Flood mitigation performance of low impact development practice in a coastal city from the perspective of catchment scale

Abstract

Climate change and urbanization have imposed significant stress on urban drainage systems, resulting in hydraulic overloading and urban flooding. The implementation of Low Impact Development (LID) practices exhibits promising potential in mitigating these impacts. In this study, a modeling task was proposed for the drainage district of Haikou City, Hainan Province, China. The tracer-aided urban flood model was employed to conduct 64 simulation scenarios, aiming to evaluate the hydrological response of LID strategies under varying rainfall intensity, spatial distribution, and initial saturation level. The results have demonstrated the significant utility of the tracer-aided urban flood model in assessing the hydrological impact of LID practices, particularly in accurately identifying both the source area and hazard area affected by flooding. Notably, rainfall intensity plays a crucial role in influencing the hydrological response of LID practices. With the increase in rainfall intensity, the efficacy of LID strategies in mitigating value of peak flood volume gradually intensifies, but the reduction rate of peak flood volume diminishes progressively. In terms of LID strategies with varying spatial distributions, the upstream strategy outperforms both midstream and downstream strategy. Nevertheless, the correlation between reduction value of flood volume across different catchments suggests a complex synergistic effect among them. The reduction value of LID practices on flood volume will gradually decrease as the initial saturation increases, indicating that careful consideration should be given to the impact of rainfall patterns on their initial saturation when incorporating LID practices into an urban flood mitigation strategy. This study provides valuable insights into sustainable stormwater management by examining the effectiveness and influencing factors of LID practices.