Diogo Bolster is an outstanding scientist who has made fundamental contributions to the grand challenge in groundwater hydrology, namely, how flow and transport processes can be predicted under spatial heterogeneity. Bolster has fundamentally changed the accepted model of how contaminants move through aquifers and mix and react with surrounding waters on the way.

This problem is challenging because heterogeneity is ubiquitous, it is multiscale, it causes scale effects, and it induces uncertainty in large-scale process descriptions. The mathematics that hydrogeologists have used for many decades has had limited predictive capabilities, which strongly hinders its ability to be used by practitioners to solve important, real-world problems about water quality. Bolster’s work has made mathematical hydrogeology applicable by developing predictive capabilities under uncertainty, which helps us fundamentally understand, model, and upscale these concepts to real-world problems. His approach is multidisciplinary in that it unites methods from fluid dynamics, statistical physics, and applied mathematics. Bolster is revolutionizing the theoretical underpinnings of many other aspects of hydrology, too, including transport and biochemical reactions in streams and hyporheic zones, vadose zone predictions, and watershed-scale modeling. Bolster is a remarkably prolific researcher and takes ideas to practice, and he also shares his work freely to the community, including code he has developed that is easily downloadable from his website.

Equally important, Bolster collaborates broadly and is a thoughtful leader and mentor. He looks to train the “whole student” and encourages his students to pursue whatever they are interested in outside of research. His graduate students have taken courses in music, film, philosophy, leadership, and business. Bolster is rigorous in his expectations with students and postdocs but kind and generous with his time, and is one of the most welcoming, easygoing, and friendly collaborators many of us have. He can distill complex hydrologic, ecological, and mathematical concepts into concise and easily understandable points. He is also a leader in our community, and provides strong and consistent leadership even among senior colleagues, including those on the board of directors of the Consortium of Universities for the Advancement of Hydrologic Science Inc. (CUAHSI) and in reports for the National Academies. Bolster’s research impact, thoughtful leadership, and inspiring mentorship make him a wonderful choice for the inaugural Polubarinova-Kochina Hydrologic Sciences Mid-Career Award.

—Kamini Singha, Colorado School of Mines, Golden

I am truly humbled to be the inaugural recipient of the Polubarinova-Kochina Hydrologic Sciences Mid-Career Award. Who could ask for anything more than to work in an area that they love, where we get to disentangle the mysteries of the natural world and hopefully improve society and well-being as a consequence? And to do so while working with so many great people: my early teachers, who inspired me to enjoy and appreciate the beauty of mathematics and science; my Ph.D. and postdoc mentors, who taught me so much about how to ask the right questions and then tackle them patiently while giving me absolute freedom to explore my own curiosities; my wonderful colleagues, collaborators, and friends who are part of the AGU hydrology community, who inspire my curiosity every time I talk with them and with whom I just enjoy spending time; my undergraduate and graduate students, who bring me great joy as I see them grow and foster their own curiosities, knowing that I played some small role in that; and then of course my family and friends, who have supported and encouraged me all of the way. It is this entire community of people who make me feel energy and enthusiasm for what I do, and to all of you I just say thank you. I am blessed to have you all in my life, and it is an honor to work with you all. —Diogo Bolster, University of Notre Dame, Notre Dame, Ind.