文章摘要
林芬芬,夏军强,周美蓉,邓珊珊.下荆江河槽形态及过流能力调整对上下游边界条件的响应[J].水利学报,2019,50(5):641-649
下荆江河槽形态及过流能力调整对上下游边界条件的响应
Recent response of bankfull channel geometry and flood-discharge capacity in the Lower Jingjiang Reach to upstream and downstream boundary conditions
投稿时间:2018-09-01  
DOI:10.13243/j.cnki.slxb.20180800
中文关键词: 平滩河槽形态  过流能力  警戒水位  水流冲刷强度  侵蚀基准面  下荆江河段
英文关键词: bankfull channel geometry  flood-discharge capacity  warning level  fluvial erosion intensity  lo-cal base-level  Lower Jingjiang Reach
基金项目:国家重点研发计划(2016YFC0402305);国家自然科学基金项目(51725902,51579186)
作者单位E-mail
林芬芬 武汉大学 水资源与水电工程科学国家重点实验室, 湖北 武汉 430072  
夏军强 武汉大学 水资源与水电工程科学国家重点实验室, 湖北 武汉 430072 xiajq@whu.edu.cn 
周美蓉 武汉大学 水资源与水电工程科学国家重点实验室, 湖北 武汉 430072  
邓珊珊 武汉大学 水资源与水电工程科学国家重点实验室, 湖北 武汉 430072  
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中文摘要:
      受三峡工程运用与洞庭湖出流顶托影响,下荆江河段的进口水沙条件及其出口侵蚀基准面发生改变,河床冲淤调整剧烈,平滩河槽形态及过流能力变化显著,威胁到两岸的防洪安全。首先采用一维水动力学模型及河段平均的河床演变分析方法,计算了下荆江2002-2016年河段尺度的平滩特征值(平滩宽度Wbf、水深Hbf、面积Abf及流量Qbf),以及石首与监利两站相应警戒水位下的过流流量(QwnSSQwnJL)。其次分析了上述参数对上下游边界条件的响应,并建立了这些参数与前5年汛期平均水流冲刷强度F5f(上边界)、当年上下游汛期平均水位差ΔZf(下边界)之间的单因素及多因素响应关系,并对综合关系式进行了率定与验证。结果表明:(1)受大规模护岸工程控制,下荆江河床调整以河段平滩水深增加为主,增幅为8.8%,相应宽深比减小8%,河床趋于窄深;(2)河道过流能力年际间变化较大,无明显单向增加或减少趋势,其中河段平滩流量介于27 401~34 548 m3/s之间,多年平均值为31 335 m3/s,而石首及监利两站警戒水位下过流流量的多年平均值分别为36 976、34 381 m3/s;(3)在综合关系式中,对于河段平滩面积Abf而言,上边界F5f占比的平均值约为96%,且AbfF5f的增加而增大;对于河道过流能力(QbfQwnSSQwnJL)而言,下边界ΔZf占比的平均值约为86%,且QbfQwnSSQwnJL均随ΔZf的增加而增大。故下荆江河段平滩河槽形态调整主要与进口水沙条件有关,而过流能力调整主要受出口侵蚀基准面条件(洞庭湖出流顶托)控制。
英文摘要:
      The Lower Jingjiang Reach (LJR) underwent remarkable morphodynamic evolution owing to the combined effects of the altered flow-sediment regimes caused by the upstream operation of the Three Gorg-es Project (TGP), and the local base-level changes because of the downstream confluence from the Dongting Lake. Variations in bankfull channel geometry and flood-discharge capacity of this reach were in-vestigated by a one-dimensional hydrodynamic model and a reach-averaged method, covering the changes in reach-scale bankfull geometry (width Wbf, depth Hbf and area Abf) and discharge (Qbf), as well as the specified discharge under the warning levels at the water gauge stations of Shishou (QwnSS) and Jianli (QwnJL) during the period 2002-2016. Furthermore, these variables were represented by empirical functions of two key hydrodynamic parameters, covering the previous five-year average fluvial erosion intensity during flood seasons at Jianli (upstream boundary F5f), and the corresponding difference between the average wa-ter stages at Xinchang and Lianhuatang (downstream boundary ΔZf). Calculated results indicate that:(i) owing to the impacts of various river regulation engineering,channel evolution in the LJR was mainly char-acterised by the variation in bankfull depth, with an increase of 8.8% and 9.9% in the reach-scale bank-full depth and area from 2002 to 2016, respectively;(ii) the flood-discharge capacity of this reach varied greatly in different years after the TGP operation, showing no monotone increasing or decreasing trend, with the average values of Qbf,QwnSS,QwnJL being 31 335,36 976 and 34 381 m3/s,respectively;and (iii) the adjustments in the channel geometry were mainly controlled by the upstream boundary condition, with the value of Abf increasing with a larger value of F5f, but the variation in the flood-discharge capacity was mainly influenced by the downstream boundary condition,with the values of Qbf,QwnSS and QwnJL increas-ing with a larger value of ΔZf.
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