Analysis of urban river flood prevention under different rainfall scenarios

Abstract

[Objective] Due to the impact of global climate change and rapid urbanization in China, urban flood disasters have occurred frequently in recent years, causing immeasurable casualties and socioeconomic losses. Therefore, it is important to explore the influence of different rainfall conditions on river water level to provide scientific support for urban flood control. [Methods] Based on the current sluice operation rules of the Shima River basin, coupled with MIKE11 and SWAT models, a hydrological and hydrodynamic model of the Shima River basin was constructed. The model was employed to analyze the changes of urban river water level under different rainfall scenarios with variations in rainfall frequency, spatial distribution, and temporal processes, and to explore the impacts of different rainfall conditions on the water level of the Shima River estuary. [Results] The result showed that: continuous and concentrated rainfall in the basin caused water levels at the estuary sluice to exceed the 4.5 m alert level by 13%, while intermittent concentrated rainfall caused an exceedance of 5%. The number of sluice operations at Qiling Sluice under concentrated rainfall was 7 times higher than under dispersed rainfall conditions, and widespread heavy rainfall across the basin caused the estuary water level to reach the 4.5 m warning level multiple times. [Conclusion] The findings indicate that:(1) the simultaneous occurrence of multiple rainfall events, widespread heavy rainfall, and concentrated rainfall of short duration and high intensity increases the risk of flooding in the Shima River basin.(2) Concentrated rainfall and widespread heavy rainfall across the basin have the greatest impact on sluice operation.(3) The greater the rainfall frequency, concentration, and intensity, the greater the impact on the water level at the estuary sluice. Only heavy rainfall in the upper basin causes a rise in the estuary water level, and only heavy rainfall in the lower basin or moderate rainfall across the basin has minimal impact on the estuary water level. The hydrological and hydrodynamic model of the Shima River basin established by the study, which analyses the changes of water level at the estuary sluice under different rainfall conditions, can be used as a reference for the urban flood control and flood control scheduling in the Shima River basin.

Keywords

estuary water level / rainfall scenario / sluice scheduling / urban flood control / hydrological and hydrodynamic simulation / MIKE11 model / SWAT model / Shima River in Dongguan