Hydrological processes have been changing due to the dual impacts of climate changes and human activities, and modeling the hydrological processes and changes has long been the goal of the global hydrological communities. Challenges still exist, such as lacking effective models and in-situ observation data, uncertainties related to the climate change prediction and human activities estimation and monitoring. This session aims to discuss these challenges, propose solutions and report latest results on modeling the hydrological processes and changes of world river systems and urban areas, topics to be addressed but not limited to are urbanization and climate changes in the past and future at city, watershed or regional scale, from the continent to the coastal areas; observation and simulation of hydrological processes and changes in large rivers and greater urbanized areas; Hydrological models and tools, uncertainties and controlling methods; hydrological response changes induced by climate changes and human activities.