近年来青藏高原暖湿化加剧了江河源区产汇流和侵蚀输沙过程的变化，而冰冻圈要素的变化使得该过程更加复杂。采用突变检验与IHA-RVA分析了沱沱河1986—2017年径流量和输沙量的变化程度，并基于PLS-PM结合其他环境因子对水沙通量的变化进行归因分析，结果表明：\mathrm{①}沱沱河水沙通量于1998年突变后显著增加，整体改变度分别为71.2%和67.5%，为高度改变，表明气候变化对河源区水沙通量的影响不亚于人类活动对中下游的影响。\mathrm{②}在气温与降水的驱动下，5~10月水沙通量显著增加，各月变化程度受到土壤、河道冻结程度以及植被变化的影响；年输沙量的变化由极端输沙事件的增加主导，降水量、冰川融水量和土壤解冻程度是主要影响因素。\mathrm{③}寒区水沙过程受降水、冰川、土壤冻融及植被的综合影响，有待对其进一步研究以保障青藏高原生态屏障建设与周边区域的可持续发展。

In recent decades, the warming and humidification of the Tibetan Plateau have aggravated changes in the runoff and sediment transport processes in the headwater area, and the uniqueness of the cryosphere has made them more complex. In this study, abruption tests and IHA-RVA were performed to assess the variation in the runoff and sediment flux of the Tuotuo River before and after the abrupt change from 1986 to 2017. PLS-PM attribution analysis was performed using environmental factors for runoff and sediment flux change attribution. The following three important conclusions were drawn: first, from 1986 to 2017, the runoff and sediment flux of the Tuotuo River changed abruptly around 1998, and the overall degrees of change were 71.2% and 67.5%, respectively; both were highly altered. This indicates that the impact of climate change on runoff and sediment flux in the headwater was not smaller than that of human activity downstream. Second, under the influence of temperature and precipitation, runoff and sediment fluxes from May to October increased significantly, and the degree of abruption was affected by the thawing degree of the soil, river channel, and vegetation coverage. The variation in the sediment flux was dominated by extreme sediment transport events, which were primarily caused by increased rainfall, ice melting, and soil thawing. Third, the runoff and sediment processes in cold regions are complex because of the combined influence of rainfall, glaciers, soil freeze-thaw, and vegetation. Therefore, it is necessary to further study the local region's ecological security and sustainable development downstream.