陈小齐, 余明辉, 刘长杰, 田浩永, 刘画眉. 珠江三角洲近年地形不均匀变化对洪季水动力特征的影响[J]. 水科学进展, 2020, 31(1): 81-90. DOI: 10.14042/j.cnki.32.1309.2020.01.009
引用本文: 陈小齐, 余明辉, 刘长杰, 田浩永, 刘画眉. 珠江三角洲近年地形不均匀变化对洪季水动力特征的影响[J]. 水科学进展, 2020, 31(1): 81-90. DOI: 10.14042/j.cnki.32.1309.2020.01.009
CHEN Xiaoqi, YU Minghui, LIU Changjie, TIAN Haoyong, LIU Huamei. Impact of recent uneven channel evolution on hydrodynamic characteristics during flood season in the Pearl River Delta[J]. Advances in Water Science, 2020, 31(1): 81-90. DOI: 10.14042/j.cnki.32.1309.2020.01.009
Citation: CHEN Xiaoqi, YU Minghui, LIU Changjie, TIAN Haoyong, LIU Huamei. Impact of recent uneven channel evolution on hydrodynamic characteristics during flood season in the Pearl River Delta[J]. Advances in Water Science, 2020, 31(1): 81-90. DOI: 10.14042/j.cnki.32.1309.2020.01.009

珠江三角洲近年地形不均匀变化对洪季水动力特征的影响

Impact of recent uneven channel evolution on hydrodynamic characteristics during flood season in the Pearl River Delta

  • 摘要: 为探明在新水沙条件和人类活动的影响下珠江三角洲河网地形变化与洪季水动力特征变化之间的关系,以1999—2008年为研究时段,基于1999年地形建立一维河网数学模型,复演珠江三角洲地区"08·6"洪水,并与"08·6"实测资料进行对比,分析河网地形变化对洪季水动力特征的影响。结果表明:①珠江三角洲河网地形整体下切加强了河道行洪能力,在遭遇洪峰30年一遇的"08·6"洪水时洪水位整体下降,三角洲顶部马口站洪水位最大降幅达到0.9 m;②河网内潮差和潮汐传播速度增大,潮区界上移至马口、三水以上;③西江河网地形下切幅度大于北江河网,地形不均匀下切导致河网节点分流比改变,西江河网洪水期分流增加2%,马口站和天河站洪峰流量增幅分别接近1 500 m3/s和1 000 m3/s;④西江马口站分流比随上游洪水流量增大而减小的趋势没有改变,但地形不均匀下切导致其变化梯度增大。珠江三角洲近年地形的不均匀下切,是近年珠江三角洲河网地区,特别是河网腹地洪水灾害有所减轻的主要原因之一。

     

    Abstract: To explore the relationship between changes of riverbed topography and adjustments of flood dynamic characteristics of the Pearl River Delta (PRD) in 1999-2008, a one-dimensional river network mathematical model was established based on the surveyed topography in 1999. The "08·6" flood was first reproduced and model-data comparison was implemented; then, the impact of topography change of river network on hydrodynamic characteristics during flood season in the PRD was investigated. Results show that the flood diversion capacity of channels is increased due to the down-cutting of riverbed in the PRD. During the flood "08·6" (a recurrence period of 30 years), the water surface elevations are generally lower than before, with a maximum decrease about 0.9 m at the Makou station. The tidal range and tidal velocity are found to increase, making the tidal limit move to above Makou and Sanshui stations. The riverbed down-cutting in the Xijiang river networks is larger than that in the Beijiang river networks. Uneven riverbed down-cutting leads to changes of discharge ratio in river network nodes, during the flood season, flood diversion of the Xijiang river networks increases by 2%, and the peak discharge of the Makou and Tianhe stations increass by about 1 500 m3/s and 1 000 m3/s, respectively. The trend that the diversion ratio at Makou station decreases with the increase of upstream flood discharge does not change. Nevertheless, the uneven-riverbed-down-cutting caused diversion ratio changes increase. The riverbed uneven down-cutting in recent years is the major reason for the reduction of flood risk of the river networks in the PRD, especially in the central region of the PRD.

     

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