Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating land...Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides.展开更多
Climate change in the Arctic region is more rapid than that in other areas owing to Arctic amplification. To better understand climate change and the driving mechanisms, long-term historical reconstructions throughout...Climate change in the Arctic region is more rapid than that in other areas owing to Arctic amplification. To better understand climate change and the driving mechanisms, long-term historical reconstructions throughout the Holocene and high-resolution records of the past few hundred years are required. Intense anthropogenic activities in the Arctic have had a great impact on the local environment. Here, we review the Holocene climate change record, responses of the ecosystems to climate change, and the anthropogenic impacts on the environment based mainly on Chinese research from Ny-Alesund. Climate reconstruction studies from Svalbard have revealed several cold episodes during the Holocene, which are consistent with ice rafting events in the North Atlantic region and glacier activity from Greenland, Iceland, and Svalbard. The ecosystem also showed corresponding responses to climate change, especially during the late Holocene. Over recent decades, anthropogenic activities have caused serious pollution and deterioration to the local environment in Svalbard in areas frequented by people. Greater environmental protection is therefore needed to reduce the anthropogenic impacts on the local environment.展开更多
Palaeo-notch sediment, accumulated in lacustrine environment, is a reliable proxy material for palaeoclimatic and palaeoenvironmental research. In this study, we collected a palaeo-notch sediment profile from the Blom...Palaeo-notch sediment, accumulated in lacustrine environment, is a reliable proxy material for palaeoclimatic and palaeoenvironmental research. In this study, we collected a palaeo-notch sediment profile from the Blomstrandhalv?ya, used multiple geochemical proxies to reconstruct palaleoproductivity variations, and investigated their link to climatic records from surrounding regions. C/N atomic ratios and carbon isotope indicate that organic matter in the sediment is mainly derived from lacustrine algae. Toward the surface sediment, the TOC, TN, P contents and the reconstructed palaeoproductivity show remarkable fluctuations with several peaks and troughs, opposite to the variation trend of the CaCO3 contents. Changes in the reconstructed palaeoproductivity are in good agreement with palaeoclimatic records from the surrounding regions, and three interruptions are likely linked to the well-known cooling periods around 1900 BP, 2800 BP and 4200 BP. Thus palaeoproductivity variations on the Blomstrandhalv?ya are mainly driven by climate changes; palaeoproductivity increase during warmer periods, and vice versa. This study will help the research of Arctic lake ecosystem and its response to climate change.展开更多
基金supported by the National Natural Science Foundations of China(grant numbers U22A20601 and 52209142)the Opening fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(grant number SKLGP2022K018)+1 种基金the Science&Technology Department of Sichuan Province(grant number 2023NSFSC0284)the Science and Technology Major Project of Tibetan Autonomous Region of China(grant number XZ202201ZD0003G)。
文摘Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides.
基金supported by the Chinese Polar Environment Comprehensive Investigation and Assessment Program (Grant nos. CHINARE2017-02-01, CHINARE2017-04-04, and CHINARE 2017-04-03)
文摘Climate change in the Arctic region is more rapid than that in other areas owing to Arctic amplification. To better understand climate change and the driving mechanisms, long-term historical reconstructions throughout the Holocene and high-resolution records of the past few hundred years are required. Intense anthropogenic activities in the Arctic have had a great impact on the local environment. Here, we review the Holocene climate change record, responses of the ecosystems to climate change, and the anthropogenic impacts on the environment based mainly on Chinese research from Ny-Alesund. Climate reconstruction studies from Svalbard have revealed several cold episodes during the Holocene, which are consistent with ice rafting events in the North Atlantic region and glacier activity from Greenland, Iceland, and Svalbard. The ecosystem also showed corresponding responses to climate change, especially during the late Holocene. Over recent decades, anthropogenic activities have caused serious pollution and deterioration to the local environment in Svalbard in areas frequented by people. Greater environmental protection is therefore needed to reduce the anthropogenic impacts on the local environment.
基金supported by Chinese Polar Environment Comprehensive Investigation&Assessment Programs(Grant nos.CHINARE2017-02-01,CHINARE2017-04-04)
文摘Palaeo-notch sediment, accumulated in lacustrine environment, is a reliable proxy material for palaeoclimatic and palaeoenvironmental research. In this study, we collected a palaeo-notch sediment profile from the Blomstrandhalv?ya, used multiple geochemical proxies to reconstruct palaleoproductivity variations, and investigated their link to climatic records from surrounding regions. C/N atomic ratios and carbon isotope indicate that organic matter in the sediment is mainly derived from lacustrine algae. Toward the surface sediment, the TOC, TN, P contents and the reconstructed palaeoproductivity show remarkable fluctuations with several peaks and troughs, opposite to the variation trend of the CaCO3 contents. Changes in the reconstructed palaeoproductivity are in good agreement with palaeoclimatic records from the surrounding regions, and three interruptions are likely linked to the well-known cooling periods around 1900 BP, 2800 BP and 4200 BP. Thus palaeoproductivity variations on the Blomstrandhalv?ya are mainly driven by climate changes; palaeoproductivity increase during warmer periods, and vice versa. This study will help the research of Arctic lake ecosystem and its response to climate change.
