北江下游河道地形演变及其对物质输运的影响分析  

Analysis of the Topographic Evolution of the Lower Beijiang River and its Impact on Material Transport

作　　者：朱政涛 丁灿 黄东[1,3] 刘画眉 陈鑫池[1,3] ZHU Zheng-tao;DING Can;HUANG Dong;LIU Hua-mei;CHEN Xin-chi(Guangdong Research Institute of Water Resources and Hydropower,Guangzhou 510000,Guangdong Province,China;School of Civil Engineering,Sun Yat-sen University,Zhuhai 519000,Guangdong Province,China;National and Local Joint Engineering Laboratory of Estuarine Water Technology,Guangzhou 510000,Guangdong Province,China)

机构地区：[1]广东省水利水电科学研究院,广东广州510000 [2]中山大学土木工程学院,广东珠海519000 [3]河口水利技术国家地方联合工程实验室,广东广州510000

出　　处：《中国农村水利水电》2024年第7期85-94,共10页China Rural Water and Hydropower

基　　金：广东省水利科技创新项目(2023-06);2023年省科技创新战略专项资金科研项目(sky2023-05)。

摘　　要：基于1998、2012和2020年三期河道实测地形数据,较为系统地研究了北江下游石角-三水河段近20年来河道地形的时空变化特征,同时采用有限体积法建立研究区域二维水动力水质耦合模型,定量研究了不同地形和洪水量级下石角-三水河段水力滞留时间的空间分布。研究结果表明,1998-2012年该段河道存在明显冲刷,研究区域平均高程降低2.9 m,平均深泓点高程降低7.8 m,河道断面存在显著的由宽浅向窄深发展的趋势;2012-2020年,研究区域平均高程降低0.7 m,平均深泓点高程增加0.4 m,变幅显著低于1998-2012年,河道断面形态趋于稳定。研究区域水力滞留时间的空间分布表现为从上游至下游逐渐增大,且河道中心的水力滞留时间一般低于两岸。在同一地形条件下,洪水量级越大,研究区域水力滞留时间越小,物质输运速度越快;在2020年地形条件下,P=1%时出口位置水力滞留时间为11.99 h,低于P=5%时的12.69 h及P=20%时的13.08 h;从时间尺度来看,1998-2020年研究区域平均水力滞留时间增加0.72~0.75 h,出口位置水力滞留时间增加2.20~2.35 h。通过对比出口位置水力滞留时间与区间内各水文站点平均流速,发现二者呈显著的负相关性,并最终采用幂函数建立水力滞留时间的估算公式。相关研究成果可为今后北江下游突发污染事故的预警和管理提供科学参考。Based on the measured topographic data in the lower reaches of the Beijiang River(Shijiao-Sanshui)in 1998,2012 and 2020,a systematic study was conducted on the spatiotemporal changes of the river terrain over the past 20 years.A two-dimensional hydrodynamic and water quality coupling numerical model was then established for the study area using the finite volume method, aiming to quantitativelyinvestigate the spatial distribution of the hydraulic retention time under different terrains and flood magnitudes. The results indicated thatthere existed significant erosion in the river channel from 1998 to 2012, with an average elevation decrease of 2.9 m in the entire study areaand 7.8 m in the thalweg, showing a notable trend from wide and shallow to narrow and deep in the river section. From 2012 to 2020, the av⁃erage elevation of the study area decreased by 0.7 m, while the average elevation of the thalweg increased by 0.4 m. Both changes were signif⁃icantly lower than those between 1998 and 2012. Correspondingly, the morphology of the river section tended to stabilize. The spatial distri⁃bution of the hydraulic retention time in the study area showed a gradual increase from upstream to downstream, and the time in the center ofthe river was generally lower than that on both banks. Under the same terrain conditions, larger flood magnitudes usually corresponded to theshorter hydraulic retention time in the study area, suggesting a faster transport speed of the substance. Under the terrain conditions in 2020,the hydraulic retention time at the outlet position under P = 1% design flood was 11.99 hours, which was lower than 12.69 hours under P =5% design flood and 13.08 hours under P = 20% design flood. From the time scale perspective, the average hydraulic retention time in thestudy area increased by 0.72~0.75 hours between 1998 and 2020, and the hydraulic retention time at the outlet location increased by 2.20~2.35 hours. By comparing the hydraulic retention time at the outlet location with the average flow veloc

关 键 词：北江下游 地形演变 水动力水质模型 水力滞留时间 

分 类 号：TV143[水利工程—水力学及河流动力学]