Abstract
Abstract Using the global Moran's I and other statistical methods, the spatio-temporal variation characteristics of extreme precipitation over the Dongting Lake basin are studied based on the daily precipitation at national meteorological stations from 1960 to 2016. The results show that the spatial distribution of extreme precipitation is very uneven. The areas with the maximum of extreme precipitation are located in the Lishui River basin, the middle reaches of the Zishui River and the lower reaches of the Yuanshui River. There is more extreme precipitation on the windward slope than in the basin and the lake area. There are two typical modes for extreme precipitation after the empirical orthogonal function decomposition, namely the north–south mode and the northwest–southeast mode. The extreme precipitation event is more likely to occur in the northwestern and southeastern areas of the Hunan Province. There is an obvious spatial clustering of extreme precipitation over the Dongting Lake basin. The global Moran's I is positive. In addition, the extreme precipitation at most meteorological stations shows an increasing tendency. Also, the middle reaches of the Yuanshui River basin and the Zishui River basin have the most significant increasing tendency. The abrupt change of extreme precipitation occurred around the late 1980s.
Highlights
The Dongting Lake is the second largest freshwater lake in China
Based on the daily precipitation data at 97 national meteorological stations in the Dongting Lake basin (Figure 1) from 1960 to 2016, this study systematically studies the spatio-temporal variation characteristics of annual maximum daily precipitation and annual maximum accumulated precipitation in a single rainfall event in the whole basin using several analytical methods such as the empirical orthogonal function (EOF) decomposition, the global Moran’s I index, the linear regression method, the Mann–Kendall test and the complex Morlet wavelet transform, in order to comprehensively reveal the climatic characteristics of extreme precipitation in the Dongting Lake basin and provide a useful reference for the flood prevention operation
Variation and abrupt change analysis of extreme precipitation The inter-annual variations of the annual maximum daily precipitation and the annual maximum accumulated precipitation in a single rainfall event are analyzed using the linear regression method. It can be seen from the linear trend distribution of annual maximum daily precipitation and annual maximum accumulated precipitation in a single rainfall event in the Dongting Lake basin (Figure 6) that the stations with the most significant increase of extreme precipitation are mainly located in the middle reaches of the Yuanshui River and the Zishui River, which are all along the Xuefeng Mountain
Summary
The Dongting Lake is the second largest freshwater lake in China. The whole basin has a well-developed water system and a relatively concentrated population. Based on the daily precipitation data at 97 national meteorological stations in the Dongting Lake basin (Figure 1) from 1960 to 2016, this study systematically studies the spatio-temporal variation characteristics of annual maximum daily precipitation and annual maximum accumulated precipitation in a single rainfall event in the whole basin using several analytical methods such as the EOF decomposition, the global Moran’s I index, the linear regression method, the Mann–Kendall test and the complex Morlet wavelet transform, in order to comprehensively reveal the climatic characteristics of extreme precipitation in the Dongting Lake basin and provide a useful reference for the flood prevention operation. The annual maximum daily precipitation and the annual maximum accumulated precipitation in a single rainfall event at 97 meteorological stations are, respectively, counted
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