【作者】 范念念； 褚忠信； 姜鲁光； 朱猛； Marwan Hassan； 吴保生； 刘兴年；

【Author】 FAN Niannian;CHU Zhongxin;JIANG Luguang;ZHU Meng;Marwan HASSAN;WU Baosheng;LIU Xingnian;State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resource & Hydropower,Sichuan University;College of Marine Geosciences,Ocean University of China;Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences;Department of Geography,University of British Columbia;State Key Laboratory of Hydroscience and Hydraulic Engineering,Tsinghua University;

【机构】 四川大学水力学与山区河流开发保护国家重点实验室； 中国海洋大学海洋地球科学学院； 中国科学院地理科学与资源研究所； Department of Geography,University of British Columbia； 清华大学水沙科学与水利水电工程国家重点实验室；

【摘要】 河流袭夺事件在山区河流侵蚀及地貌演化过程中起重要作用,然而,该事件的发生需要很长的时间尺度,因此相对稀少,且即便是报道的河流袭夺案例,也常缺乏十分确凿的证据,其发生时间更是难以较准确确定。这些事实限制了山区河流侵蚀和地貌演化的研究。通过详尽的野外考察,先从大转弯,尼克点等地貌特征推断了山东沂蒙山区柴汶河对沂河的袭夺,进而通过古河床卵石定向排列所指示的古水流方向,确认了河流袭夺的确实发生。通过河流袭夺前形成的湖相沉积物,测年得到发生年代为距今9500年前。因该次河流袭夺年代较近,袭夺弯和尼克点仍然保留,为河流袭夺以及基岩河床下切侵蚀的研究提供了很好的天然实例。该次河流袭夺使坚硬的花岗岩在一万年内最大下切27m,尼克点溯源移动1.4km,对应的年均下切和移动速率分别达2.8mm/年和15cm/年。研究表明河流袭夺后的基岩侵蚀下切与尼克点的溯源移动密切相关,进而建立了数学模型,揭示了河流袭夺后基岩侵蚀的时间-空间变异性。更多还原

【Abstract】 River capture is a dramatic and abrupt natural process of internal competition through which mountainous landscapes evolve and respond to perturbations in tectonics,sea level,and climate.River captures occur when the growth of a river network outpaces its neighbors,resulting in a victor that "steals" the neighboring headwaters.While capture events occur regularly in numerical models of landscape evolution,field observations of capture events are rare,or too old to conserve the traces or confine the date.Here,we document a 9000 years river capture in the Yimeng Mountains,China,that we identified based on the reversal in paleo-flow direction indicating by imbricated cobbles.As this event is relatively recent,the associated landforms(e.g.,an elbow and two knickpoints) are preserved and the erosion can be well constrained.Specifically,the granite bedrock channel has incised 27 m,and the captured-river and reversed-river knickpoints have retreated 1.4 km and 0.78 km upstream,respectively.Our numerical model illustrate the spatial and temporal variations in scale that are linked to the retreat and shrinkage of knickpoint and the traces induced by river capture could be disappear within relative short time seale.更多还原