JC Maréchal is a senior hydrogeologist specialized in the study of fractured and karst environments. He has worked on the development of methodologies for the assessment of groundwater resources in crystalline rock aquifers using multidisciplinary approaches aimed at the characterization of the structure and functioning at the watershed scale, the estimation of natural recharge, the budget of aquifers in semi-arid environments, the hydrodynamic modelling of crystalline rock aquifers and the implementation and interpretation of pumping tests, in the framework of research projects. 
He was co-chairman of the French-Indian Groundwater Research Center between 2000 and 2003. He is in charge of the Hyderabad Research Observatory, associated with SOERE H+ and IR OZCAR. 
He has also developed methods for interpretation and modeling of pumping tests in karst conduits. He has participated in and coordinated numerous national and international research projects on the topics of managed aquifer recharge, karst hydrogeology and management of mineral water reservoirs.
Since 2011, he has been Head of the New Water Resource and Economy Unit of the Water Division at BRGM. He is also Deputy Director of G-eau Research Unit.