Dam‐Induced Alternations of Flow and Sediment Regimes in the Tibetan Plateau: An Example of the Yarlung Tsangpo River

Abstract Dams heavily regulate the natural hydrological regimes, impacting on riverine ecosystem and local communities. Yet, the impacts of dams on flow and sediment alterations in the alpine basins, such as the Yarlung Tsangpo River with its immense hydropower potential, remain largely understudied due to limited fine‐scale hydrological records. Here, we introduced a dynamic alteration index combined with wavelet analysis to evaluate the time‐varying alterations in flow and sediment regimes caused by dams in the basin from 1980 to 2020. Leveraging in‐situ daily observation data, we first capture both annual and intra‐annual trends by extending traditional indicators of hydrological alteration across three regulation scenarios: unregulated, tributary dam‐regulated, and both mainstem and tributary dam‐regulated. We then explore the spectral signatures of dam‐induced alterations to identify the most affected timescales and assess the impacts of dam configuration. Our analysis reveals that despite dam construction, river flow discharge increased slightly, with decreased low‐flow frequency and more common high‐flow frequency. Dam operations markedly altered sediment, disrupted sediment periodicities, and weakened flow‐sediment relationships. Specifically, sediment reduction was notable under dam regulation on both the mainstem and tributary, with a moderate alteration degree of 45.34%, particularly during the main flood and post‐flood seasons. Dominant sediment periodicities at annual and semi‐annual scales were nearly eliminated, while flow periodicities were preserved. Large flood events with high‐magnitude sediment were almost absent, and a figure‐eight hysteresis pattern indicated weakened sediment transport. These findings underscore the need for incorporating time‐varying hydrological dynamics into dam operation strategies to minimize negative impacts on sediment transport and aquatic ecosystems, providing essential insights for sustainable water resource management and future hydropower planning in alpine river basins.