Murugesu Sivapalan

2011 Robert E. Horton Medal Winner

Murugesu Sivapalan was awarded the 2011 Robert E. Horton Medal at the AGU Fall Meeting Honors Ceremony, held on 7 December 2011 in San Francisco, Calif. The medal is for “outstanding contributions to hydrology.”


It is a pleasure to introduce Murugesu Sivapalan of the University of Illinois at Urbana-Champaign as the recipient of the 2011 Robert Horton Medal.

Sivapalan is a leader in the development of hydrological theory, recognized for publishing influential papers on the fluid mechanics and thermodynamics of water movement at catchment scale, involving hydrology, geomorphology, soil science, and ecology. His pioneering efforts have been extended through sharing his expertise and interdisciplinary perspective as a leader of research groups and pathbreaking workshops. These roles have been acknowledged through his election to fellowship in the Australian Academy of Technological Sciences and Engineering and in AGU, as well as the award of the European Geophysical Society’s Dalton Medal, the International Hydrology Prize of the International Association of Hydrological Sciences, AGU’s 2010 Hydrologic Sciences Award, and the Australian government’s Centenary Medal.

A statistical accounting of Siva’s accomplishments, however, does no justice to the originality of his insights and their impact on the modernization of catchment hydrology.

Siva’s early work on the influence of scale on hydrologic prediction demonstrated that controls on water movement in landscapes have spatial and temporal structures, governed by physical principles and coevolution over various time periods. He proposed that the spatial structures and characteristic time scales of these controls could provide a basis for using general hydrological features in making predictions.

Siva pointed out that predictions of water cycle dynamics face two significant challenges. The first is that environmental change, intensified by anthropogenic influences, implies that historical records cannot be relied on for predictions of future behavior based solely on extrapolation, statistical analysis, and calibration of nominally process based models. Instead, those records, and new types of observations, must be mined for physical insights about how process dynamics and their exogenous controls generate water resources and hazards.

Siva’s second emphasis is the interaction of the hydrologic cycle with other physical, biotic, and social systems. Water is involved in everything from Earth’s mantle through its landscape formation, ­near-​­surface and surface water bodies, soil mantle, ecosystems, atmosphere, and even our minds through our desires and group actions. Each of these systems affects the availability of water and, in turn, is affected by it. And each has its own spatial and temporal characteristics of pattern formation and functioning. Understanding the evolution of these patterns and the probability distributions of their properties facilitates predicting behavior of water at catchment scales. Hydrological predictions in nonstationary watersheds must therefore be based on explicit, accurate accounting for changes in structure, drivers, and the resulting dynamics of these interacting systems through formulating physically based models within a statistical framework.

Formulation of hydrologic theory to meet these challenges is what Siva is accomplishing and promulgating. He has articulated the challenge, organized approaches for confronting it, and demonstrated how to make progress. This kind of reach across theory and empiricism and into the future of hydrology as a socially valuable Earth science makes Murugesu Sivapalan a visionary and unselfish contributor to the advancement of the field and a worthy recipient of a medal that reminds us of Robert Horton.


—Thomas Dunne, Bren School of Environmental Science and Management and Department of Earth Science, University of California, Santa Barbara


I am delighted to receive this medal, and even more so to have as citationist Tom Dunne, a hero of mine for over 25 years. At the outset I want to record my sincere thanks to many friends, led by Hubert Savenije, for nominating me for this prestigious medal.

Tom’s citation might have given you the impression that my research was somehow well scripted. Of course, it would be nice if life would be so predictable, even in hindsight. As one who hails from a land once known as Serendib, a little bit of serendipity must have rubbed off on me, so much so that my life’s trajectory has been a series of accidents or inspired choices. Each was a turning point, and yet two constants were the fire instilled in me by my parents and the support of my wife and family. Another was some key people who serendipitously came into my life: teachers who picked me out from the crowd and lifted me up, students who shared their ideas and enthusiasm, a close coterie of friends who offered both honest criticism and unqualified support, and mentors who helped me get over difficult obstacles. Driven by circumstances, I had to pursue my dream in five continents, as a veritable academic nomad, yet I am proud about how much I have gained from each place and the roots I have left behind.

I remember my Ph.D. days as a struggle, with a fear of failure that became the driving force in my later successes. I had framed my Ph.D. thesis using ideas from Jim Dooge and Vit Klemes, yet in the end I felt I did not do justice to them. In a sense, I am still working on my unfinished Ph.D. thesis. My early work was on scale issues in event runoff predictions. I then expanded it to include complete water balance modeling, which propelled me into the Predictions in Ungauged Basins initiative. Fundamental challenges posed by subsurface heterogeneity led me into the “functional” approach to modeling, opening up interdisciplinary collaborations with ecologists and pedologists. Realizing that ­human-​­induced change is even more challenging than heterogeneity, predictions under change became a new focal point of my research. Being part of the Hydrologic Synthesis Project has enabled me to work with an amazing set of colleagues and students, who have, yet again, helped to open up new horizons and expanded opportunities for research, this time based on “comparative hydrology.”

Looking back 30 years I am amazed by how much hydrology has grown and how I have grown with it. Watershed hydrology has enjoyed a great revival, with science and engineering coming together to advance the cause of predictions. Even as I receive this medal, I am delighted to be in the middle of another global initiative, this time on predictions under change, putting humans squarely in the middle of the landscapes we study. For me it has been an incredible journey. Along the way, I have been grateful, indeed blessed, to work with and learn from numerous teachers, colleagues, and students, some of whom are here in this audience. I am grateful to AGU for tonight’s honor, and I thank you all for honoring me through your presence.

Good evening.

—Murugesu Sivapalan, University of Illinois at Urbana-Champaign