Abstract:

Based on observation data from 29 national meteorological stations within and surrounding Poyang Lake basin from 1960 to 2020, we investigated the regional characteristics and evolution of meteorological droughts in the basin by calculating the Standardized Precipitation Evapotranspiration Index (SPEI) in association with the run theory.The findings indicate that the frequency of monthly meteorological droughts in the Poyang Lake basin ranged from 31.7% to 34.8%. Moreover, the spatial patterns of drought frequency varied significantly across different drought levels.SPEI of the Poyang Lake basin exhibited a slight downward trend in spring and autumn, with the affected area showing a marginal increase. Conversely, opposite trend was observed in summer and winter. Regarding regional characteristics, basin-wide (29.5% occurrence) and local droughts (23.4% occurrence) were predominant seasonal droughts in the Poyang Lake basin, whereas regional (10.7% occurrence) and partial regional droughts (5.7% occurrence) occured less frequently. The run theory revealed that 50 meteorological drought events have occurred in the past 61 years. The frequency of these events decreased notably with increasing drought duration, with the longest drought lasting up to 49 months. The duration, peak intensity, and total intensity of drought events exhibited pronounced inter-decadal fluctuations. A significant linear correlation existed between drought duration and total intensity, while a notable power function relationship was observed between drought duration and peak intensity. However, no significant correlation was found between drought duration and average intensity. These findings have clarified the regional characteristics and evolutionary processes of meteorological droughts in the Poyang Lake basin, thereby providing a scientific basis for assessing drought impacts and formulating effective prevention strategies.

Key words: meteorological drought, Standardized Precipitation Evapotranspiration Index, run theory, drought process, Poyang Lake basin