水库修建后下泄水流的含沙量大幅减少,泥沙沿程恢复引起下游河道冲刷调整,可能会给下游防洪、水资源利用及水生态环境等方面带来一定影响,同时该研究也是河流泥沙动力学的难点之一。从泥沙恢复特征和理论研究2个方面归纳总结了现有研究成果,得到以下认识:①不同水库下游河道泥沙恢复过程呈现较大差异性,对下游河道泥沙恢复规律认识也不尽相同,其中粗、细泥沙沿程恢复过程中是否存在相互交换仍缺乏一致认可的观点;②泥沙恢复饱和系数的经验计算结果与实际资料具有较高的吻合度,但受限于实测资料的差异性,经验公式的适用范围受限,且其物理意义、计算表达式及取值等尚未形成统一认识;③在泥沙恢复饱和系数重要影响因素的研究中,关于平衡输沙含沙量垂线分布的成果较为丰富,其主要难点集中于次饱和水流条件下泥沙浓度的垂线分布,一些关键参数如非饱和系数c、加权系数$\mu $、底部含沙量S_b等计算取值仍未得到较好的解决。鉴于当前研究不足,未来可从以下方面推进研究:①加强原型观测,尤其应强化含沙量垂线分布的专题观测,利用人工智能等先进技术对观测数据进行整合与分析,为后续深入研究提供数据支撑;②利用先进精密的测量仪器,深入开展相关水槽试验,为理论研究提供精确、全面且系统的观测资料,推动相关理论关键参数的突破;③结合实测资料分析及水槽试验研究,深入研究泥沙沿程恢复的基础理论,并深化次饱和水流含沙量垂线分布等方向的研究。

[Objective] After the construction of reservoirs, the sediment concentration in discharge flow has significantly decreased. The along-reach recovery of sediment leads to scour adjustments in the downstream river, potentially impacts downstream flood control, water resource utilization, and aquatic ecological environments. Meanwhile, this topic remains one of the key challenges in river sediment dynamics. [Methods] This paper summarizes the existing research results in the characteristics of sediment recovery and theoretical research, analyzes the deficiencies in the current research, and preliminarily discusses the future research directions. [Results] (1) The sediment recovery processes and patterns in the downstream reaches of different reservoirs show significant differences.The recovery varies among different grain-size groups of sediment.Factors such as riverbed composition, inflow of water and sediment from lakes and tributaries all have an impact on the recovery rates of different grain-size groups of sediment. However, there is no consensus on whether there is an exchange between coarse and fine sediment during the along-reach recovery process. (2) Scholars derive the sediment recovery saturation coefficient through back-calculation based on measured data or constructed empirical formulas. The calculation results show a high degree of consistency with actual data. However, due to the differences in measured data, the applicable scope of the empirical formulas is limited. There is not yet a unified understanding on its physical meaning, calculation formulations, and value selection. Among them, some parameters in the expression derived by Han Qiwei are relatively complex, and some key parameters still rely on empirical formulas or empirical values, which to a certain extent restricts its wide application in mathematical models. (3) Abundant achievements have been made in key influencing factors of the sediment recovery saturation coefficient.Theoretical formulas and improved formulas for the vertical distribution of equilibrium sediment transport concentration. Basically meet the current requirements of calculation accuracy. The main difficulty of the research lies in the vertical distribution of sediment concentration under the unsaturated flow condition. Although scholars such as Han Qiwei have proposed effective methods, the calculation and value selection of some key parameters, such as the unsaturated coefficient c, the weight coefficient μ, and the bottom sediment concentration S_b, have not yet been well resolved.[Conclusion] Future research can be advanced in the following aspects: 1) strengthen prototype observations, particularly targeted observations of the vertical distribution of sediment concentration, and utilize advanced technologies such as artificial intelligence to integrate and analyze observational data; 2) use advanced and precise measuring instruments to conduct in-depth flume experiments, provide accurate, comprehensive and systematic observational data for theoretical research;3) combine the analysis of measured data and the results of flume experiments for research on the basic theory of along-reach sediment recovery,and deepen research on directions such as the vertical distribution of sediment concentration in unsaturated flows.