Murugesu Sivapalan is an Australian-American engineer and hydrologist of Sri Lankan Tamil origin and a world leader in the area of catchment hydrology.

He held the Satish Dhawan Visiting Chair Professorship at the Indian Institute of Science, Bengaluru, and currently serves as Honorary Professor at Tsinghua University.

[14] He organized successful workshops on scale issues in Robertson, Australia, in 1993 and in Krumbach, Austria, in 1996, which had a major impact on the field.

He and his doctoral student Paolo Reggiani[15] proposed a/the thermodynamic theory framework to formulate balance equations for mass, momentum, and energy at the catchment scale and associated constitutive theory and closure relations that he introduced as a way to develop physically based hydrologic models of appropriate complexity and fidelity over what he called the representative elementary watershed (REW) scale.

[13][16] In parallel, he and students Chatchai Jothityangkoon and Darren Farmer proposed an alternative top-down, data-based methodology for the systematic development of models of appropriate complexity by focusing on reproducing signatures of hydrologic variability over a range of timescales.

[17] Recognizing the considerable uncertainty in hydrological predictions due to the inability to estimate transpiration by natural vegetation realistically, Sivapalan improved the research approach through interdisciplinary synthesis.

He and his PhD student Stan Schymanski[18] proposed and tested the principle of vegetation optimality, and in particular the maximization of net carbon profit, as a way to make prediction of evapotranspiration and water balance with minimal calibration.

Sivapalan wrote the PUB science plan, organized several workshops and conferences, and traveled around the world to promote it and mobilize the community.

The culmination of PUB was the publication of the landmark synthesis book Runoff Predictions in Ungauged Basins (Blöschl et al., 2013) by Cambridge University Press, in which Sivapalan served as an editor.

[2] Socio-hydrology presents a coevolutionary view of hydrologic systems and explores the relationship between water, human activities, landscapes, and climate.

He was executive editor of the European Geosciences Union's Hydrology and Earth System Sciences Journal, following its transition to open access.