern that is mainly controlled by the tectonic setting. The main aquifer is a moderately karstified and jointed limestone of the Wetterstein Formation that is underlain by nonkarstified limestone of the Reifling Formation, which acts as an aquitard. The aquifer and aquitard of the catchment of spring Q-GS form a large anticline that is bound by a major fault (aquitard) to the north. Discharge of this spring shows strong seasonal variations with three recharge origins, based on δ18O and electrical conductivity values. A clear seasonal trend is observed, caused by the continuously changing portions of water derived from snowmelt, rainfall and groundwater. At the onset of the snowmelt period in May, the discharge is composed mainly of groundwater. During the maximum snowmelt period, the water is dominantly composed of water derived from snowmelt and subordinately from rainfall. During July and August, water derived from snowmelt continuously decreases and water derived from rainfall increases. During September and October, the water released at the spring is mainly derived from groundwater and subordinately from rainfall. The distinct discharge plateau from August to December and the following recession until March is likely related to the large regional groundwater body in the fissured and moderately karstified aquifer of the Wetterstein Formation and the tectonic structures (anticline, major fault). Only a small portion of the water released at spring Q-GS is derived from permafrost.