In-depth analysis of the characteristics of water and sedimentary changes at the confluence of the upper reaches of Weigan River and Heizi River is the prerequisite and basis for studying the future water and sedimentary situation in the Kizil Reservoir. This article analyzes the trend, mutation point and periodicity of the water and sedimentary sequence with multi-methods. The double cumulative curve method and the attenuation analysis method were used to analyze the impact of precipitation and human activities on runoff and sedimentary transport, and other influencing factors were qualitatively analyzed also. The results showed that: (1) In the past 60 years, Kizil Reservoir's runoff and sedimentary transport have shown an upward trend; the mutation point of the reservoirs' runoff was in 1994; the annual runoff had a periodicity of 7, 13, and 28 years; the annual sedimentary transport had a periodicity of 4, 12, and 26 years. (2) The impact of precipitation and human activities on runoff were 485.37% and −385.37%, respectively; the impact of precipitation on sedimentary transport was first high and then low, while the impact of human activities on sedimentary transport was first low and then high. Solar activities, ENSO, underlying surface changes and glacier snow melt also contributes to water-sediment changes to some extent.

为支撑乌东德水库实际调度排沙,建立乌东德水库干支流河道一维非恒定流水沙数学模型,利用蓄水后实测资料验证模型的可行性,继而模拟乌东德水库蓄水运用初期典型水沙过程的排沙特性。结果表明:7—8月份,乌东德水库在入库水量较大时均具有较强的排沙能力,水库具备利用大水排沙的有利条件;受入库沙量大幅减小影响,7—8月份乌东德水库变动回水区泥沙淤积量及占比均相对较小,水库具备开展优化调度的有利条件;汛期(7月份),来水较大时库水位>965 m后,变动回水区淤积占比开始逐步增加但淤积量很小,来水较小时变动回水区淤积规律类似,但对应临界库水位为960 m;蓄水期(8月份),来水较大时起蓄水位抬高对变动回水区淤积量及占比影响很小,来水较小时变动回水区淤积占比会随起蓄水位抬高而相应增大,但淤积量仍较小。研究成果可为水库优化调度提供参考。

Excessive sedimentation in sand-laden rivers significantly hinders the normal operation and overall effectiveness of reservoirs. This is observed particularly in plain-type sand-laden reservoirs where weak hydraulic conditions in the reservoir area contribute to sediment deposition. Water–sediment regulation is essential in reducing sedimentation and prolonging the lifespan of such reservoirs. Taking the plain-type reservoir of the primary stream of the Yellow River—Haibowan Reservoir as an example, based on a two-dimensional shallow water equation, a two-dimensional mathematical model of water and sediment in the reservoir area is established, the corresponding boundary conditions are improved, and the reliability of the model is verified. Under the premise of ensuring the flood control safety of the reservoir dam, considering the impact on the power generation of the reservoir and the downstream river, and maintaining the long-term large effective storage capacity of the reservoir as the basic principle, the water–sediment regulation scheme is proposed. A two-dimensional kinetic model of sediment transport and representative water–sediment series are employed to simulate the erosion and sedimentation processes in the reservoir under different schemes. The optimisation and comparison of multiple schemes reveal that the sediment-flushing scheme, which lowers the water level to 1072 m above sea level when the inflow discharge is 1500–2760 m3/s and inflow sediment concentration is 5–10 kg/m3, can yield an effective reservoir capacity of 97 million m3 and an average annual hydropower generation of 389.5 million kWh after 15 years of operation. This scheme outperforms the existing sediment-flushing scheme and is recommended as an optimised approach for water–sediment regulation in reservoirs. The results of this study provide technical support for the application of water–sediment regulation in the Haibowan Reservoir and may be useful in the exploration and management of water–sediment regulation for plain-type reservoirs on sand-laden rivers.

