The 2017 Alfred Wegener Medal & Honorary Membership is awarded to Murugesu Sivapalan for outstanding research on hydrological predictions in changing environments with new paradigms of watershed thermodynamics and similarity, as well as leadership of initiatives in ungauged basins.
Murugesu Sivapalan is a world leader in predicting catchment behaviour in a changing environment. In the 1980s he developed concepts of similarity linking point data of precipitation to water runoff from larger areas, leading to the notion of the ‘representative elementary area’ as a building block scale for distributed watershed models. Sivapalan developed a new paradigm of watershed thermodynamics that averages the balance equations for mass, momentum, energy and entropy in a way that is consistent with watershed processes. He and his students derived a constitutive theory, on the basis of the second law of thermodynamics, which led the way from empirical models to predictive models with sound theoretical underpinnings. He then embarked on the general problem of predictions in ungauged basins. The methods he developed, together with colleagues, are specifically geared towards estimating water resources availability in areas where few data are available, a key achievement for solving real-world water resource problems. He masterminded and led the international Predictions in Ungauged Basins initiative, which resulted in a quantum leap in the scientific community’s coherent understanding of hydrological prediction methods and processes. More recently, Sivapalan’s research has evolved to address the general and broader problem of the interplay of people and water in the Anthropocene. He was a pioneer in the field of socio-hydrology by developing concepts and models that account for the dynamic feedbacks between human actions and water resource availability, which is essential for robust predictions of water resources over long periods of time. Throughout his career, Sivapalan has been a strong advocate of synthesis. He has led a number of National Science Foundation-funded projects on hydrologic change where he synthesised disparate research into a coherent strand of enquiry. He provided conceptual underpinnings for linking water flow processes with chemical, biotic and erosional processes, accounting for the associated hydrological, biogeochemical and morphological changes. His holistic research approach has been a real enabling factor not only for his own research but for the Earth science community at large.