ESR N°1 : Mixing and chemical reaction hotspots in saline-freshwater mixing zones

Research Fellow: Kevin De Vriendt

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Host Institution: Spanish National Research Council
(CSIC), Barcelona

Objectives: The main objectives are to identify and quantify the structural and hydraulic controls of mixing and evaluate the influence of fluctuations in recharge and temperature. The idea is that fluid deformation in heterogeneous media together with local dispersion lead to a strong localization of enhanced mixing and reaction efficiency, which is amplified by density variations. Numerical simulations of variable density flow in heterogeneous aquifer coupled to geochemical reactions will give new insight into these processes, which will be contrasted to data from geophysical monitoring and experimentation.

Collaboration on the development and use of novel techniques for the characterization of transport and flow heterogeneity as well as reaction monitoring will be done with ESRs 9 and 12.

More details about ESR1-project:


  • CNRS: 5 months September-December 2019
  • UNIL: 4 months feb 2020
  • ACA: 1 month August 2020

Tasks and methodology:

  • Quantification of flow heterogeneity and fluid deformation
  • Identification of flow strain and stress centers, which drive concentration gradients and mixing,
  • The development of mixing and reaction diagnostics to explain and predict observed reaction patterns.

Project description:

Mixing across the SW-FW (saltwater-freshwater) interface is a key process that affects karst development, exchange reactions and biochemical processes. The evolution of the SW-FW interface is strongly influenced by the density difference between salt and freshwater as well as temporal flow fluctuations induced for example by sea level fluctuations, and ever present spatial heterogeneity in the hydraulic and chemical medium properties. The mixing processes across the interface may furthermore be affected by inland recharge and temperature variations. Monitoring these influences, coupled with field experiments and numerical modeling, will hopefully provide new insights into mixing and freshwater displacement in coastal aquifers and subsequent geochemical reactions.


Marco Dentz – Spanish National Research Council (CSIC)
Maria Pool – Spanish National Research Council (CSIC)

Dissemination and communications

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Database for the future datasets : H+ database

Next page : See ESR2 – project