Prior uncertainty investigation of density-viscosity dependent joint transport of heat and solute in alluvial sediments

Joint heat and solute tracer tests allow to add diffusion and conduction information to the solute advection-dispersion and help imaging preferential pathways in heterogeneous aquifers. We perform a joint interpretation of heat and solute tracer tests combining deterministic modeling and Bayesian Evidential Learning. The results show a strong influence of the water viscosity. The stochastic simulations highlight the influence of spatial and parameter uncertainty on the resulting breakthrough curves, stressing the need for realistic uncertainty quantification.Joint heat and solute tracer test inversion for imaging preferential pathway

Modeling groundwater with ocean and river interaction

We develop and implement the groundwater model, Saturated/Unsaturated Flow and Transport in 3D (SUFT3D), to integrate water quantity/quality data and simulations with models of other hydrologic cycle components, namely, rivers and the ocean. This work was done as part of the Sea Air Land Modeling Operational Network (SALMON) project supported by the IBM International Foundation through its Environmental Research Program. The first research steps, presented here, address the simulation of typical hydrologic conditions to demonstrate SUFT3D's effectiveness and accuracy. The theory behind the modeling of seawater intrusion and groundwater-river interaction is summarized along with the numerical methods and characteristics of SUFT3D. The code was applied to different, increasingly complex scenarios: confined to unconfined conditions, local to regional scale, homogeneous to increasing heterogeneity, two- to three-dimensional. Of particular interest were the impacts of different boundary conditions and influence of river interactions on seawater intrusion. Results are illustrated, discussed, and compared, when possible, to those in the literature. Simulating groundwater exchange between both the river and the ocean has provided interesting results that better depict the dynamics of flow and transport in coastal zone groundwater systems

Groundwater modeling: flow simulations

The first part of the slide show consists of reminders about the basic concepts and equations of saturated groundwater flow in steady-state and transient conditions. Then, the boundary conditions (BCs) are discussed and the different possibilities are illustrated. The most common numerical techniques used to solve groundwater flow are the Finite Difference, Here, the Finite Difference method is presented in detail and on simple conceptual cases in order to keep the mathematical description relatively simple. Explicit, implicit, Crank-Nicolson and Galerkin time integration schemes are described. Useful recommendations are given for the practitioner in terms of spatial and temporal discretization and other conceptual choices. The Finite Element and Finite Volume methods are summarized in a few final slides. The following long list of references is provided in order to allow the student/researcher to go into more detail on the subject. The references are used and accordingly cited in the associated slide show. Specifically for BCs discussion, a list of provided references from the author and his research team allows finding practical examples of BCs choices in various practical cases

Groundwater modeling: solute transport simulation

The first part of the slide show consists of reminders about the basic concepts and equations of saturated solute transport processes. Then, the boundary conditions (BCs) are discussed and the different possibilities are illustrated. The most common numerical techniques used to solve solute transport are described based on the Finite Difference method. Particular attention is given to advection-dominated problems, as this is the case mostly in aquifers. Specific methods are described, such as Eulerian or grid-based methods with upwind or upstream weighting, TVD methods, Eulerian-Lagrangian methods combining a method of characteristics with traditional FD or FE methods. Peclet and Courant numerical dimensionless numbers help the user to detect the actual numerical conditions, adapt time steps, and to choose which specific method should be adopted. Multi-species reactive transport is a coupled problem that can be simulated sequentially or in parallel. The following long list of references is provided in order to allow the student/researcher to go into more detail on the subject. The references are used and accordingly cited in the associated slide show. Specifically for BCs discussion, a list of provided references from the author and his research team allows finding practical examples of BCs choices in various practical cases

Migration of contaminants through the unsaturated zone overlying the Hesbaye chalky aquifer in Belgium: a field investigation

peer reviewedThis paper presents the results of a detailed field investigation that was performed for studying groundwater recharge processes and solute downward migration mechanisms prevailing in the unsaturated zone overlying a chalk aquifer in Belgium. Various laboratory measurements were performed on core samples collected during the drilling of boreholes in the experimental site. In the field, experiments consisted of well logging, infiltration tests in the unsaturated zone, pumping tests in the saturated zone and tracer tests in both the saturated and unsaturated zones. Results show that gravitational flows govern groundwater recharge and solute migration mechanisms in the unsaturated zone. In the variably saturated chalk, the migration and retardation of solutes is strongly influenced by recharge conditions. Under intense injection conditions, solutes migrate at high speed along the partially saturated fissures, downward to the saturated zone. At the same time, they are temporarily retarded in the almost immobile water located in the chalk matrix. Under normal recharge conditions, fissures are inactive and solutes migrate slowly through the chalk matrix. Results also show that concentration dynamics in the saturated zone are related to fluctuations of groundwater levels in the aquifer. A conceptual model is proposed to explain the hydrodispersive behaviour of the variably saturated chalk. Finally, the vulnerability of the chalk to contamination issues occurring at the land surface is discussed. (C) 2003 Elsevier B.V. All rights reserved.Etude phénoménologique de la propagation d'une susbtance miscible en milieu non saturé et application au transfert des nitrates vers la nappe aquifère de Hesbay

Groundwater modeling: methodological and conceptual choices

A complete methodology for groundwater flow and solute transport modeling is described step by step. Definitions, terminology, and a general methodology are proposed. Emphasis is given to the conceptual model choices involving processes to be simulated, parsimony versus complexity, and dimensionality. Model design and data input are addressed with a description of the different input data. Calibration, validation, sensitivity analysis, and inverse modeling are summarized

Modelling groundwater pumping and coupled heat transport in a alluvial aquifer: tests using different codes an optimisation

peer reviewedVarious aquifers are studied in terms of low temperature geothermal potential. The feasibility and impact studies of these systems imply very often a numerical simulation of groundwater flow and heat transport. Nowadays, some finite element or finite difference codes are able to deal with such non linear simulations. On a synthetic case study and then on a real case study, a detailed comparative sensitivity analysis is performed using three different codes (MT3DMS, SHEMAT and HYDROGEOSHERE). For low temperatures and relatively small temperature changes, it appears rapidly that the uncertainty affecting values of the main hydrodynamic parameters (i.e. hydraulic conductivity) influences more the results than taking into account any coupling or non linearity. For a case study, the pumping and associated groundwater flow and heat transport are modeled in an alluvial aquifer interacting with a main river in order to assess feasibility of a low energy air cooling /heating system for a large office building. The worst case scenario corresponds to hot summer conditions simultaneously with river maximum temperature and the model leads to an optimization with intermittent pumping in minimum 6 wells. Numerical codes are ready to simulate complex groundwater flow, solute transport and heat transport situations in aquifers, however efforts must be realized to obtain reliable experimental in-situ measured values for the hydro-thermal properties

Caractérisation hydrogéologique et support à la mise en oeuvre de la Directive Européenne 2000/60 sur les masses d’eau souterraine en Région Wallonne - Délivrable 6.0 - Note méthodologique relative à la modélisation hydrogéologique des masses d'eau souterraine RWM011, RWM012 et RWM021 (aspects quantitatifs et qualitatifs)

Synclin'Eau : Caractérisation hydrogéologique et support à la mise en oeuvre de la Directive Européenne 2000/60 sur les masses d’eau souterraine en Région Wallonn