研究库区泥沙淤积情况对于水库的运行和管理十分重要,结合陆水水库建库前及近期库区地形,复核了陆水水库建库前库容曲线,采用断面法和栅格地形法分析了陆水水库库区的淤积时空分布特征,开展了淤积重点区域的河道演变分析,并从多个方面综合分析了库区淤积的影响。总体而言,陆水水库泥沙淤积总量不大,但局部库段淤积比较突出,对防洪、航运、灌溉、发电等功能发挥带来了不利影响,建议采取机械清淤、加强汛期排沙调度等措施,控制库区泥沙淤积,保持水库有效库容。研究成果可为水库相关管理工作提供参考。

[Objective] This study systematically examines the characteristics of sediment deposition and river evolution in Lushui Reservoir over 60 years since its construction and evaluates their comprehensive impacts. [Methods] Based on pre-construction (1959) 1∶10 000 topographic maps and recent (2018) 1∶5 000 maps, sediment volumes and stage-capacity curves were calculated using the cross-section method and 10 m × 10 m grid-based method (combined with Simpson’s 3/8 rule). [Results] The total deposition was 32.397 million m³, accounting for only 4.6% of the total storage below the design flood level, indicating overall light siltation. However, the spatial distribution was highly uneven—74% of the deposition was concentrated below the flood-limit water level, with the Hongshang-Shikeng downstream 11km reach becoming the core deposition zone, accounting for 51% of the total (local maximum deposition thickness up to 11.79 m), while the Hongshang-Langkou reach was likely in a scouring state due to unregulated sand mining and reduced sediment inflow. For channel evolution, the thalweg in the Hongshang-Shikeng reach rose on average 6.27 m, and the shoreline at the 45 m dead water level elevation shrank markedly; maximum thalweg migration reached 660 m (at the Lashupu widening), and the depositional pattern tended toward a deltaic form—with the Hongshang-Shikeng reach dominated by main-channel deposition, and sections above Hongshang mainly showing floodplain deposition. Deposition significantly impaired reservoir functions: (1) For flood control, 6.856 million m³ of flood-control capacity was lost (4.2% loss rate), and the cross-section area in the Hongshang-Shikeng reach was reduced by 26% on average (up to 54%), markedly lowering discharge capacity and raising the regulated flood levels under design floods. (2) For beneficial use, 17.193 million m³ of active storage lost (equal to an annual power loss of 842 000 kW·h), and 12.29 million m³ between the dead water level and flood-limit level was lost (8.1% of mean annual irrigation withdrawal). (3) For navigation, thalweg elevations were generally at or above the 45 m dead water level elevation, severely restricting navigation during low-flow periods. [Conclusion] Although the overall sedimentation rate of Lushui Reservoir is low, local deposition poses a significant threat to flood-control and navigation functions. Mechanical dredging in the key reach (Hongshang-Shikeng) and optimization of sediment-flushing schedules during the flood season are urgently needed to control sediment and maintain effective storage capacity. These findings provide a scientific basis for sediment management in long-operating reservoirs and for the development of “modern reservoir operation and management matrix” proposed by the Ministry of Water Resources.

海勃湾水库是黄河内蒙古段龙头水库，其排沙效果对水库运行及黄河内蒙古段泥沙淤积有着重要影响。水库排沙比是描述水库输沙特性的关键指标，排沙比越大，入库泥沙占水库淤积比例就越小。以海勃湾水库建成蓄水（2014年）至2021年实测资料为基础，分析水库排沙特征，并采用相关性分析探讨影响排沙比变化主要因素。结果表明：水库多年平均排沙比为19.35%，较设计值明显偏小，未产生理想排沙效果，淤积和排沙主要发生在汛期，大流量期间呈现“多来多排”的特点；排沙比变化主要受水沙条件和水库运行方式以及地形影响：排沙比与入库流量及入出库水沙协调性具有正相关关系，与坝前水位及滞洪时间具有负相关关系，水库地形上窄下宽、上陡下缓分布以及乌兰布和沙漠风沙入库对排沙比造成负面影响；汛期排沙比主要受滞洪时间影响。还建立了汛期排沙比经验计算式。

