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Université de Neuchâtel

A pseudo genetic model of coarse braided-river deposits

Pirot, Guillaume ; Straubhaar, J ; Renard, Philippe

In: Water Resources Research, 2015, vol. 51, no. 12, p. 9595-9611

A new method is proposed to produce three-dimensional facies models of braided-river aquifers based on analog data. The algorithm consists of two steps. The first step involves building the main geological units. The production of the principal inner structures of the aquifer is achieved by stacking Multiple-Point-Statistics simulations of successive topographies, thus mimicking the major...

Université de Neuchâtel

Influence of conceptual model uncertainty on contaminant transport forecasting in braided river aquifers

Pirot, Guillaume ; Renard, Philippe ; Huber, E ; Straubhaar, J ; Huggenberger, P

In: Journal of Hydrology, 2015, vol. 531, p. 124-141

Hydrogeologist are commonly confronted to field data scarcity. An interesting way to compensate this data paucity, is to use analog data. Then the questions of prediction accuracy and uncertainty assessment when using analog data shall be raised. These questions are investigated in the current paper in the case of contaminant transport forecasting in braided river aquifers. In using analog data...

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

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

Distance-based kriging relying on proxy simulations for inverse conditioning

Ginsbourger, David ; Rosspopoff, Bastien ; Pirot, Guillaume ; Durrande, Nicolas ; Renard, Philippe

In: Advances in Water Resources, 2013, vol. 52, p. 275–291

Let us consider a large set of candidate parameter fields, such as hydraulic conductivity maps, on which we can run an accurate forward flow and transport simulation. We address the issue of rapidly identifying a subset of candidates whose response best match a reference response curve. In order to keep the number of calls to the accurate flow simulator computationally tractable, a recent...

Université de Neuchâtel

A practical guide to performing multiple-point statistical simulations with the Direct Sampling algorithm

Meerschman, Eef ; Pirot, Guillaume ; Mariethoz, Gregoire ; Straubhaar, Julien ; Van Meirvenne, Marc ; Renard, Philippe

In: Computers & Geosciences, 2013, vol. 52, p. 307-324

The Direct Sampling (DS) algorithm is a recently developed multiple-point statistical simulation technique. It directly scans the training image (TI) for a given data event instead of storing the training probability values in a catalogue prior to simulation. By using distances between the given data events and the TI patterns, DS allows to simulate categorical, continuous and multivariate...