The urban water system theory is the application and extension of watershed hydrological science to an urban scale. In a paper published in Science China Earth Sciences, a research group led by Chinese academician Xia Jun introduced the urban water system 5.0 theory and associated model. This study aims to advance interdisciplinary study in urban water sciences and offer a systematic solution to complex urban water issues. The urban water system theory is the application and extension of watershed hydrological science to an urban scale. In a paper published in Science China Earth Sciences, a research group led by Chinese academician Xia Jun introduced the urban water system 5.0 theory and associated model. This study aims to advance interdisciplinary study in urban water sciences and offer a systematic solution to complex urban water issues. Earth Sciences Environment Phys.org – latest science and technology news stories