【作者】 余新明；

【导师】 谈广鸣；

【作者基本信息】 武汉大学 ， 水力学及河流动力学， 2004， 硕士

【摘要】 河道分流是冲积河道中一种常见的形式，江心洲、江心滩可以引起河道分流，而分水道、引水渠也是一种常见的河道分流形式。目前，在对河道分流的认识与治理开发上虽取得了不少成绩，但随着社会经济的发展，人们对分流河道演变规律的认识与治理要求越来越高，随着人类对河流改造活动的加剧，河道的水沙条件可能发生急剧的改变，这些变化有可能使分流分沙的缓慢变化加剧，甚至改变原来的分流规律，许多研究者对分流分沙进行了较深入的研究，并能较好地解决了工程实际问题。然而，这些研究基本上都忽略了分流口附近水流结构因支流的引水而发生改变，特别是在河道发生了一定的冲淤变化后，这些变化更加变得复杂。当干流河道发生冲淤后将引起河流系统中的水、沙、河床之间相互关系的改变，这将会进一步导致其分流分沙规律的改变，因此对河道发生冲淤变化后的分水分沙问题的研究将对工程与生产实践具有重大的指导意义，同时也具有较大的理论意义。 根据这个主题全文主要讨论了以下三个方面。 第一部分是河道冲淤对水位变化情况的分析。该部分主要是分析和总结不同特点河道中冲淤变化与水位升降之间的关系。通过一定概化处理，分类计算河道冲淤对水位变化的影响，初步分析了不同断面形态及不同冲淤幅度情况下河道水位的变化规律，此外还通过分析水库下游的分流河道演变特性，为进一步分析分流河道发生冲淤变化后分流分沙的变化情况。 第二部分主要是从干流的冲淤变化来对河道的分流分沙进行初步的研究。由于干流的冲淤改变了分流道河底相对高程，从而改变了分流道的分流分沙，而在这方面的有关研究很少，特别是在三峡水利工程建成后，因其下游河道将经历先冲后淤的一段很长的过程，这将改变三口的分流分沙的发展，故而影响到江湖关系以及防洪策略。该部分主要是根据水力学及河流动力学的基本原理，考虑了坎高相对变化和河床冲淤与水位下降的关系，建立了河道发生冲淤变化后的分流分沙计算公式，通过概化水槽对公式进行了合理性分析及用荆江裁弯后的实测数据对公式进行了初步的验证，以外还对不同断面形态河段的分流分沙计算公式进行了初步的探讨。 第三部分是工程应用。该部分对取水口位于荆江河段的引江济汉工程分流道淤积进行计算，计算考虑了三峡水库运行后的荆江河道的冲淤，并应用了本文提出的分流分沙模式，根据计算结果修改了公式的参数，使模型在运用上能够满足工程要求。更多还原

【Abstract】 River diversion is a familiar form of alluvial river, which is often caused by ait and chur. At the same time, emissary and headwater channel also is a familiar form of river diversion. The evolvement of Diffluence River is the more complicated than Single River, because the diversion’s thing is changed with channel’s distortion. The river diversion is the general reflection of a good many factors, which mutually influence and adjust. In particular, when main channel occurs scouring-silting change, which causes the movement of water, sediment, and river bed in river system, the diversion will more be changed, with the study on division of discharge and sediment been further into, some practical engineering problem are solved. However, such researches basically neglect a fact that flow structure near diversion gap charge because of distributary’s drawing water. Especially study on the influence of the erosion and deposition of Riverbed to diversion of discharge and sediment important guide role to the planning of drainage area developing and programming, and theoretical value is significant. The paper consists of three parts to focus the above problems.The first part is about water level variation according to different riverbed deformation in river channels of several kinds of cross section shape analysis. In this paper, water level variation according to different riverbed deformation in river channels with different kinds of cross section shape is analyzed. With calculation of simplified channel models, the relation between water level change and channel erosion is presented.The second part is about influence to diversion ratio because of the water level variation in mainstream. The erosion and deposition state of mainstream may change the elevation of the river bottom, so as to change the diversion of flow and sediment. But little work is done about this field. Based on the result of formers’, this paper works on the influence of the main stream (whether erosion or deposition) to the diversion of flow and sediment mainly. Further study of the evolution law and the factors of river’s diversion will be useful to revolve the relationship between Yangtze River and Dongting Lake. The quantificational equation is developed to describe the relation between mainstream riverbed erosion& deposition and the variation of diversion ratio of flow and sediment the equation is verified with the field data of diversion change of the three diversion in Jingjiang Riverafter the river cutoff.The third part is about practical application. The most important influence is the distributary channel’s deposition to irrigation channel. So in this chapter, through distributary channel’s deposition computing the irrigation channel lied to the work of water transfer from the Yangtze River to Hanjiang in Jingjiang Reach, the model is modified to satisfy the work’s demand in precision and appliance.更多还原