水利水电技术（中英文）

资料分析表明,宁蒙黄河冰凌灾害频繁的被动局面是由于主槽萎缩、卡冰结坝所致;而洪灾与用水安全问题则是河势变化无常和多沙支流突发性洪水淤堵干流形成"沙坝"引起的。为有效恢复宁蒙河段的行洪排沙功能,实现河道减淤、恢复和维持河道中水河槽、保障防洪(凌)安全的宁蒙黄河治理目标,从产沙、输沙、调控机理三个角度出发,分析了各因素对宁蒙黄河河床演变特征的影响。就产沙而言,通过产沙地貌分区、遥感影像分析和流域水系分区相结合的方法确定黄河上游不同沙源区的分布。基于提出的风蚀输沙通量计算方法及风沙入河估算方法,并结合区域风速与植被覆盖率实测数据,发现近30 a风速下降、区域植被覆盖率上升是风沙侵蚀量与入黄风沙量逐渐减少的原因。分析宁蒙河段日均风速、日降雨量和已有侵蚀观测资料,发现宁蒙地区的风水两相侵蚀主要体现为风蚀与水蚀交错存在及其交互促进,风力侵蚀主要发生在3—5月,水力侵蚀则集中在7—9月。现场观测与黄土降雨侵蚀模型试验则表明,重力侵蚀在黄土高原的整个侵蚀过程中占有重要的份额,暴雨形成的径流是黄土遭到侵蚀的主要外营力,也是激发和加剧重力侵蚀发展的重要影响因子。总体来看,宁蒙黄河的流域产沙具有典型的风-水-重力多营力交互特点,在比尺模型与野外观测揭示的流域径流汇集过程、沟道水流与河床自适应以及非平衡输沙机理基础上,构建了复杂地貌形态的小流域产流产沙动力学模型,成功模拟了不同植被特征和分布状况对流域产流产沙的影响,并得出了植被的减水减沙效果与延滞径流洪峰的作用同郁闭度呈正相关关系,陡坡区域植被对径流洪峰的延滞作用大于缓坡区域的结论。就输沙而言,以泥沙起动、推移质输沙与河床均衡调整等基础理论为基础,提出了水沙两相流数值模拟方法与冲积河流全沙运动模型相似条件。数值计算与模型试验表明,龙羊峡、刘家峡水库联合运用改变径流分配是导致宁蒙河道淤积萎缩的主因,协调水沙关系是修复黄河行洪排沙功能的有效途径。并分析确定了宁蒙黄河河道水沙调控阈值和多沙支流入汇口干流防淤堵的流量阈值,即宁蒙黄河临界调控流量为2 000～2 500 m³/s,临界含沙量5.4～10.5 kg/m³,调控时间为15～20 d,证实了通过协调水沙关系可修复和维持宁蒙黄河行洪排沙功能;防止多沙支流入汇堵河的黄河流量阈值为2 500 m³/s,治理淤堵沙坝配合"挖引疏浚"有效冲刷的干流阈值流量为3 000 m³/s。从各河段模型试验给出的来沙系数阈值沿程减小的变化趋势看,在内蒙古河段现状河床边界条件下,全线冲刷要求的流量至少为2 600 m³/s,表明黑山峡工程必须预留充足的水沙调控库容。就宏观调控而言,针对流域下垫面条件多样、入黄泥沙沙源众多、河道输沙受水库调度影响显著等特点,以干流水库群为调节器,以径流泥沙为调节对象,采用模块化开发方法集成了风-水-重力侵蚀模型、河道输沙模型、冰情预报模型于水库联调模型上,构建了可进行大范围、高精度的水沙过程模拟预报的宁蒙黄河区域数字流域模型平台,并成功在下河沿—石嘴山河段进行了调试和应用。此外,针对宁蒙黄河河型复杂、凌汛期易卡冰结坝、夏季多沙支流突发性洪水易堵干流形成"沙坝"等河情状况,提出了"水沙调控、支流拦沙、堤外放淤"的处治模式。在稳定性分汊河段、大型支流入汇段、受沙卵石河床组成限制的河段,则指出不宜强行套用微弯型治理方案,而可采用"工程导送(简称为‘导’)、塞支强干(简称为‘塞’)、挖引疏浚(简称为‘挖’)"方针,亦即"导、塞、挖并举"的对策。建设黑山峡水库、南水北调西线工程等是宁蒙河段长远治理的根本对策,通过增加河道内汛期水量和调水调沙,恢复并维持中水河槽,提供防凌库容,才能彻底解决宁蒙河段凌洪灾害,并得出建立黄河上游沙源固定、支流泥沙阻截、干流泥沙输导与堤外淤沙处置的"固-阻-输-置"综合防治体系,是目前可行的治理对策的结论。

The analysis shows the passive situation of frequent ice disasters in Ningmeng Yellow River is caused by main channel shrinkage and glaciation dam formation. Meanwhile, the flood damage and water security problem are generally triggered by capricious river regime and sand dam induced by sudden flood of sandy tributaries entering main stream. Therefore, in order to effectively restore the flood and sediment releasing capacity of the Ningmeng main channel, realizing the goal of sedimentation reduction, restoration and maintenance of river channel for medium flood, and flood control safety, herein the influence of various factors on the evolution characteristics of Ningmeng Yellow River was analyzed from the perspectives of sediment production, sediment transport and control mechanism.In term of sediment production, the distribution of different sediment source areas in the upper reaches of Yellow River was determined through the combination of sediment-producing geomorphology division, remote sensing image analysis and watershed water system division. Based on the proposed calculation method of wind-erosion sediment flux and inflow amount of wind sediment, combined with the measured data of regional wind speed and vegetation coverage, it was found that the decrease of wind speed and the increase of regional vegetation coverage in recent 30 years were the main reasons for the gradual decrease of wind-sediment erosion and blown into channel. In addition, the analysis results of observed average daily wind speed, daily rainfall and erosion in Ningmeng reach show that the geomantic two-phase erosion in Ningmeng area is mainly reflected in the alternating existence and mutual promotion of wind erosion and water erosion. Wind erosion mainly occurred from March to May, while water erosion usually relatively concentrated from July to September. Field observation and model test of loess rainfall erosion show that gravity erosion occupies a crucial part in the whole erosion process of loess plateau, and runoff formed by rainstorm is the main external force of loess erosion, as well as an essential influencing factor to stimulate and intensify the development of gravity