Jim L. Best Amy E. East Lorenzo Rosa Qianhan Wu Yiyi Li Yu Qi Yunkai Li Dongfeng Li Ting Zhang 2026 <p><span>Climate warming and deglaciation are reshaping hydrological seasonality in cold–dry regions, threatening the long-term sustainability of agriculture, ecosystems and local communities. However, existing evidence is limited to runoff seasonality. Changing sediment-transport seasonality, a more sensitive component, is emerging as a substantial yet under-recognized threat to water infrastructure. Leveraging monthly observations from the upper Tarim River from the 1960s to 2000s, we show that a warmer and wetter climate has intensified sediment-transport seasonality, with a 43% increase in summer sediment fluxes. Over half of this amplification stems from more frequent extreme sediment transport, particularly events triggered by high sediment supply rather than high discharge. Supported by a state-of-the-art river change dataset, we show that enhanced sediment seasonality and extreme sediment transport have largely contributed to increased river mobility since 2000. Sediment-driven changes are pushing riverine processes towards greater unpredictability and pose growing threats to water infrastructure and water security in vulnerable cold–dry regions.</span></p> application/pdf 10.1038/s41893-026-01829-4 en Nature Water scarcity and infrastructure risk of amplified seasonal sediment transport article