Initiation and recession of the fluvial knickpoints:A case study from the Yalu River-Wangtian'e volcanic region,northeastern China  

作　　者：ZHANG HuiPing ZHANG PeiZhen FAN QiCheng 

机构地区：[1]State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China

出　　处：《Science China Earth Sciences》2011年第11期1746-1753,共8页中国科学（地球科学英文版）

基　　金：supported jointly by National Science Foundation of China (Grant Nos. 40702028, 41030317);State Key Laboratory of Earthquake Dynamics (Grant Nos. LED2009A06,LED2008A02);Zhang Huiping was also supported as a visiting professor to CU by China Scholarship Council (Grant No. 2007106279)

摘　　要：Initiation and recession of the knickpoints are significant boundary condition for processes of fluvial system. The distribution and recession rates of knickpoints contain information that provides a fundamental understanding of geomorphic processes. In the Yalu River-Wangtian＇e volcanic region of northeastern China, broadly distributed fiat lava terrain provides an ideal site to study the recession of fluvial knickpoints because knickpoints and waterfalls are well preserved here. Here we describe the distribution of knickpoints in the Yalu River-Wangtian＇e volcanic region by combining DEM analysis and numerical modeling Furthermore, we present a knickpoint celerity model, derived from stream-power incision model, to relate knickpoint recession rate to drainage area. We calibrate important empirical coefficients with our knickpoint celerity model; the best fit erosion coefficient （K） is 1.32×10^-8, and the best fit drainage area exponent （m） is 0.69. Error analysis indicates a close correspondence between synthetic and real knickpoints. Finally, we show that knickpoint recession rates in the Yalu River-Wangtian＇e volcanic region are -1-10 mm/a during the early stages of transient incision, and that the present rates are -1-6 mm/a. Our recession rate results are in good agreement with previous findings from the Aso Volcano and volcanoes near Boso Peninsula （Japan）, which have a similar geologic history to the Yalu River-Wangtian＇e volcanic region. Our present effort provides new insight into landscape evolution in the Yalu River-Wangtian＇e volcanic region in northeastern China.Initiation and recession of the knickpoints are significant boundary condition for processes of fluvial system.The distribution and recession rates of knickpoints contain information that provides a fundamental understanding of geomorphic processes.In the Yalu River-Wangtian'e volcanic region of northeastern China,broadly distributed flat lava terrain provides an ideal site to study the recession of fluvial knickpoints because knickpoints and waterfalls are well preserved here.Here we describe the distribution of knickpoints in the Yalu River-Wangtian'e volcanic region by combining DEM analysis and numerical modeling.Furthermore,we present a knickpoint celerity model,derived from stream-power incision model,to relate knickpoint recession rate to drainage area.We calibrate important empirical coefficients with our knickpoint celerity model;the best fit erosion coefficient (K) is 1.32×10 8,and the best fit drainage area exponent (m) is 0.69.Error analysis indicates a close correspondence between synthetic and real knickpoints.Finally,we show that knickpoint recession rates in the Yalu River-Wangtian'e volcanic region are ～1-10 mm/a during the early stages of transient incision,and that the present rates are ～1-6 mm/a.Our recession rate results are in good agreement with previous findings from the Aso Volcano and volcanoes near Boso Peninsula (Japan),which have a similar geologic history to the Yalu River-Wangtian'e volcanic region.Our present effort provides new insight into landscape evolution in the Yalu River-Wangtian'e volcanic region in northeastern China.

关 键 词：Yalu River-Wangtian＇e volcanic region KNICKPOINT knickpoint celerity model landscape evolution 

分 类 号：P343.1[天文地球—水文科学] TN4[天文地球—地球物理学]