標題: A case of rapid rock riverbed incision in a coseismic uplift reach and its implications
作者: Huang, Ming-Wan
Pan, Yii-Wen
Liao, Jyh-Jong
土木工程學系
Department of Civil Engineering
關鍵字: Coseismic uplift;Incision rate;Taan River;Chi-Chi earthquake;Taiwan
公開日期: 15-二月-2013
摘要: During the 1999 Chi-Chi earthquake (M-w = 7.6) in Taiwan, the coseismic displacement induced fault scarps and a pop-up structure in the Taan River. The fault scarps across the river experienced maximum vertical slip of 10 m, which disturbed the dynamic equilibrium of the fluvial system. As a result, rapid incision in the weak bedrock, with a maximum depth of 20 m, was activated within a decade after its armor layer was removed. This case provides an excellent opportunity for closely tracking and recording the progressive evolution of river morphology that is subjected to coseismic uplift. Based on multistaged orthophotographs and digital elevation model (DEM) data, the process of morphology evolution in the uplift reach was divided into four consecutive stages. Plucking is the dominant mechanism of bedrock erosion associated with channel incision and knickpoint migration. The astonishingly high rate of knickpoint retreat (KPR), as rapid as a few hundred meters per year, may be responsible for the rapid incision in the main channel. The reasons for the high rate of KPR are discussed in depth. The total length of the river affected by the coseismic uplift is 5 km: 1 km in the uplift reach and 4 km in the downstream reach. The downstream reach was affected by a reduction in sediment supply and increase in stream power. The KPR cut through the uplift reach within roughly a decade; further significant flooding in the future will mainly cause widening instead of deepening of the channel. (C) 2012 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.geomorph.2012.11.022
http://hdl.handle.net/11536/21434
ISSN: 0169-555X
DOI: 10.1016/j.geomorph.2012.11.022
期刊: GEOMORPHOLOGY
Volume: 184
Issue: 
起始頁: 98
結束頁: 110
顯示於類別:期刊論文


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