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Université de Neuchâtel

Geological realism in hydrogeological and geophysical inverse modeling : A review

Linde, Niklas ; Renard, Philippe ; Mukerji, Tapan ; Caers, Jef

In: Advances in Water Resources, 2015, vol. 86, p. 86-101

Scientific curiosity,exploration of georesources and environmental concerns are pushing the geoscientific research community toward subsurface investigations of ever-increasing complexity.This review explores various approaches to formulate and solve inverse problems in ways that effectively integrate geological concepts with geophysical and hydrogeological data. Modern geostatistical simulation...

Université de Neuchâtel

Binary upscaling on complex heterogeneities : The role of geometry and connectivity

Oriani, Fabio ; Renard, Philippe

In: Advances in Water Resources, 2014, vol. 64, p. 47-61

The equivalent conductivity (Keq) of a binary medium is known to vary with the proportion of the two phases, but it also depends on the geometry and topology of the inclusions. In this paper, we analyze the role of connectivity and shape of the connected components through a correlation study between Keq and two topological and geometrical indicators: the Euler...

Université de Neuchâtel

Simulation of rainfall time series from different climatic regions using the direct sampling technique

Oriani, Fabio ; Straubhaar, Julien ; Renard, Philippe ; Mariethoz, Grégoire

In: Hydrology and Earth System Sciences, 2014, vol. 18, p. 3015-3031

The direct sampling technique, belonging to the family of multiple-point statistics, is proposed as a nonparametric alternative to the classical autoregressive and Markovchain-based models for daily rainfall time-series simulation. The algorithm makes use of the patterns contained inside the training image (the past rainfall record) to reproduce the complexity of the signal without inferring its...

Université de Neuchâtel

Simulation of braided river elevation model time series with multiple-point statistics

Pirot, Guillaume ; Straubhaar, Julien ; Renard, Philippe

In: Geomorphology, 2014, vol. 214, p. 148-156

A new method is proposed to generate successive topographies in a braided river system. Indeed, braided river morphologymodels are a key factor influencing river–aquifer interactions and have repercussions in ecosystems, flood risk or water management. It is essentially based on multivariate multiple-point statistics simulations and digital elevation models as training data sets. On the one...

Université de Neuchâtel

Hydraulic subsurface measurements and hydrodynamic modelling as indicators for groundwater flow systems in the Rotondo granite, Central Alps (Switzerland)

Ofterdinger, U. S ; Renard, Philippe ; Loew, S

In: Hydrological Processes, 2014, vol. 28, no. 2, p. 255-278

Regional groundwater flow in high mountainous terrain is governed by a multitude of factors such as geology, topography, recharge conditions, structural elements such as fracturation and regional fault zones as well as man-made underground structures. By means of a numerical groundwater flow model, we consider the impact of deep underground tunnels and of an idealized major fault zone on the...

Université de Neuchâtel

Prediction-Focused Subsurface Modeling: Investigating the Need for Accuracy in Flow-Based Inverse Modeling

Scheidt, Céline ; Renard, Philippe ; Caers, Jef

In: Mathematical Geosciences, 2015, vol. 47, no. 2, p. 173-191

The objective of most formulations of inverse modeling in the Earth Sciences is to estimate the model parameters given the observation data. In this paper, an additional element to these formulations is considered, namely, the prediction for which the models are built. An example of such modeling is the prediction of solute transport using geological models of the subsurface constrained to...

Université de Neuchâtel

Analog-based meandering channel simulation

Mariethoz, Gregoire ; Comunian, Alessandro ; Irarrazaval, Inigo ; Renard, Philippe

In: Water Resources Research, 2014, vol. 50, no. 2, p. 836–854

Characterizing the complex geometries and the heterogeneity of the deposits in meandering river systems is a long-standing issue for the 3-D modeling of alluvial formations. Such deposits are important sources of accessible groundwater in alluvial aquifers throughout the world and also play a major role as hydrocarbons reservoirs. In this paper, we present a method to generate meandering river...

Université de Neuchâtel

Assessing the effect of different river water level interpolation schemes on modeled groundwater residence times

Diem, Samuel ; Renard, Philippe ; Schirmer, Mario

In: Journal of Hydrology, 2014, vol. 510, p. 393-402

Obtaining a quantitative understanding of river–groundwater interactions is of high practical relevance, for instance within the context of riverbank filtration and river restoration. Modeling interactions between river and groundwater requires knowledge of the river’s spatiotemporal water level distribution. The dynamic nature of riverbed morphology in restored river reaches might result in...