Yangtze River
Current Status and Recent Trends
- The Yangtze River Basin (YRB) has experienced significant subsoil moisture deficits in recent years, with the most extreme event occurring during the summer and autumn of 2022. During this period, soil moisture levels dropped below 5%, marking the most severe regional drought since at least 2000 and surpassing the severity of the 2019 drought[1].
- In autumn 2022, prolonged drought led to a dramatic reduction in soil moisture throughout the basin, with the middle and lower reaches being especially affected[2][1].
- Drought indices incorporating soil moisture, such as the PDSI_China and SC-PDSI, confirmed extreme drought severity in the Yangtze River Basin during this time, reflecting the compound effects of precipitation deficits and high temperatures[3].
Drivers and Patterns
- The primary drivers of subsoil moisture depletion in the YRB are prolonged precipitation deficits, persistent high temperatures, and increased atmospheric water demand, which together enhance evapotranspiration and accelerate soil drying[3][1].
- The middle and lower Yangtze River Basin are particularly sensitive to precipitation variability, with cropland areas showing a more pronounced downward trend in soil moisture due to water resource management practices[4].
- Despite these severe droughts, long-term data (over the past four decades) show only minimal increases in average soil moisture in the middle and lower YRB (on the order of 6.61 × 10⁻⁴ and 5.50 × 10⁻⁴ m³/m³ per decade), indicating that recent extreme events represent significant anomalies rather than a persistent trend[4].
Soil Moisture Regimes and Critical Thresholds
- The critical soil moisture (CSM) threshold—below which ecosystems become water-limited—varies by land cover and soil type, but in the YRB, forested regions typically have higher CSM values (e.g., around 0.18 m³/m³ at 10 cm depth), while cropland and grassland may experience water limitation at lower soil moisture levels[5].
- Spatial patterns show that southern and eastern China, including the YRB, generally have higher CSM values, but are still vulnerable to rapid depletion during compound drought–heatwave events[5][3].
Impacts and Outlook
- The 2022 drought caused widespread negative impacts on vegetation, agriculture, and hydrological systems, with vegetation in the middle and lower YRB showing high sensitivity to soil moisture deficits[6][2].
- The frequency and severity of autumn droughts in the YRB are projected to increase in future years, raising concerns about long-term water security and ecosystem resilience[6].
- As of early 2025, while some recovery has occurred, subsoil moisture levels remain below average in many parts of the basin, and the region remains at risk for further drought if precipitation deficits persist[4][3].
Summary Table: Yangtze River Basin Subsoil Moisture (Recent Years)
Period | Subsoil Moisture Status | Notable Features/Impacts |
Summer–Autumn 2022 | Plummeted below 5% | Most severe drought since 2000; widespread vegetation stress[1][2] |
2023–2025 | Below average, slow recovery | Some improvement, but deficits remain in cropland and lower basin[4][3] |
Long-term trend | Minimal increase overall | Extreme events represent significant anomalies[4] |
Key Takeaways
- The Yangtze River Basin remains highly vulnerable to subsoil moisture deficits, with recent years marked by record-breaking drought and slow recovery.
- Precipitation is the dominant factor controlling subsoil moisture in the basin, and future projections indicate an increased risk of severe droughts, especially in autumn.
- Ongoing monitoring and adaptive management are essential to mitigate the impacts of soil moisture deficits on agriculture, ecosystems, and water resources.
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- https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024EA003972
- https://www.tandfonline.com/doi/full/10.1080/11956860.2025.2494388?src=exp-la
- https://essd.copernicus.org/articles/17/837/2025/essd-17-837-2025.pdf
- https://www.mdpi.com/2072-4292/17/6/1000
- https://hess.copernicus.org/articles/29/1241/2025/hess-29-1241-2025.pdf
- https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2025.1534674/full
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