Characteristics of Regional Extreme Short-time Rainstorm in Mulan River Basin
To explore the characteristics and causes of spatio-temporal distribution and rain duration distribution of regional extreme short-time rainstorm in Mulan River Basin,this article analyzes spatio-temperal characteristics and weather background of the extreme rainfall processes by using the hourly precipitation data of Mulan River Basin from 2010 to 2020.Besides,the temporal distribution characteristics of rainfall are analyzed by means of fuzzy identification algorithm.The results are as follows:(1)The impact weather system is frontal or typhoon system.The duration,influence range and accumulated rainfall of the typhoon-type process are obviously higher than that of the front-type process.(2)During the heaviest precipitation period,the front-type process has diurnal variation,while the typhoon-type process does not have such diurnal variation.Moreover,the peak of the front-type process is about 3 h later than the 60 min extreme heavy precipitation along the coast of Fujian.(3)The process of regional extreme short-time rainstorm occurs mainly from May to September,which is similar to the seasonal distribution of the rainstorm days in Putian City,but their occurrence frequency in July accounts for a different proportion in the whole year,with the former accounting for the highest proportion and the latter only ranking the third in the whole year.(4)The rain duration distribution of the extreme rainfall process shows a unimodal posterior type with high rainfall concentration,while severe rainfall mainly appears in the second half of the process.The temperature after sunset is lower than that in the afternoon,which is conducive to the rapid transit of the front,stimulates the complete release of unstable energy,and makes the rainfall concentration of the front type process high.The reasons for the high rainfall concentration in typhoon-type process is not only limited by the extreme process algorithm itself,but also related to the consistent movement of the typhoon center and the severe rainfall area as well as the mesoscale characteristics of the severe convection inside the typhoon.The advantages of bell shape and basin topography in thermal and dynamic conditions make the middle and upper reaches of Bangtou Creek,Daji Creek and Yanshou Creek prone to extreme short-time rainstorm.Therefore,it is necessary to pay attention to the violent rise of water level in Mulan River caused by extreme short-time rainstorm.
river regionextreme short-time rainstormrain durationconcentration degree
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万方数据
