In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process ...In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process of flash flood. However, little attention was paid on bearing body of hazard, the clusters of buildings. Thus the real disaster mechanism of flash flood remains unclear.Accordingly, based on the experiments of artificial flash floods in a conceptual solid model, this paper focuses on the flood-impacted inundation characteristics of the building clusters at different locations of the gully model, in order to obtain a better understanding of the disaster process and the interaction between the flash floods and building clusters. The results showed that, in a typical smallscale flash flood gully with hot and dry climate, 1)clusters of buildings on an alluvial fan could reduce about 35% of the flooding area by blocking the diffusion of the flood to the depression areas, and could also promote the deposition in lower reaches of the river channel by blocking the overbank flow from going back into the channel, making the width-depth ratio of the channel larger. 2) The flash flood rates of disaster and hazard on the alluvial fan are generally higher than that of the inner gully. For the inner gully,buildings located on the beaches along the lower river and the transitional areas of the straight channel and channel bends can easily be affected because of their lower elevations. For the alluvial fan, buildings nearby the meanders suffer the greatest impacts because of bank collapsing and flooding. 3) The safe vertical distance from a building to the river channel is 13 m for the buildings in the inner gully under extreme floods. Below this threshold, the smaller the vertical distance is, the greater the risk exposure is. For the buildings on the alluvial fan, especially for the buildings near the concave bank of the top rush point,the horizontal distance is more important, and the safe value is 80 m under extreme floods.展开更多
Eco-geotechnical measures for debris flow mitigation and control have attracted wide attention,but the mitigation effect is lack of quantitative evaluation of coordinated measures.In order to evaluate the debris flow ...Eco-geotechnical measures for debris flow mitigation and control have attracted wide attention,but the mitigation effect is lack of quantitative evaluation of coordinated measures.In order to evaluate the debris flow mitigation effect in the combinations of geotechnical engineering and ecological engineering,this study investigated the different trends of debris flows behaviour based on the sediment deposition on the gully bed and the loose material on the hillslope.Besides,this research proposed a new model involving vegetation coverage,source gravity energy and debris flow volume based on vegetation-erosion model.The new model validated that the debris flow volume was proportional to the gravity energy of gravel and rock fragments on the hillslope and inversely proportional to the vegetation coverage in a dry-hot valley setting.Furthermore,a typical area in the valley of the Xiaojiang River in Yunnan Province,China was quantified with the new model.The results showed that under different gravity energy conditions,the implementation order of check dam construction and afforestation was important for debris flow mitigation.展开更多
基金supported by the Specific Research of China Institute of Water Resources and Hydropower Research (Grant Nos. Fangji 1240)Chinese Ministry of Water Resources (Grant Nos. 201301058 and 20131059)the Basic Research Fund for Central Public Research Institutes (Grant No. CKSF2015010/TB)
文摘In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process of flash flood. However, little attention was paid on bearing body of hazard, the clusters of buildings. Thus the real disaster mechanism of flash flood remains unclear.Accordingly, based on the experiments of artificial flash floods in a conceptual solid model, this paper focuses on the flood-impacted inundation characteristics of the building clusters at different locations of the gully model, in order to obtain a better understanding of the disaster process and the interaction between the flash floods and building clusters. The results showed that, in a typical smallscale flash flood gully with hot and dry climate, 1)clusters of buildings on an alluvial fan could reduce about 35% of the flooding area by blocking the diffusion of the flood to the depression areas, and could also promote the deposition in lower reaches of the river channel by blocking the overbank flow from going back into the channel, making the width-depth ratio of the channel larger. 2) The flash flood rates of disaster and hazard on the alluvial fan are generally higher than that of the inner gully. For the inner gully,buildings located on the beaches along the lower river and the transitional areas of the straight channel and channel bends can easily be affected because of their lower elevations. For the alluvial fan, buildings nearby the meanders suffer the greatest impacts because of bank collapsing and flooding. 3) The safe vertical distance from a building to the river channel is 13 m for the buildings in the inner gully under extreme floods. Below this threshold, the smaller the vertical distance is, the greater the risk exposure is. For the buildings on the alluvial fan, especially for the buildings near the concave bank of the top rush point,the horizontal distance is more important, and the safe value is 80 m under extreme floods.
基金supported by the National Natural Science Foundation of China(41790434 and 41907229)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0903)+2 种基金Chinese Academy of Sciences(XDA23090401)the National Key R&D Program of China(2018YFC1505201)the Beijing Municipal Education Commission for their financial support through Innovative Trans disciplinary Program“Ecological Restoration Engineering”。
文摘Eco-geotechnical measures for debris flow mitigation and control have attracted wide attention,but the mitigation effect is lack of quantitative evaluation of coordinated measures.In order to evaluate the debris flow mitigation effect in the combinations of geotechnical engineering and ecological engineering,this study investigated the different trends of debris flows behaviour based on the sediment deposition on the gully bed and the loose material on the hillslope.Besides,this research proposed a new model involving vegetation coverage,source gravity energy and debris flow volume based on vegetation-erosion model.The new model validated that the debris flow volume was proportional to the gravity energy of gravel and rock fragments on the hillslope and inversely proportional to the vegetation coverage in a dry-hot valley setting.Furthermore,a typical area in the valley of the Xiaojiang River in Yunnan Province,China was quantified with the new model.The results showed that under different gravity energy conditions,the implementation order of check dam construction and afforestation was important for debris flow mitigation.
