Abstract:

The frequent and complex drought disasters in Dali Prefecture in recent years have posed a long-term threat to the sustainable development of agriculture. Studying the occurrence patterns and development trends of droughts in Dali Prefecture can provide a scientific basis for drought prevention and monitoring. Using the monthly precipitation data from 12 meteorological stations in Dali Prefecture, the standardized precipitation index (SPI) values at different time scales from 1965 to 2024 were calculated for each station. The spatiotemporal variation characteristics of droughts at annual and seasonal time scales in Dali Prefecture were analyzed based on three indicators: drought frequency, drought intensity, and drought station proportion. The results show that: (1) the average annual drought frequency in Dali Prefecture is 32.22%, with relatively higher frequencies of severe and extreme droughts in the northwestern, central, and southeastern regions. The average seasonal drought frequency ranges from 29.17% to 30.28%, with relatively higher frequencies of spring, autumn, and winter droughts, and slightly lower summer drought frequency. (2) From the view of drought level, droughts at both annual and seasonal scales are dominated by light and moderate droughts. The intensities of annual, summer, and autumn droughts show an upward trend, while the intensities of spring and winter droughts show a downward trend. (3) From the aspect of drought range, the scopes of droughts at both annual and seasonal scales are mainly characterized by localized and region-wide droughts. The scopes of annual, summer, and autumn droughts show an upward trend, while the scopes of spring and winter droughts show a downward trend. (4) Overall, both the drought intensity and the drought station proportion in Dali Prefecture show an upward trend, indicating that droughts are developing towards higher intensity and larger scope. In recent years, the proportion of extreme droughts such as severe and extreme droughts has increased, and the impact scope and intensity of droughts have also shown an increasing trend. The research results can provide a scientific basis for drought monitoring and disaster prevention and mitigation measures in Dali Prefecture.

Key words: Dali Prefecture, meteorological drought, standardized precipitation index, drought frequency, drought intensity