Vol18 No.9: 2427-2440
【Title】Geomorphic effect of debris-flow sediments on the Min River, Wenchuan Earthquake region, western China
【Author】HU Xu-dong1*; ZHOU Li-qin2,3,4; LIU Wei-ming2,3; WANG Hao2,3; CUI Lei5
【Addresses】1 College of Civil Engineering & Architecture, China Three Gorges University, Yichang 443002, China; 2 Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu 610041, China; 3 Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; 4 University of Chinese Academy of Sciences, Beijing 100049, China; 5 China Renewable Energy Engineering Institute, Beijing 100049, China
【Corresponding author】HU Xu-dong
【Citation】Hu XD, Zhou LQ, Liu WM, et al. (2021) Geomorphic effect of debris-flow sediments on the Min River, Wenchuan Earthquake region, western China. Journal of Mountain Science 18(9). https://doi.org/10.1007/s11629-021-6816-1
【Abstract】Coseismic landslides and subsequent mobilization of sediment greatly aggravated the landscape evolution and river sedimentation after the Wenchuan earthquake. The debris-flow alluvial fan and river morphological index was combined to describe quantitatively the effects of debris-flow sediment on the river characteristics in Longmen Mountains. The section of the Min River from the urban area of the Wenchuan county to the epicenter, the Yingxiu town in this county, was selected as the study area. We identified 27 river-blocking debris-flows (5 partial-, 7 semi-, 7 over semi-, and 5 fully-blocking degrees) in the study area via remote sensing interpretation and field survey. Based on this, the response of river longitudinal profile and curvature to debris-flow sediment was qualitatively and quantitatively analyzed. The results show that the channel gradient has decreased due to debris-flow aggradation, while two marked peaks in the river steepness index (ksn, represents therelative steepness degree of the channel) changed from 585 m0.9 to 732 m0.9 in zone 1, from 362 m0.9 to 513 m0.9 in zone 2. Moreover, the main channel has undergone substantial lateral migration with channel width decreased and river curvature increased. The temporal and spatial variation between rivermorphological characteristics and debris-flow sediments in short-term provides insights into the internal dynamic role of mass wasting processes in river morphology, which could be served as useful information for natural hazards management to prevent the river from being blocked by episodically debris flows after the earthquake.
【Keywords】Debris-flow sediment; Longitudinal profile; River curvature; Min River; Wenchuan earthquake