Research Projets

Scientific context

• Groundwater is an important part of drinking water as high as 63 % in France. It also represents 96 % of the water intake points compared to 4 % for surface water. Groundwater is highly dependent on the percentage of pores (porosity), their size and connectivity (permeability) and on the biochemical reactivity. These parameters (porosity, permeability, reactivity) are highly variable. In sedimentary structures, the deposition modes of grains induce permeability to shift over three to four orders of magnitude. In rocks, parallel fractures may represent only 0.01 % of the volume although they are the sole water carrying structures. The geological complexity addresses a challenge for the management of groundwater.
• Fractures and heterogeneous sedimentary units cannot be identified whatever the remote data. Because data give a rather scarce description of the hydraulic properties, predictions rely heavily on modelling, and particularly on numerical modelling. We underline that the physical phenomenon is not complex in itself but both the broad geological heterogeneity and the lack of observations require dealing with uncertainty. In this context, numerical modelling should integrate the multi-scale geological heterogeneity, simulate the hydraulic flow and transport phenomena and quantify uncertainty coming from the lack of data.
• Analytical techniques like homogenization or perturbations are in general not relevant. Modelling must thus be performed in a probabilistic framework that transfers the lack of data on prediction variability. In this stochastic approach, numerical simulations consist in computing the velocity field over large spatial domains and solving solute transport over large temporal scales. High performance computing is thus necessary to carry out these large scale simulations.

Research topics

• The development of the platform H2OLAB is one workpackage of the ANR project MICAS.
  Other workpackages of MICAS include numerical models for flow and transport in porous and fractured media, geophysical studies such as upscaling and macro-dispersion, uncertainty quantification, domain decomposition methods, high performance computing.
• Research projects of the different partners can be found on their respective websites.