Seven centuries of reconstructed Brahmaputra River discharge demonstrate underestimated high discharge and flood hazard frequency

The lower Brahmaputra River frequently floods during the monsoon season, causing significant damage. While climate models predict increased flood risk with warming, limited observational data hinders accurate assessment of natural variability. This study uses a seven-century tree-ring reconstruction of monsoon season discharge to show that the early instrumental period (1956–1986) was exceptionally dry. Flood hazard frequency, inferred from high discharge recurrence, is significantly underestimated by the instrumental record compared to past centuries and climate model projections. Relying solely on recent observations is insufficient for accurately characterizing flood risk in the region.

Mukund P. Rao, Edward R. Cook, Benjamin I. Cook, Rosanne D. D'Arrigo, Jonathan G. Palmer, Upmanu Lall, Connie A. Woodhouse, Brendan M. Buckley, Maria Uriarte, Daniel A. Bishop, Jun Jian, Peter J. Webster