Solving the Global Water Crisis at Scale - A Tribute to Afeefa Rahman

Abstract

Freshwater scarcity is growing faster than the means to manage it. Conservation and recycling can stretch the use of existing supply but cannot enlarge it, and the sources of new supply are limited, and groundwater, and snowpack are shrinking under overuse and a warming climate. The environmental impact of desalination limits its expansion.

With Afeefa Rahman, a PhD student, we explored to solve this problem at scale. This was based on noting that the air just above the ocean is replenished with water vapor continuously from solar evaporation. Our strategy aimed to capture humid air offshore, and condense it to generate potable water. The questions were whether the marine atmosphere holds enough moisture to supply large population centers near coastal areas, whether that supply persists as the climate warms, whether the sea area feeding an intake is too small to disturb regional rainfall, and whether the approach can rival desalination on cost while producing no brine. The research paper in Nature Scientific Reports, using decades of reanalysis and climate projections, answered yes to each of these questions.

The engineering challenge of capturing the moisture and then condensing it is formidable. How do we design an intake structure that maximizes the capture of moist air across the diurnal, seasonal and interannual variability? The research used large-eddy simulations (LES) to test intake geometries. How do we cool such large volumes of moist air that is energy efficient? We explored using membrane based separation of moisture from oxygen and nitrogen, so cooling energy is only needed for the water vapor.

Afeefa passed away in May 2026, before this work could be defended as a PhD thesis. This seminar will present the work as completed.

Bio
Professor Praveen Kumar holds a B.Tech. (Indian Institute of Technology, Bombay, India 1987), M.S. (Iowa State University 1989), and Ph.D. (University of Minnesota 1993), all in civil engineering. Kumar joined as faculty at the University of Illinois in 1995 where he has been ever since. Prior to joining the University of Illinois, he was a research scientist (January 1993 to July 1995) at the Universities Space Research Association (USRA) and Hydrologic Sciences Branch, NASA- Goddard Space Flight Center, Greenbelt, Maryland, USA. His research deals with Hydrocomplexity, the quantitative understanding and prediction of emergent patterns of form and function that arise from complex non-linear multi-scale interactions between soil, water, climate, vegetation and human systems; and how this understanding can be used for innovative solutions to water and sustainability challenges. He has made extensive, deep and signature contributions pertaining to information theory in geosciences, biosphere-hydrosphere interactions, multi-scale variability of hydrologic processes, hydro-geomorphology and hydroinformatics. He is the leader in the study of Critical Zone in human modified environments. He presently serves as the Executive Director of the Prairie Research Institute (PRI) which houses all five of the Illinois State Scientific Surveys. He is responsible for all policy and operational decisions for PRI with over 1000 employees and about $125M annual research expenditure. He served as the Director of NSF funded (IMLCZO) Intensively Managed Landscapes Critical Zone Observatory (2013-2021) and presently serves as the Director of NSF funded (CINet) Critical Interface Network in Intensively Managed Landscapes (2020-2026).