Spatiotemporal characteristics of extreme hydrometeorological events and its potential influencing factors in the Huaihe River Basin, China

The Huaihe River Basin (HRB) is located in the north-south climate transition zone of China and is highly susceptible to climate change. Analysis of the evolution pattern and potential causes of extreme hydrometeorological events is of great significance for flood prevention, mitigation and water resource planning in the basin. Based on the measured meteorological data in the HRB for 1963–2018, statistical analysis methods were used to test variations on extreme hydrometeorological events (precipitation and drought). Possible effects of global warming, atmospheric circulation patterns and sunspots on the spatiotemporal variability of hydrological events were also explored, effectively identifying the common influencing factors of extreme precipitation and drought events. The results show that (1) Extreme hydrometeorological events in the upper reaches are serious, but extreme precipitation tends to slow with time; the increase in extreme precipitation indices in the middle reaches deserves attention, while drought conditions are relatively mild; the drought trend in the lower reaches is significant, and extreme precipitation has improved. (2) Each inactive image for different periods is loaded onto the canvas, and a dynamic graph is used to display the temporal and spatial evolution pattern of extreme hydrometeorological events. (3) Global mean near-surface temperature anomalies (GTEM) are positively correlated with most extreme precipitation indices but negatively correlated with drought indices. The increase in the number of sunspots eased extreme precipitation and worsened drought.