# Rodriguez-Iturbe, Ignacio

## Contents

## Photograph

## Dates

Ignacio Rodriguez-Iturbe. 8 March 1942 (Maracaibo, Venezuela) – 27 October 2022 (Caracas, Venezuela)

## Biography

Ignacio Rodríguez-Iturbe was born in Maracaibo, Venezuela on March 8, 1942. He was educated in the Universidad del Zulia in Maracaibo, where his father was Dean of the Faculty of Engineering). He received a C.E. with maximum honors in 1963. He received a MS at the California Institute of Technology in 1965 and a Ph.D. from Colorado State University in 1967 under the supervision of Vijuca Yevjevich. He later worked at the University of Zulia, the Massachusetts Institute of Technology in Cambridge, the Universidad Simon Bolivar in Caracas, the University of Iowa in Iowa City, Texas A&M at College Station, and for twenty years Princeton University, where he was the James S. McDonnell Distinguished University Professor of Civil and Environmental Engineering. He also held various appointments as visiting Professor in several countries.

Ignacio was a Member or Fellow of multiple international honorary societies, including the U.S. National Academy of Sciences and National Academy of Engineering; the American Academy of Arts and Sciences; the Istituto Veneto di Scienze, Lettere ed Arti; the Pontifical Academy of Sciences and the Third World Academy of Sciences. He received honorary degrees, among which those that were dearest to him included one from the University of Zulia in Maracaibo, where he had obtained his CE; the degree in Environmental Engineering from the University of Genoa on the occasion of the Colombian celebrations; and an honorary Ph.D. from the University of Cantabria.

In 1964, he married Mercedes Maiz, who gave him Oscar, Ignacio, Olimpia, Juan, and Luis. Ignacio and Mercedes had only recently returned to Venezuela after his retirement from Texas A&M.

## Hydrological Achievements

Ignacio was a towering scientific and academic figure in the field of hydrology. His early research focused on the analysis, synthesis, and sampling of hydrological processes, focusing in particular on the stochastic characters of rainfall events and those of their measurement networks. His contributions were remarkable for the extraordinary mathematical which allowed him to publish a series of fundamental papers jointly with leading hydrologists and statisticians.

In the late 1970s, Ignacio turned his interests toward the connection of geomorphology and hydrology, and in particular on the role of form and function of river networks. In those years, he pioneered the so-called geomorphological theory of the hydrological response, which radically changed the empirical approaches used by engineers for more than a century to predict floods. Later, he concentrated on the origins, the dynamics, and the stationary states of the geomorphology of natural river networks in runoff-producing areas. In the early 90s, he was the leading force behind the development of the theory of optimal channel networks, a significant step forward in our understanding of how nature works within the larger debate on the dynamic origins of scale-invariant natural forms or, the dynamic origins of the fractal geometry of nature. In parallel, Ignacio contributed essentially to the gathering of key field evidence on the form of river networks, using the then cutting-edge technology of remotely acquired and objectively manipulated information of digital terrain maps and the extraction of properly channelized landforms.

The proof of the scale-invariance of the master variables of river network hydrology over up to six orders of magnitude, from the scale of 1 meter to thousands of kilometres, placed hydrology and geomorphology firmly within a larger stage, that of the physics of fractal. Overall, the development and the validation of the theory of optimal channel networks represented a major step forward that revolutionized our understanding of the form and function of river networks and of the dynamic origins of fractal geometries in nature.

Toward the turn of the century, Ignacio jump-started the study of the probabilistic structure of the interactions among climate, soil, and vegetation. In the process, he became the main architect of the birth and the subsequent establishment of a new discipline, Ecohydrology, which is now established as the science that has revolutionized the study and the management of ecosystems through the probabilistic characterization of natural forcings linked to the waters of the hydrological cycle.

Ignacio’s last decade was devoted mainly to studies in water controls of the distribution of species, populations, and pathogens in natural ecosystems, and in particular to river networks seen as ecological corridors. He also made important contributions to studies on large-scale soil moisture dynamics, theoretical work on evapotranspiration patterns due to spatial heterogeneity of plant species, and the study of virtual water trade networks, whose understanding is crucial toward a rigorous definition of a fair distribution of water.

Ignacio Rodríguez-Iturbe was the recipient of an extraordinary number of awards and prizes for his research work, a testament to his exceptional academic standards. Among these, the 2002 Stockholm Water Prize stands out, as it is universally recognized as the Nobel Prize for water studies. Among others, it seems worth mentioning the Prince Sultan Bin Abdulaziz International Water Prize (for creativity) in 2010, and the awards bestowed on him by the American Geophysical Union, including the Macelwane, the Horton, and the Bowie Medals, covering the whole spectrum of geophysics and recognition of unselfish cooperation in science.