erosion. In general, sediment production in the Yellow River basin of Ningmeng reach presents the typical characteristics of wind-water-gravity multi-battalion interaction. On basis of the revealed runoff gathering process, channel flow and riverbed adaptation, and non-equilibrium sediment transport mechanism through physical model and field observation, the dynamic model of sediment yield and runoff in small watershed with complex landform was constructed, and the effects of different vegetation characteristics and distribution were successfully simulated. The simulation results indicate that the effect of vegetation on water and sediment reduction and the effect of delayed runoff and flood peak are positively correlated with the canopy density, and the effect of vegetation on delayed runoff and flood peak in steep slope area is greater than that in gentle slope area.In term of sediment transport, based on the basic theories of incipient sediment motion, bed load transport and riverbed equalization adjustment, both the numerical simulation method of water and sediment two-phase flow and the similarity law of physical model for alluvial river are proposed. Numerical calculation and physical test results show that, the altered runoff distribution induced by joint operation of Longyangxia Reservoir and Liujiaxia reservoir, is the main reason causes the severe shrinkage in main channel of Ningmeng reach. Coordinating the relationship between water and sediment is an effective way to repair the function of flood and sediment transport capacity in the Ningmeng Yellow River. Meanwhile, the threshold of water and sediment regulation in Ningmeng Yellow River and the flow threshold of the main stream with sandy tributaries flowing into the inlet are given and determined through analysis. That is, the critical regulation discharge of Ningmeng Yellow River should be between 2 000 and 2 500 m³/s, the critical sediment concentration should be between 5.4 and 10.5 kg/m³, and the regulation time should be between 15 and 20 days. It is proved that the function of flood and sediment transport in Ningmeng Yellow River can be repaired and maintained by coordinating the relationship between water and sediment regimes. The flow threshold of the Yellow River preventing heavy sedimentation in junction of main stream and sandy tributary is 2 500 m³/s, with the dredger measures, the effective erosion threshold flow of sand dam is 3 000 m³/s. According to decreasing trend of the threshold of sediment inflow coefficient along the channel given by model tests, under the current riverbed boundary conditions of the Ningmeng reach, the required flow discharge is at least 2 600 m³/s. It shows that the Heishanxia Reservoir must reserve sufficient water and sediment control capacity. In term of macroeconomic regulation, accounting for the characteristics of diverse underlying surface conditions, numerous sediment sources, and significant influence of reservoir operation in river sediment transport, the main reservoir group is used as regulator and runoff and sediment are used as regulating objects in this research. Through the method of modular development, the wind-water-gravity erosion model, sediment transport model, ice forecast model all were integrated on the reservoir alignment model, and a digital basin model platform for the Ningmeng Yellow River is built, which can accurately simulate and forecast the water and sediment processes in large range and has been successfully debugged and applied in Xiaheyan-Shizuishan reach. In addition, in view of the river situation of Ningmeng Yellow River, such as the complicated river type, the ice knot dam during flood season, and the "sand dam" formed by the sudden flood of sandy tributaries in summer, the treatment m