Abstract:

Using the minute-level precipitation data from 1961 to 2018, the short-term rainstorm process in Tianjin was counted, and the rainstorm process was classified with the fuzzy recognition method. The temporal and spatial distribution characteristics of the rainstorm type were analyzed. Based on the urban rainstorm internal waterlogging numerical model of Tianjin, the impacts of different rain patterns on the total amount of waterlogged were assessed. The results showed that in the past 58 years, the short-term rainstorm in the Tianjin area is dominated by unimodal type (type I, type II, and type III), and the 60-minute rainstorm in each period is dominated by type Ⅰ and type Ⅲ. The 120-minute and 180-minute rainstorms are dominated by Type I. Short-term rainstorms occur concentratedly in July and August, and the rainstorm process is dominated by unimodal type. The 60-minute rainstorm type is almost type I in July, and type III is the most in August. Both the 120-min and 180-min rainstorm types are mainly Type I. The short-term rainstorm patterns in each area are mostly unimodal type, following the bimodal type and less the uniform type. From the perspective of dominant rainfall patterns in various regions, the 60-minute and 180-minute rainstorms are different, including type I, type III, and type V. The 120-minute rainstorm type is consistent with type I in all areas. There is obvious spatiotemporal differentiation in short-term rainstorm patterns in Tianjin, and different rain patterns affect the peak occurrence time of the total amount of waterlogging. Among them, the peak time of the total amount of waterlogging of type I appears early, which is the rain type that the urban drainage design focuses on. In summary, the impact of climate change and urbanization on the process of heavy rain should be fully considered in the engineering design.

Key words: Short-duration rainstorm pattern, Spatiotemporal differentiation, Waterlogging, Unimodal type, Fuzzy identification method