Université de Neuchâtel

Conditioning groundwater flow parameters with iterative ensemble smoothers : analysis and approaches in the continuous and the discrete cases

Lam, Dan-Thuy ; Renard, Philippe (Dir.) ; Kerrou, Jaouher (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2019.

Data assimilation (DA) consists in combining observations and predictions of a numerical model to produce an optimal estimate of the evolving state of a system. Over the last decade, DA methods based on the Ensemble Kalman Filter (EnKF) have been particularly explored in various geoscience fields for inverse modelling. Although this type of ensemble methods can handle high-dimensional systems,...

Université de Neuchâtel

Process based modeling of the karstification processes in the region of Tulum, Mexico

Maqueda, Axayacatl ; Renard, Philippe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2017.

Caves are important since they are preferential paths for groundwater flow. Knowledge of caves or karst is essential for proper management of water resources, but the exploration of caves is a major challenge. An alternative to study caves and their structure is to simulate the processes related to cave growth. The motivation of this thesis is to study large karst networks in the region of...

Université de Neuchâtel

Connectivity of channelized sedimentary bodies : analysis and simulation strategies in subsurface modeling = Connectivité de corps sédimentaires chenalisés : stratégies d'analyse et de simulation en modélisation de subsurface

Rongier, Guillaume ; Renard, Philippe (Dir.) ; Sausse, Judith (Dir.) ; Collon, Pauline (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2016.

Channels are the main sedimentary structures for sediment transportation and deposition from the continents to the ocean floor. The significant permeability of their deposits enables fluid circulation and storage. As illustrated with turbiditic systems, those channel fill is highly heterogeneous. Combined with the spatial organization of the channels, this impacts significantly the connectivity...

Université de Neuchâtel

Stochastic simulation of rainfall and climate variables using the direct sampling technique

Oriani, Fabio ; Renard, Philippe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2015.

An accurate statistical representation of hydrological processes is of paramount importance to evaluate the uncertainty of the present scenario and make reliable predictions in a changing climate. A wealth of historic data has been made available in the last decades, including a consistent amount of remote sensing imagery describing the spatio-temporal nature of climatic and hydrological...

Université de Neuchâtel

Scaling behaviours of karst networks around Tulum (Mexico) : characterization, model and application

Hendrick, Martin ; Renard, Philippe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2016.

An unsolved problem in the field of karst networks is to understand and describe their large scale behaviours. The characterization of the structure of karst systems is crucial for many practical purposes, as for example, ground surface stability assessment and water resource management. However, there is no general framework that allows to fully characterize and model a network. Natural...

Université de Neuchâtel

Gravimetry for geothermal exploration : methodology, computer programs and two case studies in the Swiss Molasse basin

Altwegg, Pierrick ; Renard, Philippe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2015.

In Switzerland and neighboring countries, most deep geothermal projects target deep aquifers associated with major fault zones. The objective of this thesis is to develop and test a methodology for the estimation and localization of such high porosity rock volumes in the underground using gravity data and 3D geological modeling. To reach that aim, the computer program GInGER – GravImetry...

Université de Neuchâtel

Stochastic heterogeneity modeling of braided river aquifers : a methodology based on multiple point statistics and analog data

Pirot, Guillaume ; Renard, Philippe (Dir.) ; Straubhaar, Julien (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2015.

In this thesis a new pseudo-genetic method to model the heterogeneity of sandy gravel braided-river aquifers is proposed. It is tested and compared with other modeling approaches on a case study of contaminant transport. Indeed, in Switzerland or in mountainous regions, braided-river aquifers represent an important water resource that need to be preserved. In order to manage this resource, a good...

Université de Neuchâtel

Inverse modeling of groundwater flow in the Rhône alluvial aquifer - impact of the Third Rhône correction

Glenz, Damian ; Renard, Philippe (Dir.) ; Perrochet, Pierre (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2013.

The main objective of this thesis is the quantitative evaluation of the impact of the Third Rhône correction (PR3) on groundwater within the Rhône alluvial aquifer. PR3 is a river restoration project which aims at improving flood protection and at upgrading the ecologically deficient streambed of the Rhône River (Valais, Switzerland). The approach taken to extend the drainage capacity of the...

Université de Neuchâtel

3D stochastic modeling of karst aquifers using a pseudo-genetic methodology

Borghi, Andrea ; Renard, Philippe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2013.

The focus of this thesis is the development of a methodology to model karst aquifers. First the geometry of the karst conduits is simulated. Their geometry is controlled by the geology at large scale (geological model) and by the fracturation at smaller scale (stochastic model of fractures). Secondly, these geometrical models (3D geological formation together with conduits) are used as base...

Université de Neuchâtel

Probability aggregaton methods and multiple-point statistics for 3D modeling of aquifer heterogeneity from 2D training images

Comunian, Alessandro ; Renard, Philippe (Dir.) ; Straubhaar, Julien (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2011 ; 2187.

Multiple-point statistics (MPS) is a rising method for the characterization of heterogeneity. Its strength and its Achilles' heel lie in the training image, which is the conceptual model of geological heterogeneity on which MPS simulations are based. Indeed, on one side the use of the training image allows great flexibility when for example for bi-dimensional (2D) simulation a training image can...