Hydrodynamic Characteristics at the Confluence Zone of Jing River and Wei River

涇河與渭河交匯區水動力特性研究

10.6937/TWC.202212_70(4).0003

XIA SHEN；SHENG LI；HAOTIAN ZHANG；XIAOYAN LIU；HAN GUO；XUEGUI ZHANG

Natural river confluence ； Numerical simulation ； Flow structure ； Turbulent kinetic energy ； Discharge ratio ； 天然河流交匯區 ； 數值模擬 ； 水流結構 ； 紊動能 ； 匯流比

台灣水利

70卷4期（2022 / 12 / 01）

22 - 39

英文;繁體中文

River confluences are important nodes in the river network, and it is of great significance to clarify the flow characteristics of the river confluence for ecological environment protection. Previous studies on river confluences have mainly focused on confluence sinks and small natural river confluences. However, large natural river confluences with complex channel boundaries generally have extremely complex hydrodynamic characteristics that are difficult to clarify. In this study, the confluence zone of Jing River and Wei River (the most famous confluence in the Weihe Plain of northwest China) is selected as the research object, and the complex hydrodynamic characteristics of this asymmetrical large-scale confluence are investigated using two-dimensional numerical simulations. The results show that the confluence zone of the Jing River and Wei River is a typical curved mainstream type, which exhibits complex flow zoning characteristics due to its irregular channel profile and more central bars, and the confluence zone characteristics varied in different hydrological periods; with the increase of confluence ratio, the mainstream is strengthened by the supporting action of tributaries, the mainstream zone and the shear layer zone are close to the convex bank, and the velocity deviation zone increases; the turbulent kinetic energy in the confluence zone is distributed in a striped pattern, and the turbulent kinetic energy of the mainstream is about 10 times that of the tributaries; the turbulent kinetic energy in the confluence zone is larger in the mixing zone of the mainstream and tributaries, and in the compression zone squeezed by the central bars, while the turbulent kinetic energy in the circulation zone is lower. The results of this study can provide a scientific basis for the study of similar natural river confluences and are of great significance for the evolvement of the Weihe Basin in China and for water and ecological protection.

河流交匯區是組成河網水系的重要節點，明晰交匯區水流特徵對交匯區生態環境保護具有重大意義。以往對交匯區的研究對象主要為交匯水槽與小型天然河流交匯區。然而，具有複雜河道邊界的大型天然河流交匯區一般存在著極為複雜的水動力特徵難以明晰。本研究選取中國西北渭河平原最著名的涇河與渭河交匯區，通過二維數值模擬的方法研究了該非對稱大型交匯區複雜的水動力特性。結果表明：涇河與渭河交匯區屬於典型的彎曲幹流型交匯區，因其河岸輪廓不規則且江心洲較多的特點表現出複雜的水流分區特徵，且在不同水文時期的交匯區分區特徵存在明顯差異；隨著匯流比的增大，幹流受支流頂託作用加強，主流區和剪切層區向凸岸靠近，速度偏向區增大；交匯區紊動能較大區域呈條帶狀分佈，幹流的紊動能約為支流的10倍，交匯區干支流摻混區以及受江心洲擠壓的壓縮區紊動能較大，環流區的紊動能較小。本研究成果可為類似的天然河流交匯區研究提供科學依據，對中國渭河流域河道演變及水生態環境保護具有重要意義。

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