Influenced by climate change and human activities, especially the completion and operation of cascade reservoirs in the middle and lower reaches of Jinsha River since 2012, new changes have taken place in the water and sediment characteristics of the Three Gorges Reservoir (TGR) in recent years. In this paper, a one-dimensional unsteady water and sediment mathematical model of the main and tributary rivers of the TGR is established, and the main calculation parameters of the model are calibrated with the measured water and sediment data from January 1, 2008 to December 31, 2017. In view of the different combinations of inflow water and sediment that may occur in the TGR under the condition of new water and sediment, the long-term changes of sediment erosion and deposition and the balance of reservoir deposition in the TGR are studied using the model. The results show that: (1) Under the new conditions of water and sediment, the amount of sediment in the TGR accounts for only 14.8% and 35.8% of that in 1956–1990 and 2003–2012, respectively; (2) The variation process of water level, discharge and sediment concentration of each station along the route calculated by the model is basically consistent with the measured results, and the calculated values of total deposition amount and deposition distribution are also basically consistent with the measured results. The verification results of the model are in accordance with the measured values; (3) Under the water-sediment conditions during 1961–1970 and 1991–2000, the model predicted the estimates of 320 and 430 years for the TGR to reach a sedimentation balance, respectively. Under the new water-sediment conditions, it takes 560 years at most and 450 years at least to reach the sedimentation balance for the TGR, and the corresponding condition is the typical year with less water-less sediment and more water-more sediment, respectively. The research results of this paper can provide a new reference for the long-term safe operation and operation optimization of the TGR.

受气候变化和人类活动影响，特别是2012年以来金沙江中下游梯级水库建成投运，近年来三峡水库水沙特征发生了新的变化。 . 本文建立了三峡工程干流和支流的一维非稳态水沙数学模型，模型的主要计算参数用2008年1月1日至12月的实测水沙数据进行标定。 31, 2017. 针对三峡新水沙条件下可能出现的进水泥沙的不同组合，使用该模型研究了TGR中泥沙侵蚀沉积的长期变化以及水库沉积的平衡。结果表明：（1）在新的水沙条件下，TGR中泥沙量分别仅占1956-1990年和2003-2012年的14.8%和35.8%；(2) 模型计算得到的沿线各站点水位、流量、含沙量变化过程与实测结果基本一致，总沉积量和沉积分布计算值也与实测基本一致。结果。模型验证结果与实测值相符；(3) 1961-1970年和1991-2000年水沙条件下，该模型分别预测了 TGR 达到沉积平衡的估计时间为 320 年和 430 年。在新的水沙条件下，三峡大坝达到沉积平衡最多需要560年，最少需要450年，对应的条件分别是无水泥沙少和水沙多的典型年份。 . 本文的研究成果可为三轮发电机组的长期安全运行和运行优化提供新的参考。