The main objective of our research is to quantify the links between the physical heterogeneity of subsurface environments, including porous and fractured media, the heterogeneity of the resulting flow fields, and the effective transport behavior, including solute dispersion, mixing, and (bio-)chemical reactions. We tackle these problems using both experiments - performed over scales ranging from micro to field scale - and (numerical and theoretical) modelling. The environmental and industrial applications of our research include the study of the impact of climate change on groundwater resources, remediation of polluted sites, nuclear waste storage, geothermal energy, geological sequestration of CO2, recovery of hydrocarbons, and hydraulic fracturing.