Space-time approach to water environment carrying capacity calculation

China has faced the challenge of defending its water environment in the face of rapid economic development. This fact highlights the urgency to adopt water environment carrying capacity (WECC) as a measure for the sustainable development of human society. Recent scientific research tends to focus on the interaction of whole systems in a macro top-down way based on statistical data and an index setting in a uniform study unit, whereas its internal spatial heterogeneity and the spatial function between each subsystem, such as population, economy and water environment, have received little attention. An integrated model is presented based on the system dynamics (SD) and cellular automaton (CA) models in this study. Spatiotemporal water environment carrying capacity analysis during the process of urban evolution is attempted and realized in Changzhou, China. In 2010 y and 2025 y, the control units 1, 2, 5, 6, 9, 11 are in a relative worse status of water environment and should be taken measures to increase local water environment carrying capacity, the control unis 4, 8, 12, 13 are still in a good status of water environment, while the overall water environment carrying capacity of study region is overloaded. In 2050 y, the control units 3, 4, 8, 10, 12, 13 are in a good status of water environment which are consistent with the status of the whole study region, the control units 1, 2, 5, 6, 7, 9, 11 are opposite and should still be adopted measures. The results would provide a basis for reasonable industry and population patterns according to water environment capacity.