Investigating the historic drought in the Yangtze River Basin in 2022–2023 by jointly using GRACE, land surface models, and drought index

The Yangtze River Basin. A historic drought occurred in the Yangtze River Basin (YRB) in 2022 and lasted to 2023. This study used the generalized three-cornered hat method to integrate multi-source GRACE and land surface model data and generated reliable terrestrial water storage (TWS) and soil moisture storage (SMS) data, based on which we investigated how TWS deficits evolved during the drought and how SMS and groundwater storage (GWS) responded to the drought. We also analyzed the meteorological cause of this drought from the perspective of land water balance. The TWS deficit emerged in July 2022, peaked in September at − 10.1 ± 1.0 cm, and ended in October 2023, lasting much longer than previously reported. The TWS, SMS, and GWS deficits all showed a distinct southwestward propagation pattern, different from the previously reported eastward movement. The GWS deficit (-9.3 cm) was much larger than the SMS deficit (-4.5 ± 2.5 cm) and peaked and ended 1–2 months later. Precipitation (P) dominated the TWS changes and as the drought intensified, the response of the SMS to P deficit weakened over time, while that of GWS strengthened. The substantial P deficit induced by the abnormal westward extension of the WPSH in July and August 2022 was responsible for the drought. • The terrestrial water storage (TWS) change during a historic drought in the Yangtze River Basin were investigated. • The TWS deficit showed a southwestward propagation with the peak deficit reaching − 10.1 ± 1.0 cm in September 2022. • Groundwater storage (GWS) deficit peaked and ended 1–2 months later than the soil moisture storage (SMS). • Response of SMS and GWS to precipitation weakened and strengthened over time as the drought intensified. • Abnormal westward extension of the WPSH in July and August 2022 was the main reason for the drought.