Vignette d'image

Schilling, Oliver

Nom
Schilling, Oliver
Affiliation principale
Identifiants
https://libra.unine.ch/handle/123456789/807

Résultat de la recherche

Filtres

42
4
31
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 4 sur 4
  • Publication
    Accès libre
    A Framework for Untangling Transient Groundwater Mixing and Travel Times
    (2021-2)
    Popp, Andrea L.
    ;
    Pardo-Alvarez, Alvaro
    ;
    Schilling, Oliver 
    ;
    Scheidegger, Andreas
    ;
    Musy, Stephanie
    ;
    Peel, Morgan 
    ;
    Brunner, Philip 
    ;
    Purtschert, Roland
    ;
    Hunkeler, Daniel 
    ;
    Kipfer, Rolf
    Understanding the mixing between surface water and groundwater as well as groundwater travel times in vulnerable aquifers is crucial to sustaining a safe water supply. Age dating tracers used to infer apparent travel times typically refer to the entire groundwater sample. A groundwater sample, however, consists of a mixture of waters with a distribution of travel times. Age dating tracers only reflect the proportion of the water that is under the dating range of the used tracer, thus their interpretation is typically biased. Additionally, end-member mixing models are subject to various sources of uncertainties, which are typically neglected. In this study, we introduce a new framework that untangles groundwater mixing ratios and travel times using a novel combination of in-situ noble gas analyses. We applied this approach during a groundwater pumping test carried out in a pre-alpine Swiss valley. First, we calculated transient mixing ratios between recently infiltrated river water and regional groundwater present in a wellfield, using helium-4 concentrations combined with a Bayesian end-member mixing model. Having identified the groundwater fraction of recently infiltrated river water (Frw) consequently allowed us to infer the travel times from the river to the wellfield, estimated based on radon-222 activities of Frw. Furthermore, we compared tracer-based estimates of Frw with results from a calibrated numerical model. We demonstrate (i) that partitioning of major water sources enables a meaningful interpretation of an age dating tracer of the water fraction of interest and (ii) that the streambed has a major control on the estimated travel times.
  • Publication
    Accès libre
    Advancing Physically-Based Flow Simulations of Alluvial Systems Through Atmospheric Noble Gases and the Novel 37Ar Tracer Method
    (2017-12-26)
    Schilling, Oliver 
    ;
    Gerber, Christoph
    ;
    Purtschert, Roland
    ;
    Brennwald, Matthias S.
    ;
    Kipfer, Rolf
    ;
    Hunkeler, Daniel 
    To provide a sound understanding of the sources, pathways, and residence times of groundwater water in alluvial river-aquifer systems, a combined multitracer and modeling experiment was carried out in an important alluvial drinking water wellfield in Switzerland. 222Rn, 3H/3He, atmospheric noble gases, and the novel 37Ar-method were used to quantify residence times and mixing ratios of water from different sources. With a half-life of 35.1 days, 37Ar allowed to successfully close a critical observational time gap between 222Rn and 3H/3He for residence times of weeks to months. Covering the entire range of residence times of groundwater in alluvial systems revealed that, to quantify the fractions of water from different sources in such systems, atmospheric noble gases and helium isotopes are tracers suited for end-member mixing analysis. A comparison between the tracer-based mixing ratios and mixing ratios simulated with a fully-integrated, physically-based flow model showed that models, which are only calibrated against hydraulic heads, cannot reliably reproduce mixing ratios or residence times of alluvial river-aquifer systems. However, the tracer-based mixing ratios allowed the identification of an appropriate flow model parametrization. Consequently, for alluvial systems, we recommend the combination of multitracer studies that cover all relevant residence times with fully-coupled, physically-based flow modeling to better characterize the complex interactions of river-aquifer systems.
  • Publication
    Accès libre
    Integrating hydrological modelling, data assimilation and cloud computing for real-time management of water resources
    (2017-7-1)
    Kropf, Peter 
    ;
    Kurtz, Wolfgang
    ;
    Lapin, Andrei 
    ;
    Tang, Qi 
    ;
    Schilling, Oliver 
    ;
    Schiller, Eryk 
    ;
    Braun, Torsten
    ;
    Hunkeler, Daniel 
    ;
    Vereecken, Harry
    ;
    Sudicky, Edward
    ;
    Franssen, Harrie-Jan Hendricks
    ;
    Brunner, Philip 
    Online data acquisition, data assimilation and integrated hydrological modelling have become more and more important in hydrological science. In this study, we explore cloud computing for integrating field data acquisition and stochastic, physically-based hydrological modelling in a data assimilation and optimisation framework as a service to water resources management. For this purpose, we developed an ensemble Kalman filter-based data assimilation system for the fully-coupled, physically-based hydrological model HydroGeoSphere, which is able to run in a cloud computing environment. A synthetic data assimilation experiment based on the widely used tilted V-catchment problem showed that the computational overhead for the application of the data assimilation platform in a cloud computing environment is minimal, which makes it well-suited for practical water management problems. Advantages of the cloud-based implementation comprise the independence from computational infrastructure and the straightforward integration of cloud-based observation databases with the modelling and data assimilation platform.
  • Publication
    Accès libre
    Wireless Mesh Networks and Cloud Computing for Real Time Environmental Simulations
    (: Springer, 2014-4-22)
    Kropf, Peter 
    ;
    Schiller, Eryk 
    ;
    Brunner, Philip 
    ;
    Schilling, Oliver 
    ;
    Hunkeler, Daniel 
    ;
    Lapin, Andrei 
    Predicting the influence of drinking water pumping on stream and groundwater levels is essential for sustainable water management. Given the highly dynamic nature of such systems any quantitative analysis must be based on robust and reliable modeling and simulation approaches. The paper presents a wireless mesh-network framework for environmental real time monitoring integrated with a cloud computing environment to execute the hydrogeological simulation model. The simulation results can then be used to sustainably control the pumping stations. The use case of the Emmental catchment and pumping location illustrates the feasibility and effectiveness of our approach even in harsh environmental conditions.