Significantly, there exist already two Ignacio Rodriguez-Iturbe Awards: one for outstanding scientific achievements in any field of science given by his Alma Mater, Universidad del Zulia; and the other for the best article published each year in the international journal Ecohydrology.

## Anecdotes

Ignacio recalled that the fundamental unity of the seemingly disparate problems of water-controlled population ecology, waterborne disease spread, and biological invasions in fluvial systems was cast in a final form during a walk around the pond of the Institute for Advanced Studies in Princeton, in the best tradition of the peripatetic philosophers.

## Reference Material

The text in this entry is modified from the article by Simon A. Levin, and Andrea Rinaoldo, Ignacio Rodríguez-Iturbe (1942–2022): A review of a pathbreaking academic career combining chance and self-organization, in Proc. Nat. Acad. Sci., 2022 Vol. 119 No. 49 e2217606119 https://doi.org/10.1073/pnas.2217606119

## Selected Publications

### Books

R. L. Bras, I. Rodríguez-Iturbe, Random Functions and Hydrology (Addison-Wesley, 1985).

I. Rodríguez-Iturbe, A. Rinaldo, Fractal River Basins: Chance and Self-Organization (Cambridge University Press, 2001).

I. Rodriguez-Iturbe, A. Porporato, Ecohydrology of Water-Controlled Ecosystems. Soil Moisture and Plant Dynamics (Cambridge University Press, 2005).

A. Rinaldo, M. Gatto, I. Rodriguez-Iturbe, River Networks as Ecological Corridors. Species, Populations, Pathogens (Cambridge University Press, 2020).

### Papers

Rodríguez-Iturbe, J. M. Mejía, The design of rainfall networks in time and space. Water Resour. Res. 10, 713–728 (1974).

R. L. Bras, I. Rodríguez-Iturbe, Rainfall network design for runoff prediction. Water Resour. Res. 12, 1197–1208 (1976).

I. Rodríguez-Iturbe, D. R. Cox, V. Isham, Some models for rainfall based on stochastic point processes. Proc. R. Soc. London A 410, 269–288 (1987).

I. Rodríguez-Iturbe, D. R. Cox, P. S. Eagleson, Spatial modeling of total storm rainfall. Proc. R. Soc. London A 403, 27–50 (1986).

I. Rodríguez-Iturbe, V. K. Gupta, E. Waymire, Scale considerations in the modeling of temporal rainfall. Water Resour. Res. 20, 1611–1619 (1984).

E. Waymire, V. K. Gupta, I. Rodríguez-Iturbe, A spectral theory of rainfall intensity at the meso-β scale. Water Resour. Res. 20, 1453–1455 (1984). I. Rodríguez-Iturbe, Scale of fluctuation of rainfall models. Water Resour. Res. 22, 15S–37S (1986).

I. Rodríguez-Iturbe, P. S. Eagleson, Mathematical models of rainstorm events in space and time. Water Resour. Res. 23, 181–190 (1987)

I. Rodríguez-Iturbe, J. B. Valdés, The geomorphologic structure of hydrologic response. Water Resour. Res. 15, 1409–1420 (1979).

I. Rodríguez-Iturbe, M. González, R. L. Bras, A geomorphoclimatic theory of the instantaneous unit hydrograph. Water Resour. Res. 18, 877–886 (1982).

D. E. Tarboton, R. L. Bras, I. Rodríguez-Iturbe, The fractal nature of river networks. Water Resour. Res. 24, 1317–1322 (1988).

A. Rinaldo, R. Rigon, E. Ijjasz-Vasquez, R. L. Bras, I. Rodríguez-Iturbe, Self-organized fractal river networks. Phys. Rev. Lett. 70, 822–825 (1993).

A. Rinaldo, W. E. Dietrich, R. Rigon, G. K. Vogel, I. Rodríguez-Iturbe, Geomorphological signatures of varying climate. Nature 374, 632–635 (1995).

I. Rodríguez-Iturbe et al., Energy dissipation, runoff production, and the 3-dimensional structure of river basins. Water Resour. Res. 28, 1095–1103 (1992).

A. Rinaldo, R. Rigon, J. R. Banavar, A. Maritan, I. Rodríguez-Iturbe, Evolution and selection of river networks; statics, dynamics, and complexity. Proc. Natl. Acad. Sci. U.S.A. 111, 2417–2424 (2014).

