Temporal and spatial evolution of drought in Haihe River Basin from 1960 to 2020

The Haihe River Basin is an important grain-producing area in China. It is of great significance to explore and grasp the temporal and spatial evolution of drought for drought prevention and disaster mitigation, water security, and food security. In this study, based on the standardized precipitation evapotranspiration index (SPEI), gravity center model, standard deviation ellipse, and other methods, we analyzed the temporal and spatial evolution of drought in Haihe River Basin from 1960 to 2020. The results showed that during 1960 ~ 2020, the frequency of drought in the Haihe River Basin had an upward trend, and light drought and moderate drought occurred frequently. Light drought was prone to occur in winter (January, February, December), and moderate drought mainly occurred in March (The first month of spring). The frequency of severe drought and extreme drought has increased significantly since 1990, and the monthly impact is spreading. The annual drought barycenters are distributed in plain areas such as Beijing, Hebei province, and showed a northeast to southwest zonal distribution in the basin, with a general trend of moving toward southwest. The monthly drought barycenters are mainly distributed in the central part of the basin around Baoding, and their migratory direction is mainly northeast and southwest.