Geomorphic dynamics of alluvial rivers in response to upstream damming have substantial impacts on navigation,habitat protection,and channel stability.The purpose of this study was to determine how flow and sediment regimes,and meander characteristics affect the morphological adjustment of bends in the Lower Jingjiang Reach(LJR)before and after the Three Gorges Project(TGP).Based on detailed field measurements and hydrologi-cal and topographic datasets from 1991 to 2016,banks and point bars morphodynamics of 12 continuous bends in the LJR were comprehensively analyzed.Point bars in the LJR mainly experienced a net deposition before the TGP operation,but substantially deteriorated with a net erosion rate of 4.6 million m3 yr-1 in the post-TGP periods(2003-2016),and erosion on heads and upstream margins of point bars was a general adjustment pattern in the 12 bends.The most significant morphological changes of point bars and banks occurred in 2006-2011,indicating a delayed response of the channel evolution of the LJR to damming.Detailed ob-servations suggested that the medium discharges(16,000-18,000 m3 s-1)were the most contributive discharges in shaping the morphology of point bars and banks in the LJR after damming.In addition,we revealed the importance of sediment supply on meander defor-mation of the LJR,driven by sediment exchange over point bars,and more upstream plan-form deformation tended to occur in bends with high sinuosity(＞2.0)in the LJR after damming.The relationship between meander deformation and sinuosity was manifested through the geometric adjustment range of point bars.The morphological adjustments of point bars in the highly curved or compound bends of the LJR were more conducive to cause flow deflections,leading to form concave-bank bars after the TGP operation.

WANG Hongyang;LU Yongjun;YAO Shiming;ZUO Liqin;LIU Huaixiang

State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China;State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Nanjing Hydraulic Re-search Institute,Nanjing 210029,China;Key Laboratory of River Regulation and Flood Control of Ministry of Water Resources,Changjiang River Scientific Research Institute,Wuhan 430010,China

地理学报（英文版）

[1]WANG Hongyang;LU Yongjun;YAO Shiming;ZUO Liqin;LIU Huaixiang-.Bank and point bar morphodynamics in the Lower Jingjiang Reach of the Yangtze River in response to the Three Gorges Project)[J].地理学报（英文版）,2022(08):1530-1556

Jingjiang,Geomorphic,LJR,hydrologi,sinuosity

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