National-Scale Variation and Propagation Characteristics of Meteorological, Agricultural, and Hydrological Droughts in China

Abstract

The regional and national scales variation and propagation characteristics of different types of droughts are critical for improving drought resilience, while information is limited in China. The objective of this research was to investigate the evolution and propagation characteristics of three types of droughts using standardized indices at multi-timescales in different sub-regions of China. The indices included Standardized Precipitation/Soil Moisture/Runoff Index (SPI/SSI/SRI) using the optimal probability density function, representing meteorological, agricultural, and hydrological droughts based on precipitation, soil water storage, and baseflow-groundwater runoff, respectively. Wavelet analysis was used to reveal their periodical characteristics. Modified Mann-Kendall trend test was used to compare the trend among drought indices. Correlation coefficients between SPI and SSI/SRI were calculated to identify the time-lags of SPI with SSI and SRI. In general, droughts indicated by SPI agreed well with the historical drought events at different sub-regions. The main periods of SSI were closer to SPI than SRI, indicating stronger connections of agricultural drought with meteorological drought. A weaker connection between meteorological and agricultural/hydrological droughts at shorter timescales was observed in northwestern arid and semi-arid regions. The propagation from meteorological to agricultural or hydrological droughts were well denoted by the lagged time (months) from SPI to SSI or SRI at a timescale ranged from 0 (mostly located in south China) to 5 months (mostly located in northeastern China) for 1-, 3-, 6-, 12-, or 24-month timescale; this was a new finding for China. The methods of wavelet combining trend test and Pearson coefficient showed meaningful power for revealing the drought propagation characteristics and the obtained results can be a good reference for other regions of the world since this study compared different climate zones from arid to humid conditions. The study provides crucial information and guidance to develop drought management strategies at regional to national scale and their critical time of action.

Investigating the Spatio-Temporal Variation of Soil Moisture and Agricultural Drought towards Supporting Water Resources Management in the Red River Basin of Vietnam

“…The mean air temperature in the wet season was much higher than those in the dry season and transitional months, subsequently leading to the larger evapotranspiration in the wet season than those in the dry season and transitional months. Both precipitation and air temperature had significant impacts on the soil moisture changes in the northeast and northwest regions, which was reported in other studies [6,9,13,17,[23][24][25][26][27]. However, the impact of temperature on soil moisture appeared to be larger than that of precipitation in the two regions, which was also reported in the previous study [28].…”

Identification of Regional Drought Processes in North China Using MCI Analysis

“…According to the research results of Yao. N. et al, (2020) [44], the recent meteorological drought (SPI) in the south and north of China has a good correlation with agricultural drought (SSI) and hydrological drought (SRI). Compared with this, the meteorological drought comprehensive index (MCI) used in this study comprehensively considered this relationship, which is reflected in the coefficients a, b, c and d, including the distinction between the south and the north.…”

Characteristics of Agricultural Droughts and Spatial Stratified Heterogeneity and Dependence of Dominant Factors in Inner Mongolia Autonomous Region, China

“…The whole subregion suffered from droughts in the springs of 2000, 2012, 2013, and 2018; the summers of 2001, From the perspective of land-atmosphere feedback, there is a close relationship between meteorological and agricultural droughts. Meteorological droughts are the cause of, and occur earlier than, agricultural droughts [21]. On this basis, by comparing SPEI-1 with the standardized SMAPI of the Inner Mongolia Autonomous Region, it is found that they are similar to a great extent, reflecting the same drought change trend, which can well characterize droughts in this region.…”