Charles W.W. Ng is a Chair Professor and the CLP Holdings Professor of Sustainability at The Hong Kong University of Science and Technology. He is also a Fellow of the Royal Academy of Engineering, an Editor- in- Chief of the Canadian Geotechnical Journal and the immediate past- President of the International Society for Soil Mechanics and Engineering (2017– 2022). He has published over 400 SCI journal articles, many of which are related to unsaturated soil mechanics and engineering. He has received many international awards, such as the 2022 Vernes Medal from the International Consortium on Landslides, the 2022 Fredlund Award from the Canadian Geotechnical Society, the 2017 Telford Premium Prize from the Institution of Civil Engineers, and the 2016 R. M. Quigley Award from the Canadian Geotechnical Society. In addition, he has received awards in mainland China, namely the prestigious 2022 Ho Leung Ho Lee Foundation Prize for Scientific and Technological Progress, the 2020 National Natural Science Award and the 2015 Scientific Technological Advancement Award from the State Council, China. Drs Chao Zhou and Junjun Ni are former PhD students of Professor Ng and have conducted extensive research on unsaturated soil mechanics and engineering during and after their PhD studies. Dr Zhou is currently an Associate Professor at The Hong Kong Polytechnic University, and Dr Ni is a Professor at Southeast University in Nanjing, China.