Comparative study on spatial and temporal distribution characteristics of meteorological drought in the upper and middle reaches of Huai River Basin based on SPI and SPEI
This study analyzed the spatial and temporal distribution characteristics of annual and seasonal meteorological droughts using the drought indices of standardized precipitation index(SPI) and standardized precipitation evapotranspiration index(SPEI), and the mathematical statistical methods of linear trend method, Mann-Kendall test and wavelet analysis methods, based on the monthly precipitation and temperature data of Huai River basin from 1960 to 2017. The results showed that: the annual, summer and winter drought index of the basin showed a slight increasing trend, and the SPEI increased slightly more than SPI. The spring and autumn drought index showed a slight decreasing trend, and the SPEI decreased slightly more than SPI. The two drought indices agreed well reflecting dry and wet cycles in the same area during the research period. In the annual scale, SPEI showed that the frequency of moderate drought was higher in the north area of Huai River, but SPI showed that the frequency of mild drought was higher. The different drought frequencies were similar in the northern and southern area in other time scales. The spatial variation trend of the two drought indices was similar except in summer. The drought trend of SPEI was slightly stronger than that of SPI in the same region in the year and spring and autumn seasons. SPI showed that most of the regions were wetter while SPEI showed a drought trend in winter. There were significant differences in spatial distribution between the two indices. The drought frequency shown by SPEI in four seasons was generally higher than that by SPI statistics. The results have important reference value for drought objectivity assessment and flood and drought disaster prevention and management.