Abstract:

To provide a reference for addressing the adverse effects of drought heat wave compound events under climate change, promoting agricultural development, protecting the ecological environment and rationally using water resources, an analysis was conducted using daily meteorological data from 80 national meteorological stations spanning the period from 1971 to 2023. This study aimed to investigate the temporal and spatial variability characteristics of drought heat wave compound events within the province. Additionally, the correlation between these compound events and agricultural drought was analyzed and evaluated. The results indicated that: (1) from 1971 to 2023, the cumulative drought days, times of heat waves and drought heat waves compound events at 80 stations in Guizhou exhibited increasing trends following abrupt changes in 2019, 2008 and 2020, respectively. In addition, the oscillation strength of these events intensified over time, with notable period variations of approximately 17 and 11 years. Notably, times of heat waves fluctuated significantly at a rate of 11 per decade (P<0.01), whereas drought days and times of drought heat wave compound events did not display significant trend changes. (2) From 1971 to 2023, the distribution of drought days, times of heat waves and drought heat waves compound events in Guizhou exhibited similar west-to-east characteristics, with a notable increase in the number of drought heat waves compound event from west to south. Specifically, 12.5% of the stations observed a statistically significant increase in drought days (P<0.05), 26.3% of the stations experienced a significant rise in times of heat waves (P<0.05), and 5.0% of the stations reported a significant increase in times of drought heat waves compound events (P<0.05). (3) The occurrence of times of drought heat waves compound events in Guizhou from 1971 to 2023 was positively affected by the same intensity of drought days and times of heat waves.The spatial distribution of these events followed a southwest-to-northeast pattern and an elevation gradient from high to low. The risks associated with these three disasters (drought, heat waves and their composite events) increased significantly. (4) From 2010 to 2022, the drought-affected crop area in Guizhou exhibited a significant positive correlation with the drought days and times of heat waves recorded at 80 stations within the province (P<0.05). Furthermore, an extremely significant positive correlation was observed between the drought-affected crop area and times of drought heat waves compound events (P < 0.01). It is important to note that the number of drought heat wave compound event had a more profound impact on agricultural drought compared to the drought days or heat waves number alone.

Key words: Guizhou, MCI drought index, Heat wave, Drought heat wave compound event, Agricultural drought