Temporal-spatial evolution of the hydrologic drought characteristics of the karst drainage basins in South China

- We systematically analyzed the spatial-temporal evolution pattern of hydrologic droughts.
- From 1970s to 2010s, hydrologic droughts exhibited “an upward trend after a previous decline.”.
- The spatial-temporal evolution pattern of occurrence frequency in the karst drainage basins in Southern China is consistent with hydrologic drought intensity.
- The karst drainage basins in Southern China experienced extremely complex variability of hydrologic droughts from 1970s to 2010s.

Hydrologic drought, as a typical natural phenomenon in the context of global climate change, is the extension and development of meteorological and agricultural droughts, and it is an eventual and extreme drought. This study selects 55 hydrological control basins in Southern China as research areas. The study analyzes features, such as intensity and occurrence frequency of hydrologic droughts, and explores the spatial-temporal evolution patterns in the karst drainage basins in Southern China by virtue of Streamflow Drought Index. Results show that (1) the general hydrologic droughts from 1970s to 2010s exhibited “an upward trend after having experienced a previous decline” in the karst drainage basins in Southern China; the trend was mainly represented by the gradual alleviation of hydrologic droughts from 1970s to 1990s and the gradual aggravation from 2000s to 2010s. (2) The spatial-temporal evolution pattern of occurrence frequency in the karst drainage basins in Southern China was consistent with the intensity of hydrologic droughts. The periods of 1970s and 2010s exhibited the highest occurrence frequency. (3) The karst drainage basins in Southern China experienced extremely complex variability of hydrologic droughts from 1970s to 2010s. Drought intensity and occurrence frequency significantly vary for different types of hydrology.