1.Nanjing Center,China Geological Survey;2.Wuhan Center,China Geological Survey;3.Chengdu University of Technology;4.Geological Survey of Jiangsu Province,;5.Geological Survey of Jiangsu Province;6.The Institute of Exploration Technology,Chinese Academy of Geological Sciences;7.Chengdu Center,China Geological Survey;8.China University of Geosciences Wuhan;9.East China Normal University
【研究目的】长江的形成和演化以及长江中下游地区周而复始的洪涝灾害，是亟待学术界破解的关键科学问题。【研究方法】通过采用冲积扇成因理论、联合沉积相剖面对比法、岩相古地理分析、高精度定年技术和遥感等方法，从流域视角剖析了长江中下游沿江砾石层成因、岩相古地理特征、长江上游三峡夷平面和阶地特征以及云南石鼓长江大拐湾成因。【研究结果】提出了早中更新世之交（距今75万年）长江东西贯通时限和长江中游地区全新世“一江（长江）四湖（云梦泽、彭蠡泽、洞庭湖和鄱阳湖）”江湖演化格局的认识，分析了在自然和人为作用下近代长江中下游地区洪涝灾害现状和影响因素，并结合长江演化规律及其对洪涝灾害防治启示，提出了 “再造云梦泽、扩张洞庭湖和鄱阳湖” 、“采砂扩湖、清淤改田”长江中下游洪涝灾害防治对策和下一步相关地质工作建议。【结论】早中更新世地质环境的重大调整是造成长江东西全线贯通的重要原因，长江中游地区洪涝灾害防治应充分考虑江湖演化规律，该研究成果可为长江经济带/长江流域国土空间规划、地质灾害防治和生态环境保护与修复提供基础支撑和理论依据。
This paper is the result of geological environment survey engineering. [Objective] The formation and evolution of the Yangtze River and the recurrent flood disasters in the middle and lower reaches of the Yangtze River are the key scientific problems to be solved urgently. [Methods] By using alluvial fan genetic theory, Combined sedimentary facies profile correlation method, lithofacies paleogeographic analysis, high-precision dating technology, remote sensing method and so on, From the perspective of the basin, the genesis of gravel layers and lithofacies paleogeographic characteristics along the middle and lower reaches of the Yangtze River, planation surface and terrace characteristics of the Three Gorges and the genesis of the great turn of Yangtze River in Shigu, Yunnan in the upper reaches of the Yangtze River are analyzed. [Results] The understandings of the east-west transconnection time of the Yangtze River at the turn of early-Middle Pleistocene (750,000 years ago) and the Holocene river lake evolution pattern of "one River (Yangtze River) and four lakes (Yunmengze, Peng Lize, Dongting lake and Poyang Lake)" in the middle reaches of the Yangtze River the are put forward. The present situation and influencing factors of flood disaster in the middle and lower reaches of the Yangtze River in modern times under the natural and man-made effects were analyzed, and the evolution law of the Yangtze River and its enlightenment to flood disaster prevention and control were combined. The prevention and control measures of flood disaster in the middle and lower reaches of the Yangtze River including "rebuilding Yunmengze, expanding Dongting Lake and Poyang Lake", " Sand exploiting expansion lake, removing silt and turned into farmland " and relevant geological suggestions for the next step were put forward. [Conclusions] The major adjustment of geological environment in the early and middle Pleistocene was an important reason for the connection of the east and west lines of the Yangtze River. The flood disaster prevention and control in the middle reaches of the Yangtze River should fully consider the evolution law of rivers and lakes. The research results can provide basic support and theoretical basis for the territorial space planning, geological disaster prevention and ecological environment protection and restoration of the Yangtze River Economic Belt/Yangtze River Basin.