| 珠江河网横向汊道水面线演变过程及原因探讨——以东平水道为例 |
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| 引用本文： | 王博芝,杨昊,欧素英,傅林曦,蔡华阳,杨清书.珠江河网横向汊道水面线演变过程及原因探讨——以东平水道为例[J].热带地理,2021,41(2):410-422. |
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| 作者姓名： | 王博芝 杨昊 欧素英 傅林曦 蔡华阳 杨清书 |
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| 作者单位： | 1.a. 河口水利技术国家地方联合工程实验室，广州 510275；b. 广东省海岸与岛礁工程技术研究中心，广州 510275；c. 南方海洋科学与 工程广东省实验室（珠海），珠海 519000;2.中山大学 海洋工程与技术学院 河口海岸研究所，广州 510275 |
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| 基金项目： | 国家重点研发计划项目(2016YFC0402600);国家自然科学基金项目(51979296)。 |
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| 摘 要： | 基于1960－2016年东平水道三水、紫洞、澜石、浮标厂月均潮差、余水位数据及三水、马口站月均流量数据，以1993年三水－马口分流比突变为切入口，探讨余水位坡度及潮波衰减率等径－潮动力改变下，东平水道水面线与余水位曲率的时空演变特征及其影响因素。结果表明：东平水道在1993年三水分流比剧增之后，1）余水位坡度或潮波衰减率与流量的双累积曲线斜率下降，即余水位坡度或潮波衰减率对流量的依赖性减弱；2）东平水道水面坡度整体下降且上游（紫洞－三水河段）降幅最大，不同季节坡度的变化率介于-67%~-4%，水面线由下凹转为上凸，即曲率由正转负。同时，曲率波动幅度明显减弱，1993年前曲率波动介于2×10-10~5.48×10-10，而1993年后波动介于-0.9×10-10~-0.07×10-10。上述曲率变化在冬季较夏季显著；3）上述水面线异变的主要原因为，东平水道中上游河道挖沙导致河床地形大幅下切、水位下降、来水量增大，且同时期的航道疏浚加剧这一变化；下游主要受滩涂围垦影响，河道淤浅。以上地形变化导致河道中游径、潮流量增大，径－潮双向顶托使水面线转变为上凸型。受北江上游飞来峡水库调蓄影响以及过水断面宽深比、海平面变化等季节性调节作用，东平水道冬季水面线及曲率变化较夏季显著。
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| 关 键 词： | 余水位坡度 潮波衰减率 余水位曲率 水面线 强人类活动 |
| 收稿时间： | 2020-05-26 |
Water Surface Profile Dynamics and Underlying Mechanism of Transverse Channel in Pearl River Channel Networks: A Case Study of the Dongping Channel |
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| Wang Bozhi,Yang Hao,Ou Suying,Fu Linxi,Cai Huayang,Yang Qingshu.Water Surface Profile Dynamics and Underlying Mechanism of Transverse Channel in Pearl River Channel Networks: A Case Study of the Dongping Channel[J].Tropical Geography,2021,41(2):410-422. |
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| Authors: | Wang Bozhi Yang Hao Ou Suying Fu Linxi Cai Huayang Yang Qingshu |
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| Institution: | 1.a. State and Local Joint Engineering Laboratory of Estuarine Hydraulic Technology, Guangzhou 510275, China; b. Guangdong Provincial Engineering Research Center of Coasts, Islands and Reefs, Guangzhou 510275, China; c. Southern Laboratory of Ocean Science and Engineering (Zhuhai), Zhuhai, 519000, China;2.Institute of Estuarine and Coastal Research, School of Marine Engineering and Technology, Sun Yat-sen University, Guangzhou 510275, China |
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| Abstract: | Since the 1980s,the Pearl River Delta has undergone rapid development on economic and social fronts.Owing to the impacts of large-scale and intensive human activities,the river discharge and sediment loads entering the Pearl River channel networks along with its morphology have changed drastically,leading to substantial alterations in spatial-temporal tide-river dynamics.Accordingly,the estuarine water surface profile has also experienced stepwise evolution.However,little attention has been paid to the mechanisms underlying waterlevel profile dynamics.In this study,the characteristics of and factors influencing the spatiotemporal evolution of the water surface profiles and residual water level curvature in the Dongping Channel were systematically explored based on the abrupt change in the Sanshui and Makou hydrological stations’flow diversion ratio in 1993,with the Dongping Channel considered as a case study.The obtained results are useful for setting scientific guidelines for evaluating morphological changes,adjusting flood control strategies,preventing saltwater intrusion,and constructing large-scale water conservancy projects.First,according to the abrupt change in the Sanshui and Makou hydrological stations’diversion ratio at the apex of the Pearl River channel networks,the evolution of the surface water profile dynamics in the Dongping Channel was divided into two phases:the prehuman period(1960-1992)and the post-human period(1993-2016).Subsequently,the dependence of the residual water level slope or tidal damping rate on discharge before and after the abrupt change in diversion ratio was studied using the double accumulation curve method.The residual water level curvature before and after human intervention was used to understand the dynamics of the residual water level slope and the resulting water surface profiles;in particular,the larger the curvature,the faster was the change in the residual water level.Meanwhile,the change in curvature from positive to negative(or vice versa)indicated a change in the shape from concave to convex(or vice versa).The results showed that:1)The slope of the double cumulative curve of the residual water level slope or the tidal damping rate with regard to the river discharge decreased,indicating that the dependence of the residual water level or the tidal damping rate on the river discharge decreased;2)the water surface slope of the Dongping Channel decreased as a whole,and the water surface slope upper reaches(Zidong-Sanshui reach)decreased the most.The rate of change of the gradient among the four seasons decreased by 4%to 67%.Meanwhile,the curvature fluctuation amplitude decreased,ranging from 2×10-10 to 5.48×10-10 before 1993,and from-0.9×10-10 to-0.07×10-10 after 1993;and 3)the main reason for the substantial change in the water surface profile was that sand excavation occurred in the middle and upper reaches of the Dongping Channel,leading to a substantial deepening of the river bed,a decrease in the water level,and an increase in water discharge.The lower reaches were mainly affected by tidal flat reclamation,resulting in channel deposition.Owing to the geometric changes,both the river discharge and tidal discharge increased in the middle reaches,leading to conversion of the water surface profile into an upward convex shape.Meanwhile,owing to the regulations for the Feilaixia Reservoir in the upper reaches of the Beijiang River and the seasonal regulation for cross-sectional width-depth ratio and sea-level change,the variation in the water surface curvature of the Dongping Channel in winter was much more significant than that in summer. |
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| Keywords: | residual water level slope tidal damping rate residual water level curvature water surface profile intensive human activities |
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