Upmanu Lall

The 2014 Henry Darcy Medal is awarded to Upmanu Lall for incisive contributions to the understanding and predictability of regional and global hydrologic processes under global change and for contributions to solving the global water crisis.

Upmanu Lall was among the first to recognise the importance of climate tele-connections as drivers for terrestrial hydrology, and one of the few who has tackled the problem of how flood risk may change with changing climate, with a sharp focus on underlying climate mechanisms. He has taken on the challenge of finding solutions to the growing water crisis in developing countries, including India, China and Brazil, under the threat of climate change and growth of human populations. Lall has relentlessly pursued corporate support for this work and was successful in establishing the Columbia Water Center with funding from private and public foundations. The resulting substantial body of his work has had a huge impact, helping to revitalise stochastic hydrology at a time when this important field was in its mature phase.

Lall received his training in the 1970s and early 1980s when systems analysis was a watchword in hydrology and water resources. Lall realised, however, that hydrologic systems analysis, as practiced then, prescribed narrow boundaries on the systems being studied. Data was a vehicle for parameter estimation and model calibration, rather than being the basis for the exploration of pattern, structure and function. These insights led him into his main forte of nonparametric function estimation, the best exposition of which is his 1995 Reviews of Geophysics paper, where he narrates the history of ideas that led to the renaissance of nonparametric methods. This work also led Lall to the question of hydrologic predictability, of which he is the foremost authority amongst current leaders. His work on the strengths and limitations of spatially explicit models of global and regional climate helped to focus his interest in seasonal to millennial scale dynamics of hydro-climatic systems. It is Lall’s work in the last decade that may turn out to be the most significant. The maturing of his ideas on global change led to his articulation of hydromorphology, the study of long term evolution of hydrologic systems, with climate and human activity as integral, interactive components, of which theme Lall is the intellectual leader.

Benefiting from insights far ahead of his time, Lall has had a profound impact on the direction and practice of scientific hydrology and water resources systems analysis. The time, effort and emotional engagement that Lall is contributing to address a problem that impacts hundreds of millions of people by blending scientific and technological insights with societal inputs is remarkable for a top-notch academician.