Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model

Pauritsch, Marcus; Wagner, Thomas; Winkler, Gerfried; Birk, Steffen

Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model | Etude des composantes d’écoulement des eaux souterraines dans des glaciers alpins de reliquats rocheux (Autriche) en utilisant un modèle numérique La investigación de componentes de flujo de agua subterránea en un glaciar rocoso relicto Alpino (Austria) utilizando un modelo numérico 利用数值模型研究阿尔卑斯山脉(奥地利)残余岩石冰川地下水流成分 Investigação dos componentes do fluxo da água subterrânea em geleiras Alpinas de rochas relictas (Áustria) utilizando um modelo numérico

2017

Pauritsch, Marcus | Wagner, Thomas | Winkler, Gerfried | Birk, Steffen

Relict rock glaciers are complex hydrogeological systems that might act as relevant groundwater storages; therefore, the discharge behavior of these alpine landforms needs to be better understood. Hydrogeological and geophysical investigations at a relict rock glacier in the Niedere Tauern Range (Austria) reveal a slow and fast flow component that appear to be related to the heterogeneous structure of the aquifer. A numerical groundwater flow model was used to indicate the influence of important internal structures such as layering, preferential flow paths and aquifer-base topography. Discharge dynamics can be reproduced reasonably by both introducing layers of strongly different hydraulic conductivities or by a network of highly conductive channels within a low-conductivity zone. Moreover, the topography of the aquifer base influences the discharge dynamics, which can be observed particularly in simply structured aquifers. Hydraulic conductivity differences of three orders of magnitude are required to account for the observed discharge behavior: a highly conductive layer and/or channel network controlling the fast and flashy spring responses to recharge events, as opposed to less conductive sediment accumulations sustaining the long-term base flow. The results show that the hydraulic behavior of this relict rock glacier and likely that of others can be adequately represented by two aquifer components. However, the attempt to characterize the two components by inverse modeling results in ambiguity of internal structures when solely discharge data are available.

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