D. G. Tarboton, R. L. Bras, I. Rodríguez-Iturbe, On the extraction of channel networks from digital elevation data. Hydrol. Processes 5, 81–100 (1991).

I. Rodríguez-Iturbe, E. J. Ijjasz-Vásquez, R. L. Bras, D. G. Tarboton, Power-law distribution of mass and energy in river basins. Water Resour. Res. 28, 1089–1093 (1992).

A. Maritan, A. Rinaldo, R. Rigon, A. Giacometti, I. Rodríguez-Iturbe, Scaling laws for river networks. Phys. Rev. E 53, 1510–1515 (1996).

I. Rodríguez-Iturbe, A. Porporato, L. Ridolfi, V. Isham, D. R. Cox, Probabilistic modeling of water balance at a point: The role of climate, soil and vegetation. Proc. R. Soc. A 455, 3789–3805 (1999).

I. Rodriguez-Iturbe, Ecohydrology: A hydrologic perspective of climate-soil-vegetation dynamics. Water Resour. Res. 36, 3–9 (2000).

A. Porporato, P. D’Odorico, F. Laio, I. Rodríguez-Iturbe, Hydrologic controls on soil carbon and nitrogen cycles. I. Modeling scheme. Adv. Water Res. 26, 45–58 (2003).

P. D’Odorico, F. Laio, A. Porporato, I. Rodríguez-Iturbe, Hydrologic controls on soil carbon and nitrogen cycles. II A case study. Adv. Water Res. 26, 59–70 (2003).

I. Rodríguez-Iturbe, P. D’Odorico, A. Porporato, L. Ridolfi, Tree-grass coexistence in savannas: The role of spatial dynamics. Geophys. Res. Lett. 26, 247–250 (1999).

T. M. Scanlon, K. K. Caylor, S. A. Levin, I. Rodríguez-Iturbe, Positive feedbacks promote power-law clustering of Kalahari vegetation. Nature 449, 209–212 (2007).

E. Zea-Cabrera, Y. Iwasa, S. A. Levin, I. Rodríguez-Iturbe, Tragedy of the commons in plant water use. Water Resour. Res. 42, W06D02 (2006).

S. Thompson, S. A. Levin, I. Rodríguez-Iturbe, Linking plant disease risk and precipitation drivers: A dynamical systems framework. Am. Nat. 181, E1–E16 (2012).

R. Muneepeerakul, J. S. Weitz, S. A. Levin, A. Rinaldo, I. Rodríguez- Iturbe, A neutral metapopulation model of biodiversity in river networks. J. Theor. Biol. 245, 351–363 (2007).

R. Muneepeerakul et al., Neutral metacommunity models predict fish diversity patterns in Mississippi-Missouri river basin. Nature 453, 220–223 (2008).

I. Rodríguez-Iturbe, D. Entekhabi, R. L. Bras, Nonlinear dynamics of soil moisture at climate scales: 1. Stochastic analysis. Water Resour. Res. 27, 1899–1906 (1991).

D. Entekhabi, I. Rodríguez-Iturbe, F. Castelli, Mutual interaction of soil moisture state and atmospheric processes. J. Hydrol. 184, 3–17 (1996).

Z. Chen, B. P. Mohanty, I. Rodríguez-Iturbe, Space-time modeling of soil moisture. Adv. Water Res. 109, 343–354 (2017).

J. M. Nordbotten, I. Rodríguez-Iturbe, M. A. Celia, Non-uniqueness of evapotranspiration due to spatial heterogeneity of plant species. Proc. R. Soc. A 462, 2359–2371 (2006).

C. Dalin, M. Konar, V. Hanasaki, A. Rinaldo, I. Rodríguez-Iturbe, Evolution of the virtual water trade network. Proc. Natl. Acad. Sci. U.S.A. 109, 5989–5994 (2012).

## Links

AGU Landbein Lecture by Ignacio Rodriguez-Iturbe (2000) Hydrological Sciences Tomorrow - Self-Organisation in Ecohydrology

Seminar by Ignacio Rodriguez-Iturbe, University of Cantabria (2002) Hidrología y biodiversidad, eslabón crucial para un futuro sostenible (in English)

Seminar by Ignacio Rodriguez-Iturbe following Honorary Degree from University of Cantabria (2012) Agua. Clave para el desarrollo sostenible (in English)

Seminar by Ignacio Rodriguez-Iturbe (2013) Vegetation patterns in semiarid river basins

A Video of the Memorial Meeting for Ignacio Rodriguez-Iturbe held at Texas A&M University at College Station, Texas in 2022 can be found here