Abstract
Drought can cause severe agricultural economic losses and hinder social and economic development. To manage drought, the process of drought events needs to be described with the help of an effective drought indicator. As a comprehensive variable, soil moisture is an essential indicator for describing agricultural drought. In this work, the extreme drought events in southwest China were analysed by the Global Land Data Assimilation System (GLDAS) root zone soil moisture data set. To define the drought quantitatively, a Standardized Soil Moisture Drought Index (SSMI) was calculated using the soil moisture data, then used to get the duration, frequency, and severity of drought events in southwest China. The results showed that the frequency and intensity of drought in southwest China had an apparent upward trend before 2014 and an apparent downward trend since 2014. Moreover, there are apparent differences in the frequency and intensity of drought in various regions of southwest China. Yunnan Province is prone to spring drought events. Guangxi Province and Guizhou Province are prone to spring, autumn and winter droughts, and the intensity of autumn and winter droughts is significantly higher than that of spring droughts. The Sichuan-Chongqing border area is prone to summer drought. We found that the monthly variation of soil moisture in different provinces in southwest China is consistent, but the seasonal variation of drought is different. Meanwhile, the performance of the SSMI was compared to the commonly used drought indices, the Standardized Precipitation Evapotranspiration Index (SPEI) and the Palmer Drought Severity Index (PDSI). The results showed that the SSMI is more sensitive to drought than both SPEI and PDSI in southwest China. The results also demonstrate that GLDAS soil moisture data can be used to study drought at a small regional scale.
Highlights
Introduction published maps and institutional affilDrought is one of the most destructive and urgent natural disasters in the world [1], as it causes insufficient soil moisture and disrupts crop water balance and reduces yield.Among wholly natural disasters, drought is one of the most serious that endangers agriculture and animal husbandry production [2]
According to the statistical results, combined with the China Meteorological Administration’s statistical data, the southwest China’s statistical yearbook and the standardized soil moisture index (SSMI) classification standard [69], we found that when the SSMI was less than −0.5, the identified temporal and spatial variations of drought were consistent with the drought development process documented in the literature and government materials
SSMIdrought to obtain droug data for the Sichuan-Chongqing border area, we found that the drought events events were were co data for the Sichuan-Chongqing border area, we found that the drought concentrated in summerinand autumn
Summary
Introduction published maps and institutional affilDrought is one of the most destructive and urgent natural disasters in the world [1], as it causes insufficient soil moisture and disrupts crop water balance and reduces yield.Among wholly natural disasters, drought is one of the most serious that endangers agriculture and animal husbandry production [2]. Drought is one of the most destructive and urgent natural disasters in the world [1], as it causes insufficient soil moisture and disrupts crop water balance and reduces yield. Drought is one of the most serious that endangers agriculture and animal husbandry production [2]. In the context of global warming, the frequency and duration of drought events show an upward trend. From 1950 to 2008, the frequency of drought events in arid regions around the world increased by about 1.74% every ten years [3]. Facts prove that the impact of drought is extremely extensive and far-reaching [4]. Drought in 2012 caused severe agricultural disasters throughout North America, leading to a sharp increase in food prices [5].
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