Ghislain de Marsily: An Appreciation

Professor Ghislain de Marsily was born on October 18, 1939 in Mas d'Auge, Provence and died in Paris, France on April 21, 2024. de Marsily was an internationally renowned groundwater scholar. His teaching and research were characterized by the application of geology, engineering, mathematics, and curiosity to understanding the movement of groundwater. de Marsily made seminal contributions to the field of stochastic hydrogeology and was famed for his work as a prominent and persuasive advocate for holistic, equitable, and science-driven water management.

de Marsily graduated in 1963 as a civil mining engineer from the Ecole des Mines, Paris. A period with a public works company followed, as did an additional qualification as a geological engineer (1967). He joined academia to pursue what would be a life-long relationship with research. His first internationally significant paper, “An automatic solution for the inverse problem,” was published in Water Resources Research in 1971 (Emsellem and de Marsily 1971). Professional recognition and leadership roles followed quickly. In 1973, he was appointed to the role of Director of the Centre d'Informatique Géologique at the Ecole des Mines, and during his tenure in this position completed his PhD at the Université de Pierre and Marie Curie (also known as Paris VI) in 1978.

In 1985, de Marsily was appointed to the position of Professor of Geology at Paris VI. This heralded a new era of appointments to a variety of governance and management positions that combined his love of research with his skills as a broad thinker and communicator. These appointments included directorship of the Applied Geology Laboratory (1987-2004), foundation director of UMR CNRS SISYPHE (1989-2000) and director of the Geosciences and Natural Resources Doctoral School (2000-2004).

Professor de Marsily's teaching and research spanned hydrogeology, watershed management, sedimentary basin modeling, fractured rock hydrology, transport of heat and contaminants in porous/fractured media, and waste disposal. His works on inverse methods and stochastic hydrogeology were pioneering and have gone on to shape the discipline of environmental modeling well beyond a tool restricted to hydrogeology. His work continues to reverberate today. His 1980 paper with Georges Matheron “Is transport in porous media always diffusive? A counterexample” remains one of the most highly cited papers in hydrogeology (Matheron and de Marsily 1980). The field of geostatistics was greatly enriched by de Marsily's conceptual innovation and mathematical precision.

de Marsily was a pioneer of the now widely applied pilot point method for computer-assisted calibration of groundwater models. Without attempting to be comprehensive, readers are directed to the landmark papers of Certes and de Marsily (1991), RamaRao et al. (1995), and Lavenue and de Marsily (2001). Some easier reading is presented in a thoughtful comment on philosophical aspects of model validation (de Marsily et al. 1992).

de Marsily's commitment to communicating a sound understanding of groundwater to students across a spectrum of engineering, science and mathematics backgrounds is seen nowhere more clearly than in his textbook Hydrogéologie Quantitative (de Marsily 1981). de Marsily's wife, Gunilla, expertly translated this excellent textbook and it was published in English in 1986 as Quantitative Hydrogeology (de Marsily 1986). One of the many noteworthy aspects of the book is its elegant treatment of the integrated finite-difference method, more than 30 years ahead of the implementation of unstructured grid capabilities in MODFLOW.

de Marsily was a pillar in the academic community. He was elected to the French Academy of Sciences in 1997 and appointed to its Sciences of the Universe section in 2003, elected an international member of the US National Academy of Engineering (1999), and Fellow of the American Geophysical Union (1989). His honors include the Prix Roubault de l'Union Française des Géologues (2000) and Prix de l'IFP de l'Académie des Sciences (2001), the O.E. Meinzer Award of the Geological Society of America (2004), the Robert E. Horton Award of the American Geophysical Union (1995), the Presidents' Award from the International Association of Hydrogeologists (IAH) (2010), and the Castany's Award from the IAH French Chapter. He is the recipient of honorary doctorates from universities in Canada, Switzerland and Australia, a foundation fellow of the French Academy of Technology and worked often with the United Nations.

de Marsily's impact was significant and sustained. He traveled throughout the world lecturing and spending time with colleagues at numerous universities. He spoke widely—and published broadly—on the urgent need to understand water resources and control their exploitation to ensure an equitable and liveable planet. Climate change, population growth, and increasing resource contamination have only heightened the significance of de Marsily's message. de Marsily resisted the temptation to become completely theoretical in his outlook, always seeking the application of his methods. This grounded perspective led him to work on water quality problems with industry partners and assisting governments, community, and advocacy groups on issues such as the environmental impact of the proposed airport at Notre Dame des Landes to ensure they had access to the best science upon which to base their judgments. de Marsily believed science should be available, up to date and relevant, and he led by example. He was particularly proud of his popular book L'Eau (de Marsily, 1995) that explained basic concepts of hydrology and water for society. In this book, he discussed the hydrologic cycle and how this perpetual cycle maintains a precious ecosystem. He showed that the development of water to meet our needs can significantly modify this natural pattern.

de Marsily's scientific contributions informed public debates on nuclear waste disposal and continues to help understand the movement of contaminants and other solutes in a variety of groundwater environments. de Marsily's ideas—such as hydrogeological national parks, productive use of predictive models and the importance of sharing scientific data and access to resources in an equitable way—are concepts that continue to resonate today. For this and other services to France, academia, and science Ghislain received numerous national distinctions, including Chevalier de la Légion d'honneur, Chevalier de l'Ordre national du Mérite, Chevalier des Palmes académiques and Chevalier du Mérite Agricole. The diversity of the recognition he received serves to demonstrate the breadth of his interests, the extraordinary impact of his work and the depth of his commitment to making the world a better place.

de Marsily's legacy is one of technical mastery combined with intellectual curiosity and absolute integrity. Never one to shy away from topical, controversial, or contentious issues, Ghislain was often called upon by the French Government, the Organisation for Economic Co-operation and Development (OECD), the United Nations and numerous international agencies for assistance and advice. Ghislain served as a member of the International Atomic Energy Agency (IAEA) review team of the Mururoa-Fangataufa French nuclear tests in the mid- to late-1990s. For the French Government he provided advice regarding the storage of industrial waste in Montchanin and spent over a decade serving on the legally mandated governance commission overseeing the disposal of radioactive waste. Ghislain worked with international energy agencies and the OECD to explore seabed storage of radioactive material.

Ghislain de Marsily was a true gentleman scientist with a vast global network of collaborators, colleagues, and friends, a testament to his positive spirit and willingness not only to teach, but to learn from those who shared his enthusiasm and diverse interests. Many of his students found employment as academics or engineers and it is through them that his passion for communication, intellectual pursuits and academic rigor lives on. He is survived by his wife of over 60 years, Gunilla, three children and five grandchildren.

Links to additional documentation of de Marsily's career and publications are presented in the Further information at the end of this article.