Distribution characteristics of drought and flood hazards in northern China against the background of climate warming

The spatiotemporal characteristics of temperature and precipitation are complex in northern China. It is an area of frequent droughts and floods. Climate warming has exacerbated the complexity of drought and flood incidences. Based on the actual observation data from meteorological stations in northern China, this study analyzed the hazard characteristics of drought and flood disasters and revealed the distribution pattern and variation characteristics of high-hazard areas of drought and flood disasters before and after an abrupt temperature jump in 1995. The results showed that, from 1970 to 2021, the annual average temperature in the study area showed a significant increasing trend (0.34 °C/10 years), and the summer monsoon-transition areas showed a drying trend in spring and summer and a wetting trend in autumn and winter, with the summer monsoon-affected areas mainly getting wetter. The high-drought-hazard area is primarily located in the west and northeast of the summer monsoon-transition areas and the northeast of the summer monsoon-affected areas. The high-flood-hazard area is mainly located in the northwest and south of the summer monsoon-affected areas. The high-hazard area with overlapping drought and floods is primarily located in the northeast of the study area. After a major abrupt temperature jump in 1995, the normal probability distribution curve of the intensity of drought and floods at different levels generally moved to the dry side, the probability of occurrence of extreme drought and extreme flood events increased, the scale of high-hazard areas caused by drought and floods was significantly expanded, the high-hazard areas caused by drought and flood were transferred to the monsoon edge area, and the high-flood-hazard areas were transferred from the middle to the north to the south. The scale of the transition from low-hazard areas caused by drought and flood to high-hazard areas and from high-flood-hazard areas to high-drought-hazard areas was more extensive. The research results provided important scientific guidance for the formulation of drought and flood disaster prevention planning and agricultural production development strategies in China.