Haibowan Reservoir is a leading reservoir in the Inner Mongolia section of the Yellow River， and its sediment discharge effect has an important impact on the operation of the reservoir and the sediment deposition in the Inner Mongolia section of the Yellow River. The sediment discharge ratio of the reservoir is a key indicator to describe the sediment transport characteristics of the reservoir. The larger the sediment discharge ratio， the smaller the proportion of sediment in the reservoir. Based on the measured data of Haibowan Reservoir from 2014 to 2021， the characteristics of sediment discharge were analyzed， and the main factors affecting the change of sediment discharge ratio were discussed by correlation analysis. The results show that the annual average sediment discharge ratio of the reservoir is 19.35%， which is obviously smaller than the design value， and the ideal sediment discharge effect is not produced. The siltation and sediment discharge mainly occur in flood season， and the characteristics of "more coming and more discharging" are presented during large discharge period. The change of sediment discharge ratio is mainly affected by the water and sediment conditions， the operation mode of the reservoir and the topography. The sediment discharge ratio has a positive correlation with the inflow flow and the coordination of water and sediment in and out of the reservoir， and has a negative correlation with the water level in front of the dam and the flood detention time. The distribution of the reservoir topography is narrow at the top and wide at the bottom， steep at the top and slow at the bottom， and the inflow of wind-blown sand in the Ulanbu Desert have a negative impact on the sediment discharge ratio. The regression analysis shows that the sediment discharge ratio in flood season is mainly affected by the flood detention time and the empirical formula for sediment discharge ratio in flood season is established. The results can provide reference for the optimization of water and sediment control in Haibowan Reservoir.

为了揭示塔里木河干流典型蜿蜒型河流形态的形成及河道冲淤演变规律,基于遥感影像,用套绘的形式总结了塔里木河中游乌斯满—阿其克段近10 a河道边界的平面形态变化类型。结合实测大断面和水文资料,用河相关系分析了河道在不同时间下横断面的稳定性。结果表明:①塔里木河中游乌斯满—阿其克段河流平面几何形态演变主要分为4种单一变形(正偏、负偏、延伸、缩拢)以及4种组合变形(正偏+延伸、正偏+缩拢、负偏+延伸、负偏+缩拢)共8种形式,研究河段正偏+延伸变形占比最大。②提出描述河道平面的主要演变类型的形态参数偏移度与展宽度及其计算方法,发现影响偏移度的最主要因素是年径流量,其次是年输沙量和造床流量,洪水是影响展宽度的重要因素。③研究河段近年来河相系数增大,河床纵向趋于稳定,河床横向的稳定性沿程增大。研究成果对于塔里木河中游蜿蜒型河流防洪工程建设、河道整治具有重要的参考价值。

To reveal the formation and evolutionary patterns of typical meandering river morphology in the main stream of the Tarim River, this study used remote-sensing images and overlaying techniques to summarize the types of planform changes in the river boundaries of the middle reach of Tarim River from Wusiman to Aqike over the past decade. Moreover, integrating measured cross-sections and hydrological data, river regime analysis was employed to evaluate the stability of river cross-sections at different times. The results are as follows: 1) The planform geometric evolution of the middle reach from Wusiman to Aqike can be categorized into four single patterns (positive shift, negative shift, extension, and contraction) and four combined patterns (positive shift plus extension, positive shift plus contraction, negative shift plus extension, and negative shift plus contraction). Among them, the positive shift plus extension pattern is the most prevalent in the study reach. 2) Morphological parameters, namely the offset degree and widening degree, along with their calculation methods, were proposed to depict the main types of planform evolution in river channels. Annual discharge was found to be the primary factor influencing the offset degree, followed by the annual sediment transport and bedload discharge. Flood was identified as the key factor affecting the widening degree. 3) In recent years, the hydraulic geometric relation coefficient has increased, suggesting an enhanced longitudinal stability of the riverbed. Meanwhile, the transverse stability of the riverbed has also improved along the study reach. This research offers significant reference for flood control engineering and river channel regulation of meandering rivers in the middle reach of the Tarim River.

