三角洲河道发育演变特征与影响机制研究  

Study on the Characteristics and Mechanisms of Deltaic Channel Evolution

作　　者：李薇[1] 朱乐红 胡鹏[1] LI Wei;ZHU Lehong;HU Peng(Ocean College,Zhejiang University,Zhoushan 316021,China)

机构地区：[1]浙江大学海洋学院,浙江舟山316021

出　　处：《应用基础与工程科学学报》2025年第1期158-168,共11页Journal of Basic Science and Engineering

基　　金：国家重点研发计划项目(2021YFE0206200);国家自然科学基金项目(12272349,12172331)。

摘　　要：为揭示三角洲上河流改道后新河道发育的主要影响因素,并阐明其地貌演化特征,采用充分考虑水-沙-床相互作用的平面二维全耦合数学模型,在概化扇形三角洲上开展“散乱-归股-单一”的河道地貌演变数值实验.结果表明,初始高低起伏的滩面地形是复演初期河道散乱发育的关键.发育过程中的河道地貌形态演变特征及时间尺度与三角洲坡度和水沙边界条件密切相关.在恒定来水来沙条件下,小底坡或小流量情况更易形成前期散乱游荡的河道,而大底坡或大流量则加速水流的归股贯通;来沙较少时,河道以冲刷为主,来沙较多时以淤滩、刷槽为主.下游边界潮位波动的增强将促进流路贯通,而泥沙在水下三角洲前缘的淤积使流路贯通时间显著延长.在非恒定来水来沙条件下,河道发育前期,汛期主槽刷深、支汊浅沟发育,而非汛期仅主槽过水;发育后期则始终呈现单一归顺的河道形态,且汛期对主槽的维持起主导作用.In order to reveal the main influencing factors and characteristics of deltaic channel evolution following avulsion,numerical experiments were conducted by a fully coupled hydro-sediment-morphodynamic model with the focus on the“wandering-braiding-merging”processes in schematic fan deltas.Results show that the initial undulating topography is critical for reproducing the wandering patterns in the early stage.The morphological evolution characteristics and time scales of channel development are highly related to the deltaic slope as well as the flow and sediment boundary conditions.A small bed slope and a low discharge favor the wandering processes,while a large bed slope and a high discharge favor merging and routing processes under steady flow condition.Channel erosion is dominant at low sediment concentration,whereas channel erosion and levee-lip accretion occur simultaneously at high sediment concentration.Enhanced tidal force at downstream boundary may accelerate the flow routing processes,whereas the seaward deposition on the subaqueous slope shows an opposite effect.Under unsteady flow conditions,the early stage is characterized by the development of main channel and branches at the flood season but only wetted main channel at the dry season;while the later stage is featured by a single main channel all the time,which is maintained by the flood discharge.

关 键 词：黄河三角洲 河道发育 地貌形态演变 时间尺度 影响机制 数值模拟 

分 类 号：TV148.3[水利工程—水力学及河流动力学]