Examining the 2022 drought event in the past and future discharge changes of the Upper Jialing River from a tree-ring perspective

Study Region: The Jialing River, distinguished as the largest tributary of the Yangtze River by watershed area Study Focus: In the context of a major drought in the Yangtze River Basin in 2022, this study examines the extent of low discharge in its largest tributary, the Jialing River, in that year from the long-term perspective of tree-ring, then explores possible relationships between discharge changes and large-scale ocean-atmosphere circulation, and finally identifies possible future discharge trends and the risk of extreme high or low discharge based on CMIP6 multi-model mean discharge data. New Hydrological Insights for the Region: Over the past 301 years, the low discharge value in 2022 exceeded the range of normal runoff fluctuations. Simultaneously, the average runoff values for the recent years, 2019–2022, reached historical lows. These discharge variations are primarily influenced by the Tropical Pacific Index and the North Atlantic Oscillation. Climate model projections indicate that the risk of the upper reaches of the Jialing River regularly experiencing extreme low discharge (similar to 2022) is trending downward, with a probability of ∼15% per year by 2100, while the risk of experiencing extreme high discharge is trending upward, with a probability of ∼28% per year by 2100. [Display omitted] •The 2022 low discharge value and the 2019-2022 average for the upper Jialing River exceed historical norms.•Discharge variations in the upper Jialing River are mainly influenced by the Tropical Pacific Index and the North Atlantic Oscillation.•By 2100, low discharge risk will decline, while high discharge risk will increase.