Analysis of spatio-temporal distribution of rainstorms in the western region of Taihu Lake Basin

Global warming and rapid urbanization development would affect the rainfall structure (i.e., variability in space and time) and the frequency of extreme hydrometerological events. To analyze the spatio-temporal distribution of rainstorms in the western region of Taihu Lake Basin (TLB) in the changing environment, daily rainfall data from rainfall stations from 1961 to 2015 are analysed to determine the spatial and temporal trends of 4 rainstorm indices (annual days, rainfall, intensity and percentage of rainstorms). Furthermore, the annual maximum daily rainfall for the specific return period is calculated. The results show that: (1) Annual rainfall increases from the north to the south, while annual days and rainfall of rainstorms decrease from the north and south to the center in the western region of TLB. Annual intensity of rainstorms increases firstly, and then reduces from the southwest to the northeast, while annual percentage of rainstorms in the southwest is lower than other places in the western region of TLB. (2) Annual days, rainfall and percentage of rainstorms at Yixing station have risen sharply from 1961 to 2015. (3) From 2005, there is a significant increase in all the rainstorm indices in the western region of TLB. (4) The average annual maximum daily rainfall at Jintan and Danyang stations appear higher than those at Liyang and Yixing stations. (5) The annual maximum daily precipitation for 5-year return period at the 4 representative stations (i.e., Danyang, Jintan, Liyang, Yixing stations) all exceed 100 mm to be classified as heavy rainstorms. Particularly, Jintan and Danyang stations are prone to suffer from extreme rainfall events compared with Yixing and Liyang stations.