长江口河段近期冲淤演变过程及未来趋势预测
Recent Morphological Evolution Processes and Prediction on Future Evolution Trend of the Changjiang Estuary
作者：栾华龙(长江科学院 河流研究所, 湖北 武汉 430010;港口航道泥沙工程交通行业重点实验室, 江苏 南京 210024)；刘同宦(长江科学院 河流研究所, 湖北 武汉 430010)；丁平兴(华东师范大学 河口海岸学国家重点实验室, 上海 200062)
Author：LUAN Hualong(River Dept., Changjiang River Scientific Research Inst., Wuhan 430010, China;Key Lab. of Port, Waterway and Sedimentation Eng. of Ministry of Transport, Nanjing 210024, China)；LIU Tonghuan(River Dept., Changjiang River Scientific Research Inst., Wuhan 430010, China)；DING Pingxing(State Key Lab. of Estuarine and Coastal Research, East China Normal Univ., Shanghai 200062, China)
收稿日期：2018-03-09 年卷（期）页码：2019,51(2):21-27
期刊名称：工程科学与技术
Journal Name：Advanced Engineering Sciences
关键字：冲淤演变;河流来沙减少;数值模拟;演变趋势预测;长江口
Key words：morphological evolution;fluvial sediment decline;numerical modeling;evolution trend prediction;Changjiang Estuary
基金项目：国家重点研发计划项目资助（2016YFC0402307）；中央级公益性科研院所基本科研业务费专项资金资助（CKSF2019167/HL）；港口航道泥沙工程交通行业重点实验室开放基金资助项目（Yn918005）；国家自然科学基金项目资助（51679010；51339001）
中文摘要
随着三峡及其上游梯级水库的相继运行使用，长江中下游输沙量锐减，坝下游河道发生长时段、长距离的冲刷，并快速向河口地区发展。研究长江口近期冲淤演变过程及主控因子，并对未来演变趋势进行合理可靠的预测，是当前河口演变及治理研究的一大难题。利用GIS方法定量分析了长江口河段（徐六泾至横沙）1997年以来的冲淤演变特征，在此基础上使用经充分率定和验证后的长江口年代际冲淤演变数学模型（Delft3D），预测至2030年和2050年长江口河段冲淤演变趋势。根据实测冲淤过程定量分析可知，1997-2015年长江口河段局部河势发生显著调整，整体呈冲刷下切态势，冲刷强度随来沙量减少而增大；其中，2010-2015年年均净冲刷量达0.75 亿m3，且冲刷主要分布于10 m以下的深槽，浅滩以淤积为主。数值模拟预测结果表明：现状来沙量（1.25 亿t/a）条件下该河段2015-2030年保持强烈冲刷；2030-2050年冲刷有所减弱，但在极端低来沙量（1.00 亿t/a）条件下维持强烈冲刷，且存在由“淤滩刷槽”转变为“刷滩刷槽”的趋势。在自然条件及人类活动的双重影响下，河口冲淤演变过程复杂多变，作者所给出的演变趋势预测结果可为长江口综合整治提供技术支撑。
英文摘要
With the operations of the Three Gorges Dam and its upstream cascade reservoirs, sediment load in the middle and lower reaches of the Changjiang River has decreased sharply, and the long-term and long-distance riverbed erosion has been extending towards the Estuary. Understanding the controlling factors of morphological processes and future evolution trend of the Changjiang Estuary is a major question for estuarine evolution and regulation. Using GIS techniques, morphological evolution of the Changjiang Estuary (Xuliujing to Hengsha) since 1997 were quantitatively analyzed, and the evolution trends till 2030 and 2050 were predicted by a well calibrated and validated numerical model (Delft3D). The results indicated that the study area shows overall erosion with significant local changes in 1997-2015. The erosion gradually increases as the sediment discharge decreases sharply, and the net erosion volume in 2010-2015 is as high as 75 million m3. Erosion mainly occurs at deep channel lower than 10 m, while the shallow shoals are dominated by accretion. Model predictions indicated that the study area would maintain strong erosion in 2015-2030 under present sediment supply condition (125 million t/a) and the erosion may decrease in 2030-2050 due to the increased resistance of river bed erosion. However, strong erosion still occurs under extremely low sediment supply (100 million t/a) with conversion from accretion to erosion at shallow shoals. Under the combined natural and human impacts, estuarine evolution processes are complex, and the evolution trend could be an important guidance to the integrated regulation of the Changjiang Estuary.
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