Flash droughts cause rapid depletion in root-zone soil moisture and severely affect crop health and irrigation water demands. However, their occurrence and impacts in the current and future climate in India remain unknown. Here we use observations and model simulations from the large ensemble of Community Earth System Model to quantify the risk of flash droughts in India. Root-zone soil moisture simulations conducted using Variable Infiltration Capacity model show that flash droughts predominantly occur during the summer monsoon season (June–September) and driven by the intraseasonal variability of monsoon rainfall. Positive temperature anomalies during the monsoon break rapidly deplete soil moisture, which is further exacerbated by the land-atmospheric feedback. The worst flash drought in the observed (1951–2016) climate occurred in 1979, affecting more than 40% of the country. The frequency of concurrent hot and dry extremes is projected to rise by about five-fold, causing approximately seven-fold increase in flash droughts like 1979 by the end of the 21st century. The increased risk of flash droughts in the future is attributed to intraseasonal variability of the summer monsoon rainfall and anthropogenic warming, which can have deleterious implications for crop production, irrigation demands, and groundwater abstraction in India.

旱灾造成根区土壤水分迅速枯竭，严重影响作物健康和灌溉需水。但是，它们在印度当前和未来气候中的发生和影响仍然未知。在这里，我们使用大型社区地球系统模型的观测和模型模拟来量化印度山洪暴发的风险。使用可变入渗能力模型进行的根区土壤湿度模拟显示，山旱主要发生在夏季季风季节（6月至9月），并且受到季风降雨季节内变化的驱动。季风爆发期间的正温度异常迅速耗尽了土壤水分，陆地-大气反馈进一步加剧了土壤水分。在观测到的（1951-2016）气候中，最严重的山洪干旱发生在1979年，影响超过40％的国家。预计同时发生的高温和干旱极端事件的频率将增加大约五倍，到21世纪末，像1979年一样，山洪暴发将使干旱增加大约七倍。未来山洪暴发的风险增加归因于夏季季风降雨和人为变暖的季节内变化，这可能对印度的农作物产量，灌溉需求和地下水抽取产生有害影响。