Abstract: The determination of urban rainstorm intensity and rainstorm pattern serves as the basis for scientific planning and rational design of urban drainage systems. Based on the detailed precipitation data from Jinan National Basic Weather Station for 1961—2017, this paper studied the characteristics of short-duration rainstorm intensity and rain pattern change in four different periods using probability distribution model, Chicago method, and co-frequency method: 1961—1990, 1971—2000, 1981—2010, and 1991—2017. The results showed that Jinan′s short-duration rainstorm had been increasing intensity since the 1980s, and this is especially obvious since the 1990s. The short-duration and long-duration strong precipitation were all mainly concentrated in the first half of the precipitation process and had a tendency to postpone. This paper suggests that the local rainstorm intensity formula should be revised every 10 years or when the change rate of the rainstorm intensity exceeds 5%.

Key words: short duration, rainstorm intensity, rain pattern, Jinan