The Contributions of MIT’s Peter S. Eagleson and the Origins of Modern Hydrologic Science

The 2023 John R. Freeman lecture will be dedicated to review and celebrate the extraordinary career and enduring legacy of Peter S. Eagleson (1928-2021). Eagleson was a professor at the Massachusetts Institute of Technology (MIT), and he is widely recognized as the father of modern hydrologic science.

Early on in his career Eagleson focused on fluid dynamics, but in the 1960’s he shifted his interest towards hydrology. Initially he worked on linear systems representations of the basin response to precipitation. By 1970 he had concluded that hydrology needed anchoring in fundamental science principles. In the groundbreaking textbook titled Dynamic Hydrology Eagleson physically and quantitatively describes the dynamics and mechanics of the hydrologic processes. This new approach coincided with the ascendance of modern computers and influenced his work on a spatially distributed, physically based, computational rainfall-runoff model called MITCAT. The descendants of that model live to this day in consulting practice.

In 1978 Eagleson published an extraordinary series of seven papers in Water Resources Research with the common title Climate Soil and Vegetation that combined physical and stochastic elements underpinning hydrologic processes. The genesis for the papers was a series of talks delivered in 1977 to BSCES as that year’s BSCES John R. Freeman Lecture. His hypothesis was the existence of a “climax,” a unique combination of the three components of the biosphere-geosphere-atmosphere system; a tendency to a long-term equilibrium everywhere over land. This concept was the beginning of a new paradigm now known as ecohydrology. Ecohydrology is an interdisciplinary field that studies the interactions between water bodies such as rivers and lakes, the vadose zone, groundwater, aquatic ecosystems such as wetlands and terrestrial ecosystems such as forests, deserts and savannahs.

After his retirement, Eagleson produced two other books, Ecohydrology: Darwinian Expression of Vegetation Form and Function (2002) and Range and Richness of Vascular Land Plants (2009) that further developed and anchored the concept of ecohydrology. 

Eagleson extended hydrology from the local into the regional and global scales.  From 1978 to 1982 he chaired the Working Group on Land Surface Processes of the Global Atmospheric Research Program (GARP), and edited the book, Land Surface Processes in Atmospheric General Circulation Models (1982). In this role he became the first hydrologist to address global-scale issues and opened a dialogue between hydrologists and atmospheric scientists. The book provided the research agenda for the first decade of study of global-scale hydrology.

He promoted and secured a study sponsored by the National Academies, and in 1991 the National Research Council published Opportunities in the Hydrologic Sciences as the book report of a committee chaired by Peter Eagleson. The so-called “Blue-Book” established the hydrologic sciences as pillars along other geosciences that collectively support our understanding of the Earth System and guide our stewardship of the home planet.  The “Blue-Book” and the efforts leading to its publication resulted in the establishment of the National Science Foundation (NSF)’s Hydrologic Sciences Program and inspired the creation of the Consortium of Universities for the Advancement of Hydrologic Science (CUAHSI). 

Other leadership roles included heading the Department of Civil and Environmental Engineering at MIT (1970-1975) and the presidency of the American Geophysical Union (AGU). BSCES peers awarded Eagleson the Desmond Fitzgerald Medal in 1959 and the Clemens Herschel Prize in 1965.  He was also awarded the Research Prize of the American Society of Civil Engineers in 1963 and was a member in good standing of ASCE for over 50 years. Eagleson was awarded the prestigious Stockholm International Water Institute World Water Prize in 1997. Other awards include the AGU’s William Bowie Medal (1994), MIT's James R. Killian Faculty Achievement Award (1992-1993), AGU’s International Hydrology Prize (1991) and AGU’s Robert E. Horton Medal (1988).