【作者】 郑珊；

【导师】 吴保生；

【作者基本信息】 清华大学 ， 水利工程， 2013， 博士

【摘要】 论文选取我国黄河和美国图特河北汊作为典型案例，以河床演变普遍存在的滞后现象为主线，以描述河床演变过程的滞后响应模型为基础，探讨了不同扰动因素影响下河道的滞后响应特点和调整规律，建立了不同扰动因素协同作用下非平衡态河道复杂演变过程的计算方法，对选取典型案例的长时间河床非平衡态冲淤演变过程进行了模拟。论文成果对于深化对非平衡态河床演变规律的认识，发展非平衡态河床演变学理论和方法具有重要的学术意义和实用价值。基于河流系统的概念，在分析上游来水来沙条件和下游侵蚀基准面变化对冲积河流系统的不同作用机制基础上，建立了两种扰动因素协同作用下河床冲淤调整的平衡模式和平衡冲淤体的计算方法。对于受水沙条件和潼关高程共同影响的黄河小北干流和渭河下游的河床演变过程，采用三角形淤积体的平衡态计算模式，利用滞后响应模型计算了1960～2011年潼关高程抬升及水沙变化对黄河小北干流和渭河下游河道冲淤过程的影响，结果表明模型充分考虑了潼关高程和水沙条件对河道冲淤演变过程的协同作用，结果还显示潼关高程对河道冲淤的影响占主导地位，而近期河道的冲淤受水沙条件的影响较大。对于受水沙条件和河口淤积延伸影响的黄河下游河道的长系列冲淤演变过程，采用梯形淤积体的平衡态计算模式，结合滞后响应模型，建立了黄河下游历年累计淤积量的计算方法，模拟了1952～2010年黄河下游不同河段长时间的河道冲淤过程，计算效果较好，表明模型能够考虑水沙条件引起的沿程冲淤和河口延伸引起的溯源淤积；并且研究表明花园口~利津河段的河床淤积过程与水沙条件的变化密切相关，而孙口以下河段则受河口延伸的影响更为明显。对于受火山爆发影响的美国图特河北汊的河床演变，分析了河道垂向、横向及纵向的调整过程，研究表明河道的调整速率随时间非线性衰减，河床的调整在空间上呈现上冲下淤的一般趋势；根据平衡比降建立了河床平衡态的计算方法，进而采用滞后响应模型建立了图特河北汊河床深泓高程的计算方法，该方法不仅考虑了当前水沙条件对河床演变的影响，而且考虑了前期水沙条件的作用，用于模拟1980～2011年图特河北汊河床冲淤交替的变化过程，取得了令人满意的结果。更多还原

【Abstract】 This paper studied the characteristics of the delayed response of the fluvial systemsaffected by different disturbance. A method for simulating non-equilibrium fluvialprocesses was developed based on the delayed response model and the analysis of theequilibrium state of fluvial systems. The long term evolution processes of the YellowRiver reaches and the North Fork Toutle River in the United States were simulatedusing the proposed method. This paper enhances our understanding of non-equilibriumfluvial processes and contributes to the development of the theory and methods withrespect to channel evolution.Based on the concept of river system, the disturbance of alluvial rivers is dividedinto the runoff and sediment conditions and the base-level change at the downstream.The potential equilibrium state of the fluvial system affected by both the two factorswas studied and a method was developed for calculating the equilibrium value of theaggradation and degradation volume of channel reaches.Xiaobeiganliu and the lower Weihe River are both affected by water discharge andsediment load and the variation of Tongguan elevation. It’s assumed that channelreaches in their potential equilibrium state, compared to the initial boundaries, have adeposition body in the shape of a triangle. Based on the delayed response model and anequation developed for calculating the volume of triangular deposition body, a methodfor simulating the erosion and deposition processes of the river reaches was proposed.The adjustment processes of the river reaches during1960and2011were simulatedusing the proposed method. The results showed that the method takes into account theeffects of both Tongguan elevation and water and sediment conditions. Moreover, it’sshown that Tongguan elevation significantly affected the evolution of the channelreaches, while income water and sediment conditions had greater influence on therecent aggradation and degradation processes of rivers.The lower Yellow Rive(rLYR)is affected by the water and sediment conditions aswell as the extension of the river mouth. Assuming the potential equilibrium channelreach has a trapezoidal deposition body, a calculation method for the volume of thetrapezoidal deposition body combined with the delayed response model were used to develop the calculation method for the non-equilibrium fluvial processes of the LYR.The evolution processs of the LYR during1952and2010were simulated using theproposed method and satisfactory results were obtained. The results showed that theproposed method considers the effects of water and sediment variation and estuaryextension on channel evolution. Meanwhile, it’s indicated that the aggradation anddegradation processes of the channel reach between Huayuankou and Lijin were closelyrelated to the income water and sediment conditions while the reach downstreamSunkou gaging station was more significantly affected by the rise of base-level causedby estuary extension.The vertical, lateral and longitudinal variations of channel geometry of the NorthFork Toutle River （NFTR） following volcanic eruption were analyzed. The resultsshowed that NFTR adjusted most rapidly during the first3years after the eruption. Therate of adjustment decayed as time elapsed and the channel gradually tended to a stableor equilibrium state. Moreover, the channel bed of the upper NFTR was severelydegraded while that of the lower reach aggraded. The aggradation and degradationprocesses of the channel bed during1980and2011were simulated by the delayedresponse model. The results showed that different modes of the delayed response modelcan well simulate the relaxation paths of the channel bed of the NFTR. Since thedelayed response model considers the cumulative effects of the water and sedimentconditions on the evolution of the river, it is able to simulate the adjustment processesof the river from a perturbed state after the eruption to a certain steady-state.更多还原