Spatial assessment of probable recharge areas – Investigating the hydrogeological controls of an active deep-seated gravitational slope deformation
- 1Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Innrain 25, 6020 Innsbruck, Austria
- 2Department of Geography, University of Innsbruck, Innrain 52f, 6020 Innsbruck, Austria
- 3Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, Netherlands
- 4Institute of Geology, University of Innsbruck, Innrain 52f, 6020 Innsbruck, Austria
- 1Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Innrain 25, 6020 Innsbruck, Austria
- 2Department of Geography, University of Innsbruck, Innrain 52f, 6020 Innsbruck, Austria
- 3Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, Netherlands
- 4Institute of Geology, University of Innsbruck, Innrain 52f, 6020 Innsbruck, Austria
Abstract. Continuous and slow-moving deep-seated landslides entail challenges for the effective planning of mitigation strategies aiming at the reduction of landslide movements. Given that the activity of most of these landslides is governed by pore pressure variations within the shear zone, profound knowledge about their hydrogeological control is required. In this context, the present study presents a new approach for the spatial assessment of probable recharge areas to better understand a slope's hydrogeological system. The highly automated geo-statistical approach allows deriving recharge probability maps of groundwater based on stable isotope monitoring and a digital elevation model (DEM). By monitoring stable isotopes in both, groundwater and precipitation, mean elevations of recharge areas can be determined and further constrained in space with the help of the DEM. The approach was applied to the Vögelsberg landslide, an active slab of a deep-seated gravitational slope deformation (DSGSD) in the Watten valley (Tyrol, Austria). Resulting recharge probability maps indicate that shallow groundwater emerging at springs on the landslide recharges between 1100–1500 m a.s.l.. In contrast, groundwater encountered in wells in up to 49 m below the landslide’s surface indicates a mean recharge elevation of up to 2200 m a.s.l. matching the highest parts of the catchment. Further inferred proxies, including flow path length, estimated recharge area sizes, and mean transit times of groundwater validated against field measurements of electrical conductivity, water temperature, and discharge resulted in a profound understanding of the hydrogeological driver of the landslide. It is shown that the new approach can provide valuable insights into the spatial pattern of probable recharge areas where mitigation measures aiming at reducing groundwater recharge could be most effective.
Jan Pfeiffer et al.
Status: closed
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RC1: 'Comment on nhess-2021-388', Catherine Bertrand, 01 Mar 2022
The subject is of major interest in mountainous context where it is often difficult to make a water balance in this kind of environment. There are many reasons for this: difficulties in estimating the recharge area, difficulties in estimating the outflows, because they are frequently masked by quaternary formations or rivers. To make a water balance of an aquifer allows to better manage the water resource, which in mountainous environment is fundamental because these are often the only water resource of small communities.
This paper proposes a methodology for estimating recharge areas in particular environments that are gravity instabilities. In these environments, estimating the search area is a real issue, because it is recognized that water is an aggravating factor in the displacement of these slopes. Any identification of water inflow is therefore essential to be able to set up remediation systems (example of drainage cited by the authors).
The method developed in this study is original and seems to give promising results. Unfortunately, there are many inaccuracies in both form and substance that taint these results.
- AC1: 'Reply on RC1', J. Pfeiffer, 10 May 2022
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RC2: 'Comment on nhess-2021-388', Anonymous Referee #2, 05 Apr 2022
The article describes interesting and possibly applicable method to evaluate hydrogeological conditions governing deep seated gravitational slope deformations. I found no major drawback of the presented article, while I think the method can be quite useful even for practical landslide mitigation purposes.
- AC2: 'Reply on RC2', J. Pfeiffer, 10 May 2022
Status: closed
-
RC1: 'Comment on nhess-2021-388', Catherine Bertrand, 01 Mar 2022
The subject is of major interest in mountainous context where it is often difficult to make a water balance in this kind of environment. There are many reasons for this: difficulties in estimating the recharge area, difficulties in estimating the outflows, because they are frequently masked by quaternary formations or rivers. To make a water balance of an aquifer allows to better manage the water resource, which in mountainous environment is fundamental because these are often the only water resource of small communities.
This paper proposes a methodology for estimating recharge areas in particular environments that are gravity instabilities. In these environments, estimating the search area is a real issue, because it is recognized that water is an aggravating factor in the displacement of these slopes. Any identification of water inflow is therefore essential to be able to set up remediation systems (example of drainage cited by the authors).
The method developed in this study is original and seems to give promising results. Unfortunately, there are many inaccuracies in both form and substance that taint these results.
- AC1: 'Reply on RC1', J. Pfeiffer, 10 May 2022
-
RC2: 'Comment on nhess-2021-388', Anonymous Referee #2, 05 Apr 2022
The article describes interesting and possibly applicable method to evaluate hydrogeological conditions governing deep seated gravitational slope deformations. I found no major drawback of the presented article, while I think the method can be quite useful even for practical landslide mitigation purposes.
- AC2: 'Reply on RC2', J. Pfeiffer, 10 May 2022
Jan Pfeiffer et al.
Jan Pfeiffer et al.
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