By Ciaran Harman –

Dr. Ciaran Harman

I’ve been asked say some words on the topic of “Why Professor Sivapalan?”

I am a former PhD student of Siva, as he is known to his friends. It might seem unconventional for Siva to ask someone so young and untenured to give this kind of address. Shouldn’t a more senior colleague be appropriate? Someone whose own long history of awards and recognition would impress upon you all Siva’s worthiness for the position of endowed chair. But to those of us who know him, this choice is quite typical of Siva.

Now, senior colleagues have given this kind of introduction in the past: Siva has been well-recognized by his peers for his intellectual contributions, and for his leadership. He has received the “grand slam” of hydrology awards: the Dalton Medal from the European Geosciences Union, the Horton Medal from the American Geophysical Union, and the International Hydrology Prize from UNESCO. He is one of only three people to have won all three awards. Perhaps in choosing a former student this time, he just thought he’d shake things up a little. That would be quite typical.

To understand why Siva is so highly regarded, you need to understand a little history. Hydrology has, in large part, focused on solving important practical problems, like knowing how much drinking water we can reliably draw from a dam, or a well.

But for some, hydrologic science is something more.

The transformation of falling rain into a surging river is, for them, the result of a vast network of interactions in the landscape: rock and soil, hills and valleys, heat and light, plants and people. This network is renewed and revised with each storm, and with each drought. It creates the hydrologic system, and is sustained by it. Hydrologic scientists have sought to understand this system deeply.

*Photo – Dean Cangellaris congratulating Professor Sivapalan

In the 1960s and 70s this work took off, and detailed field studies revealed a tantalizing combination of order and randomness. The flow through the landscape was too variable for simple idealizations to do it justice, but it shimmered with patterns that hinted: deeper insights are possible.

But hydrologic science lacked its own body of theory, its own set of abstractions that could make sense of the hydrologic system on its own terms, and might lay bare an inner structure and organization.

At the start of the 1980s, Siva arrived in the US to begin graduate studies at Princeton. Over the next 35 years, along with the students and colleagues he inspired and led, Siva has helped lay the foundation for such a hydrologic theory.

Siva’s career and contributions can be broadly divided into three parts.

During his PhD, and in the decade after with his students at the University of Western Australia, Siva showed how spatial scale is a master control on hydrologic systems, and proposed ways to unify our understanding of this control. His work cut through conceptual confusions. A landmark review paper written with a young colleague, Guenter Bloschl, now president of the European Geosciences Union, laid out the issue with unsurpassed clarity and insight, and has been cited over 500 times.

Characteristically, Siva used simple models to generate deep insights, revealing how shifts in the hydrologic dynamics of watersheds of different scales arises from shifts in the balance between competing forces in that vast network of interactions. Few can pull off this kind of high-wire balance of simple-mindedness and clear thinking, but Siva’s work persuaded with an elegance that was above reproach.

Siva cemented his role as an international leader in the second part of his career, as the driving force behind the Predictions in Ungauged Basins, or “PUB”, initiative – a 10-year global effort to improve hydrologic predictions in places that lack stream gauges. Siva has never forgotten his origins in the large part of the world that lacks the hydrologic data typically available in the US and Europe to solve practical hydrologic problems. He took on the task of writing the draft science plan and getting others to contribute to it. During this time Siva focused his energy much more on including other people than on his own research, in the expectation that the science would follow naturally from getting the right people working in the right direction. Travelling tirelessly from his home in the most isolated large city in the world, he focused the passion of a huge global community of like-minded scientists towards a common goal of great practical significance. The wealth of new ideas and energy that was generated during the PUB decade are a testament to the wisdom of his approach.

Over time, the importance of understanding hydrologic systems deeply has become more and more clear. Many of the traditional methods of applied hydrology rely on an assumption that the future will look much like the past. In the face of accelerating climate and landscape change, this assumption is no longer tenable. Now, in this third part of his career, Siva has made the issue of predictions under change his central focus. In characteristic style he is today seeking fundamental insights into the way human society and hydrologic systems interact and change each other over time, and his enthusiasm is drawing in like-minded scientists under a new umbrella of “sociohydrology”.

Before I end this introduction let me say some more personal words about Siva. In the last few weeks I contacted other former students who worked with Siva at all stages of his career to help me write these remarks. Three of Siva’s habits came up in many of the responses: One is his tendency at seminars to ask beguilingly simple questions that nevertheless stump the speaker. Often the “Siva question”, as it is sometimes referred to, boils down to a genuinely curious “Why is this important?”

The second is the image he invokes when urging a student to look up from the nitty-gritty details, and to keep their sights on what is really creative, important, and groundbreaking: “You’ve got to cut across the jungle!” I think every one of his graduate students has heard him say this dozens of times.

The third is the way his exceptional mentoring of graduate students is grounded, in part, by his humility. Siva clearly recalls what it was like to be leaving your home and going far away for graduate school, or to be at your first big international conference as a nervous foreign student that no one cares to talk to, or to be starting out as a new junior faculty member, wanting to prove yourself and afraid of failure.

Siva is today one of the most well-known and recognizable figures in the hydrologic community, but the frequent advice he gives to young scientists still rings true: that you shouldn’t strive for awards and recognition and to be the biggest guy in the room – just find an important question and to try to answer it – and then all the other stuff will come.

In answer then to the question of “Why Siva?” I would say: because that is exactly what he has done.

*I am grateful to Rebecca Gianotti, Matt Hipsey, Hongyi Li, Gavan McGrath, Justin Robinson, Stan Schymanski, Richard Silberstein, Gajan Sivandran, Sally Thompson, and Ross Woods, whose recollections (and sentences in several cases) contributed to the writing of this.