Japan Geoscience Union Meeting 2025

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[E] Oral

U (Union ) » Union

[U-02] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia

Wed. May 28, 2025 3:30 PM - 5:00 PM Exhibition Hall Special Setting (1) (Exhibition Hall 7&8, Makuhari Messe)

convener:Kaoru Kubota(Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology), Li Lo(Department of Geosciences, National Taiwan University), Yusuke Yokoyama(Atmosphere and Ocean Research Institute, University of Tokyo), Chuan-Chou Shen(National Taiwan University), Chairperson:Li Lo(Department of Geosciences, National Taiwan University), Kaoru Kubota(Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology), Chuan-Chou Shen(National Taiwan University), Yusuke Yokoyama(Atmosphere and Ocean Research Institute, University of Tokyo)

3:45 PM - 4:00 PM

[U02-08] Five-Century Monthly Streamflow Reconstruction of the Upper Brahmaputra River Reveals Unprecedented Recent Drought

*Wenzheng Nie1,2, Dunxian She2, Jun Xia2, Kanon Kino1 (1.University of Tokyo, 2.Wuhan University)

Keywords:Streamflow , Reconstruction , Brahmaputra River, Drought-Flood Abrupt Alternation, Monthly

Long-term streamflow records are essential for understanding changes in extreme hydrological events, especially drought and flood. Most existing long-term streamflow data are available at annual resolution, with monthly records being scarce, which limits the ability to reveal the seasonal variability of extreme hydrological events at monthly time scale. In this study, we developed a hierarchical weighting strategy (HWS) based on Mass Balance Regression (MBR) framework to reconstruct monthly streamflow data using tree-ring data. The upper Brahmaputra River (UBR) is chosen as a case study area, and the monthly streamflow data for the last five centuries (1500–2010) is reconstructed using a multi-species tree-ring network. The results showed that HWS significantly enhances the model skill of monthly streamflow reconstruction, with R2 improving by 37.3% compared to MBR. Further investigation using the reconstructed monthly streamflow data demonstrates that recent drought and pluvial events are highly unusual within the context of the last five centuries. Our study offers critical context and fundamental data for hydrological risk analysis and water resources management in a perspective of centuries of historical time scale.