水库泥沙淤积是制约水库综合效益发挥的关键因素,采用传统工程清淤方式会引起底泥的再悬浮,导致底泥向水体释放营养盐,进而影响库区水环境。研究提出合理、切实可行的生态清淤方案,合理规避泥沙清淤所产生的水环境污染,是水库泥沙综合利用的前提。围绕新水沙情势下三峡水库淤积泥沙生态清淤需求,对比评估了现有水库清淤技术的特点、适用性及环保性,并结合三峡水库分段淤积特征,提出了适合三峡水库的环境友好型生态清淤技术。在此基础上,选取涪陵、忠县典型淤积河段作为典型区域,建立了二维水动力-悬浮泥沙数学模型,模拟该河段在不同清淤设备下的清淤效果,提出了典型河段生态清淤技术方案。研究成果为三峡水库库容保障及其长期有效使用和综合效益的可持续发挥提供科学依据。

水库泥沙淤积问题普遍存在于全球水库中,影响防洪、发电、航运、水资源利用等水库功能的正常发挥,尤其是坝前泥沙淤积,可能会堵塞电站进水口和泄流底孔,严重影响水库发电效益和泄洪安全。对于大型水库而言,坝前水深一般在100 m以上,高效安全地进行坝前深水清淤疏浚是有效控制水库泥沙淤积、保持水资源可持续利用的一种重要途径。研究了气动力式深水清淤技术,并在三峡水库坝前深水环境进行了清淤试验。研究结果表明气动力式清淤技术可在百米级的深水环境中安全高效运行,清淤成本可控。研究成果可为大型水库清淤疏浚提供技术参考。

Reservoir sedimentation is a worldwide problem which affects the normal functioning of flood control,power generation,shipping,and water resources utilization. In particular,sediment deposition in front of dam may block the water intake of hydropower station and bottom outlet,severely affecting the power generation efficiency and flood discharge safety. The water depth in front of the dam of large reservoirs is generally over 100 meters. Efficient and safe dredging is an important approach to effectively control sediment deposition and maintain sustainable development of water resources. In this paper,the aerodynamic deep-water dredging technology is studied and applied to the Three Gorges Reservoir. Application result manifests that aerodynamic dredging technology can be operated safely and efficiently in 100-meter deep water environment. The research results can be taken as a technical reference for the dredging of large reservoirs.

窎鱼嘴浅滩位于三峡水库变动回水区,水道具有弯、急、险的特点。为防止水道碍航,2018年汛期首次实施了维护性疏浚工程。通过对窎鱼嘴浅滩疏浚工作的设计方案、施工过程及时机、航道可持续性等方面进行分析和评价,综合评估年度疏浚维护效果并总结归纳维护性疏浚工作中存在的问题和不足。研究结果表明:2018年窎鱼嘴浅滩维护疏浚方案设计与河段河床演变及年度水沙输移规律相适应;疏浚时机选在汛后三峡蓄水河段水位抬高时,有效缓解了施工与通航的矛盾,并且利用汛后冲刷的规律达到了事半功倍的效果;但由于疏浚工程未改变引起河床演变的水沙条件及边界条件,维护疏浚工程难以保证航道的稳定性和可持续性。因此,建议继续加强河段水下地形观测,根据浅滩演变趋势 适时开展航道整治工程。该疏浚工程合理性、适应性的评估可为今后航道维护工作提供技术参考。

Diaoyuzui Shoal, located in a large curved passageway in the fluctuating backwater area of the Three Gorges Reservoir, was featured with curved and dangerous waterway and rapid current. A maintenance dredging project was first carried out in 2018. In this paper we analyzed the rationality, adaptability and sustainability of the dredging work based on summarizing the characteristics of shoals obstructing navigation, the dredging plan and the implementation process, etc., and then evaluated the effect of the dredging work and summarized its problems and shortcomings. Results demonstrated that the dredging design was well adaptive to riverbed evolution and annual water-sediment transport rules; the dredging was conducted when the water level of the Three Gorges storage reach rose, which not only alleviated the contradiction between construction and navigation, but also doubled the effect by taking the advantage of post-flood scouring. Nevertheless, the stability and sustainability of the channel are difficult to be maintained because the dredging project does not change the water and sediment conditions and boundary conditions that cause the riverbed evolution. Therefore, we suggested to strengthen the underwater terrain observation of the reach and carry out waterway regulation works in time according to the evolution trend of the shoal.