Simulating the interrelationships among population, water, ecology, and economy in urban agglomerations based on a system dynamics approach

Abstract

China's urban agglomerations (UAs) gather most of China's population and economy, but they also facing serious water resources crisis and ecological risks. How to manage the interrelationships among the population, water, ecology, and economy (PWEE) in UAs is crucial for the future of China's urbanization development. Based on the system dynamics (SD) approach, we constructed an SD model for simulating the interrelationships among PWEE in UAs, elucidating the intricate nonlinear relationships between elements of the PWEE system through causal feedback processes and model equations. In addition, we take the Tianshan North slope urban agglomeration (TSNSUA) as an example, which is a representative area where water resources crisis and ecological risk coexist, and designed five scenarios to dynamically simulate the balance of water supply and demand under the high-density population and economic agglomeration, as well as the potential ecological environmental effects in the process of urban spatial expansion. Our findings include: (1) The existing water resources conditions of TSNSUA can continue to support the current population and economic growth rates. If the future development plan follows the status quo continuation scenario, the phenomenon of insufficient water supply will not occur on the premise that the water supply capacity remains at its current highest level. (2) TSNSUA's future urban spatial expansion is predicted to have less overall impact on the ecological environment, and the carbon peak target by 2030 has an opportunity to be achieved. (3) Appropriately reducing the proportion of agricultural water, while strengthening water-saving and ecological protection measures, can ensure that TSNSUA's population and economy maintain a medium to high growth rate. Based on scenario comparison, our recommendation to policymakers is to establish the development objectives of TSNSUA based on the comprehensive development scenario.