Improvement of City Rainfall Model Subcatchment Structure Based on Urban Hydrology Process

This study proposes a hierarchical approach to urban subcatchment division that incorporates topography and road network factors, as well as a subcatchment-pipe network connection strategy. By taking into account all relevant hydrological components and the efficiency of drainage networks, the precision of urban flooding simulation is boosted. The suggested approach makes use of each stormwater well in the subcatchment as a confluence outlet. The intensity variations of flood simulations conducted using the traditional Thiessen polygon method and the proposed method are compared. The current study focused on the area of Panyu District in Guangzhou City, China. Using the InfoWorks ICM model, four comparison scenarios were made to simulate flooding conditions during four return periods. The results suggest the following: (1) While maintaining the production and confluence parameters at a constant level, the simulation results of flooding present discrepancies depending on the methodology used for subcatchment division and confluence connection with the pipe network system. (2) The utilization of the Thiessen polygon method for subcatchment division results in a certain degree of overestimation of the flooding condition as compared to the more comprehensive subcatchment classification. (3) When considering all the collection nodes inside the subcatchment, the estimation of the inundation situation is notably lower compared to when only a single stormwater well is chosen as the subcatchment outlet. In the event of 100-year rainfall, the overall overflow can be decreased by 8.44%. A more accurate model is a solid foundation for mimicking reality. This study revises the urban stormwater model, and the proposed enhancement is applicable to simulations of urban waterlogging in any global region and can guide the development of a more scientific approach to urban water management.