TY - JOUR
T1 - Channel adjustment after artificial neck cutoffs in a meandering river of the Zoige basin within the Qinghai-Tibet Plateau, China
AU - Li, Zhiwei
AU - Gao, Peng
N1 - Funding Information:
This study has been supported by the National Natural Science Foundation of China (91547112, 91647204, 91647118, and 51709020), and the Open Project of State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, China (2017-KF-01), the Project of Qinghai Science & Technology Department, China (2016-ZJ-Y01, 2016-HZ-802), Natural Science Foundation of Hunan Province, China (2018JJ3547), and Changsha Science and Technology Plan Project, China (kq1701075). The second author was also partially supported by the Appleby-Mosher fund of Maxwell School of Citizenship and Public Affairs, Syracuse University. We thank Professor Zhaoyin Wang and Professor Xuyue Hu for their support of our field survey in 2013-2014 and in 2016-2017, respectively. We also thank Xiongdong Zhou, Liqun Lv, Lijian Qi, Jing Liu, and Xiang Li for their field assistance and Xinyu Wu for partly helping us process data. Finally, we like to thank Kory Konsoer and another reviewer for providing thoughtful critiques and suggestions.
Funding Information:
This study has been supported by the National Natural Science Foundation of China ( 91547112 , 91647204 , 91647118 , and 51709020 ), and the Open Project of State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University , China ( 2017-KF-01 ), the Project of Qinghai Science & Technology Department , China ( 2016-ZJ-Y01 , 2016-HZ-802 ), Natural Science Foundation of Hunan Province , China ( 2018JJ3547 ), and Changsha Science and Technology Plan Project , China ( kq1701075 ). The second author was also partially supported by the Appleby-Mosher fund of Maxwell School of Citizenship and Public Affairs, Syracuse University . We thank Professor Zhaoyin Wang and Professor Xuyue Hu for their support of our field survey in 2013-2014 and in 2016-2017, respectively. We also thank Xiongdong Zhou, Liqun Lv, Lijian Qi, Jing Liu, and Xiang Li for their field assistance and Xinyu Wu for partly helping us process data. Finally, we like to thank Kory Konsoer and another reviewer for providing thoughtful critiques and suggestions.
Publisher Copyright:
© 2018
PY - 2019/1
Y1 - 2019/1
N2 - Neck cutoff is an essential process that significantly changes the morphodynamic characteristics of a meandering bend. In reality, however, observing natural processes of a neck cutoff is very difficult. In this study, we artificially triggered neck cutoffs by excavating a 0.4 m (width) × 0.5 m (depth) ditch to connect the beginning and ending of two highly convoluted bends along a meandering tributary of the upper Black River, a major tributary of the Upper Yellow River situated in the northeastern side of the Qinghai-Tibet Plateau in China. Our morphologic and hydraulic measurements in summers of 2013, 2014, 2016, and 2017, the subsequent hydraulic-geometry analysis, and three-dimensional simulation showed that both artificial ditches expanded fast to the size comparable to the former channel in a three-year period and the oxbow channel was disconnected from the former channel quickly, though sediment supply may be limited in this area. The morphological adjustment was featured by (1) distinct temporal trends of the development of the width/depth ratio between the two cutoff channels, (2) different diversion factors of the total discharge to the cutoff channel, and (3) diverse interaction patterns between cutoff and former channels. These discrepancies were supported by simulated different three-dimensional velocity distributions in the two cutoff channels, suggesting the importance of the clustered local velocities. Comparing these results with those reported in earlier studies showed that besides channel slope, unit stream power, and bank strength, the diversion angle between the cutoff and former channel played an important role in controlling channel adjustment. The discrepancy of the adjustment processes between the cutoff channel in this study and those in two previous ones revealed that channel adjustment after neck cutoff behaved differently under different physical settings and require more field-based studies.
AB - Neck cutoff is an essential process that significantly changes the morphodynamic characteristics of a meandering bend. In reality, however, observing natural processes of a neck cutoff is very difficult. In this study, we artificially triggered neck cutoffs by excavating a 0.4 m (width) × 0.5 m (depth) ditch to connect the beginning and ending of two highly convoluted bends along a meandering tributary of the upper Black River, a major tributary of the Upper Yellow River situated in the northeastern side of the Qinghai-Tibet Plateau in China. Our morphologic and hydraulic measurements in summers of 2013, 2014, 2016, and 2017, the subsequent hydraulic-geometry analysis, and three-dimensional simulation showed that both artificial ditches expanded fast to the size comparable to the former channel in a three-year period and the oxbow channel was disconnected from the former channel quickly, though sediment supply may be limited in this area. The morphological adjustment was featured by (1) distinct temporal trends of the development of the width/depth ratio between the two cutoff channels, (2) different diversion factors of the total discharge to the cutoff channel, and (3) diverse interaction patterns between cutoff and former channels. These discrepancies were supported by simulated different three-dimensional velocity distributions in the two cutoff channels, suggesting the importance of the clustered local velocities. Comparing these results with those reported in earlier studies showed that besides channel slope, unit stream power, and bank strength, the diversion angle between the cutoff and former channel played an important role in controlling channel adjustment. The discrepancy of the adjustment processes between the cutoff channel in this study and those in two previous ones revealed that channel adjustment after neck cutoff behaved differently under different physical settings and require more field-based studies.
KW - Cantilever bank failure
KW - Channel adjustment
KW - Diversion angle
KW - Meandering river
KW - Neck cutoff
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U2 - 10.1016/j.catena.2018.08.042
DO - 10.1016/j.catena.2018.08.042
M3 - Article
AN - SCOPUS:85052898769
SN - 0341-8162
VL - 172
SP - 255
EP - 265
JO - Catena
JF - Catena
ER -