Abstract:

Drought has significant impact on hydrological cycle, ecosystems, agricultural production and social life, thus requiring special attention. The characteristics of drought over a range of time scales were examined in Hubei Province in the past 50 years, using the standardized precipitation evapotranspiration index (SPEI) as an indicator of drought severity. The results showed that the frequency, duration, intensity and spatial extent of drought at different time scales were notably different, while the evolution characteristics of drought from different years were similar. At the time scale of 6 months or longer, wet periods were recognized in the early 60s, early 70s, 80s and early 90s in the 20th century, while since the late 90s especially the 21st the frequency of wet periods has decreased and of dry periods increased significantly. At the seasonal timescale, there was a drying trend for spring and autumn and minor wetting trend for summer and winter, among which the drying trend in autumn was statistically significant at 0.05 levels of significance. At the time scale of 1 month, the SPEI was so unstable that no trend or periodical characteristic was found. Over all the time scales, drought intensity has experienced an increasing tendency over the past 50 years, with the most severe droughts occurring in the last 20 years; drought spatial extent has changed in accordance with the variation of dry periods, but with a more distinct increase of large scale extreme drought in the last 10 years than in the past 40 years.