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Understanding of the spatio-temporal propagation of drought is a challenging issue as the hydro-climatic processes are inter-connected. Recent developments in network theory offer new avenues to study the propagation of drought. Three metrics that quantify the strength, dominant orientation and distance of droughts are employed to investigate the spatio-temporal propagation. The results show that (1) the network approach based on the event synchronization is a useful tool to study the propagation of drought; (2) The drought events occurring in the south of the study area are more likely to spread outward, and the drought events occurring in the midwestern regions are more likely to be affected by drought events in other regions; (3) The dominant position of drought transmission in the study area has obvious regional characteristics. The midwestern regions are more susceptible to the influence of drought events in the western regions, while other regions are more likely to spread drought events to the inside world. The findings of this paper could help researchers to initially understand the propagation of spatio-temporal droughts over Eastern China.

Reservoirs in the Daqing River mountainous area have always been an important source of replenishment for Baiyangdian Lake. With the development of water source economy and society, the reservoir’s ecological water replenishment potential for Baiyangdian Lake will undergo great changes. This article first analyzes the current situation of ecological water replenishment in Baiyangdian Lake. On this basis, the ecological water supply potential of the upstream reservoir to Baiyangdian Lake in the future was calculated. The results of the study show that from 2001 to 2018, the amount of water entering the upper reaches of the reservoir showed an overall upward trend, and the upward trend of runoff from the Xidayang Reservoir was the most obvious. Under different incoming water conditions, the ecological water supply potential of the upstream reservoir to Baiyangdian varies greatly. It can reach 320 million m3 in a wet year and only 50 million m3 in a dry year. In the continuous dry years, the average multi-year water supply potential of the reservoirs to the river and Baiyangdian Lake is about 146 million m3. The results of this paper can be used as a reference for Baiyangdian Lake’s ecological water replenishment scheduling