Research on Runoff Management of Sponge Cities under Urban Expansion.

To integrate the sponge city concept into urban development, we propose an analytical approach for runoff volume control, considering urban expansion. Using Changchun City as a case study and historical land-use data, we simulated the prediction of Changchun City's land-use structure for 2035 change with the GeoSOS-FLUS platform. We calculated storage volumes for Low Impact Development (LID) designs using 2019 and 2035 land surface data. The objective is an 80% runoff volume control rate by 2035. Through Monte Carlo simulation and sensitivity analysis, we assessed the impact of various land-use types on LID storage volume calculations. Findings show that industrial land significantly influences LID storage volumes. This highlights the need for precise surveys of industrial land properties and surface composition in sponge city planning for more accurate runoff volume control analysis in Changchun City. The results indicate that LID storage volumes based on current data may not meet long-term sponge city goals due to increased impervious surfaces and runoff coefficients during urbanization. [ABSTRACT FROM AUTHOR]