Analyzing the impact of polder-type flood control pattern on river system's regulation and storage capacity under urbanization

The rapid development of urbanization has led to changes in the morphology and structure of the river system, exacerbating flooding in the basin and seriously affecting the regulation and storage capacity of the river system. We propose the evaluation indexes of the regulation and storage capacity, establish a hydrological–hydrodynamic model to investigate the effects of the polder-type flood control pattern on the regulation and storage capacity during urbanization. The results show that the river system's static regulation and storage capacity exhibits a decreasing trend during the urbanization process. The change in static regulation and storage capacity of low-grade rivers has a more significant impact on the total regulation and static storage capacity. The construction of polders increases the flood pressure of the river system and reduces the dynamic regulation and storage capacity. The smaller the size of the flood, the more pronounced the effect. With the increase in flood-protected areas, the dynamic regulation and storage capacity gradually decreases, and minor flooding is more sensitive to the number of polders.