Attribution of Extreme Drought Events and Associated Physical Drivers across Southwest China Using the Budyko Framework

Abstract

Drought is a meteorological phenomenon that negatively impacts agricultural production. In recent years, southwest China has frequently experienced agricultural droughts; these have significantly impacted the economy and the ecological environment. Although several studies have been conducted on agricultural droughts, few have examined the factors driving agricultural droughts from the perspective of water and energy balance. This study aimed to address this gap by utilizing the Standardized Soil Moisture Index (SSMI) and the Budyko model to investigate agricultural drought in southwest China. The study identified four areas in Southwest China with a high incidence of agricultural drought from 2000 to 2020. Yunnan and the Sichuan-Chongqing border regions experienced drought in 10% of the months during the study period, while Guangxi and Guizhou had around 8% of months with drought. The droughts in these regions exhibited distinct seasonal characteristics, with Yunnan experiencing significantly higher drought frequency than other periods from January to June, while Guizhou and other areas were prone to severe droughts in summer and autumn. The Budyko model is widely used as the mainstream international framework for studying regional water and energy balance. In this research, the Budyko model was applied to analyze the water and energy balance characteristics in several arid regions of southwest China using drought monitoring data. Results indicate that the water and energy balances in Yunnan and Sichuan-Chongqing are more moisture-constrained, whereas those in Guizhou and Guangxi are relatively stable, suggesting lower susceptibility to extreme droughts. Furthermore, during severe drought periods, evapotranspiration becomes a dominant component of the water cycle, while available water resources such as soil moisture decrease. After comparing the causes of drought and non-drought years, it was found that the average rainfall in southwest China is approximately 30% below normal during drought years, and the temperature is 1–2% higher than normal. These phenomena are most noticeable during the spring and winter months. Additionally, vegetation transpiration is about 10% greater than normal during dry years in Southwest China, and soil evaporation increases by about 5% during the summer and autumn months compared to normal conditions.

Distribution Characteristics of Drought Resistance and Disaster Reduction Capability and the Identification of Key Factors—A Case Study of a Typical Area in the Yun–Gui Plateau, China

“…The Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) from the United Nations reveals that the global average surface temperature increased by 1.09 • C during the period of 2011 to 2020 compared to that of the pre-industrial era of 1850 to 1900 [1,2]. In recent years, due to global warming and water resource shortages, the risk of compound high-temperature drought events may further increase [3][4][5]. The region around the Yun-Gui Plateau exhibits a subtropical monsoon climate and is characterized by the abundant distribution of limestone.…”

Contribution of Climate Change and Human Activities to Runoff and Sediment Discharge Changes Based on Budyko Theory and Water–Sediment Relationships during 1960–2019 in the Taohe River Basin, China

“…Li, C. et al [26] used the Budyko hypothesis to analyze the reasons for the decreasing trend of streamflow from 1960 to 2015 in the Yarlung Zangbo River. Sun, X. et al [27] analyzed the attribution of extreme drought events and the associated physical drivers in southwest China based on the Budyko framework. However, applications that combine qualitative and quantitative attribution analyses of runoff and sediment evolution are lacking.…”