Rainfall Pattern Construction Method Based on DTW-HCA and Urban Flood Simulation: A Case Study of Nanchang City, China

Due to the different design standards of urban drainage and water conservancy facilities, numerous coordination and linkage issues arise when confronting extreme rainfall. In this paper, three clustering methods were used to cluster rainfall events, and the results demonstrate that the dynamic time warping-hierarchical clustering algorithm (DTW-HCA) effectively captures the temporal similarity of time series. Then, the Pilgrim and Cordery rainfall distribution method was utilized to extract the characteristics of eight clusters of rainfall events, and eight kinds of rainfall patterns were obtained. Last, after importing the rainfall patterns into the MIKE model of Qingshan Lake to conduct flood simulations, the impacts of different rainfall patterns on municipal systems and water conservancy systems were assessed by the depth and area of urban waterlogging, as well as the water levels and discharge of rivers. Based on this, three rainfall patterns are proposed as a designed rainfall pattern (DRP), an extreme rainfall pattern for urban drainage facilities verification (ERPUDFV) and an extreme rainfall pattern for water conservancy facilities verification (ERPWCFV), which aim to provide a reference basis for designing region-specific extreme rainfall patterns, as well as the verification of urban drainage and water conservancy facilities.