Debris Flow Hazard
Journal of Natural Disasters,2017,Vol 26,No. 03
【Abstract】 Hexi corridor is the golden area and link of Silk Road Economic Belt, and has special location and important status. Based on geological disaster report data of Gansu Province and combined with landform, hydrology, soil and vegetation of Hexi Corridor, this paper selects seven environmental variables including elevation standard deviation, slope, content of clay and sand particles in 0–100 cm deep surface, precipitation from May to October, river network density and vegetation coverage, builds spatial distribution layer of debris flow gully development samples and environment variables pattern by GIS technology, constructs debris flow disaster hazard MaxEnt distribution model of Hexi Corridor, predicts debris flow disaster hazard distribution probability (P) of Hexi Corridor, divides hazard levels, completes mapping debris flow disaster hazard assessment for Hexi corridor, and analyzes contribution rate of each environmental variable to distribution probability P and corresponding response curves. Result shows that the values P are between 0–0.95; the areas of extremely high-level hazard zone (0.5 ≤ P ≤ 0.95), high-level hazard zone (0.2 ≤ P < 0.5), middle-level hazard zone (0.09 ≤ P < 0.2) and low-level hazard zone (0 ≤ P < 0.09) are about 2.57 × 104 km2, 4.11 × 104 km2, 4.90 × 104 km2 and 14.32 × 104 km2, respectively, and account for 9.92%, 15.87%, 18.92% and 55.29% of the total area of Hexi Corridor.
Risk assessment of debris flow disaster: a case study of Wudu District in the south of Gansu Province, China
Journal of Natural Disasters,2016,Vol 25,No. 06
【Abstract】 Taking Wudu District in the south of Gansu Province as research object, and selecting 25 villages and towns in the district as assessment unit, the regional risk assessment was carried out by using regional hazard and vulnerability as basic assessment indices. The regional hazard was integrated through historical disaster data and field investigation data. At the same time, information method was adopted and 250 m × 250 m basic grid was selected as assessment unit, and then the hazard was obtained. Taking the exposure, the sensitivity and the recovery ability of hazard-affected body into account, with the help of DEA model and C-D function, the vulnerability values of villages and towns in Wudu District were calculated, and then the vulnerability subregion of villages and towns in research region was obtained. Hazard and vulnerability were coupled, and the regional risk coefficient was introduced, and then the risk assessment model was established, based on the risk rank and the risk zoning map of Wudu district which were obtained by using GIS technology. Meanwhile, some suggestions were proposed for disaster prevention and mitigation. The results show that the extremely high risk areas in Wudu district were mainly distributed in the Chengguan Town, Dongjiang Town, Majie Town, Bolin Village, Anhua Town and most parts of Hanwang Town.
Hazard regionalization of debris flow disasters along highways based on genetic algorithm and cloud model
Chinese Journal of Rock Mechanics and Engineering,2016,Vol 35,No. 11
【Abstract】 Hazard regionalization of debris flow disasters along highways clarifies the priorities of disaster prevention and protection standards for different parts of China and provides a theoretical basis for macro policy formulation. Hazard sources of debris flow disasters along highways were identified from four aspects of the topography and landscape, precipitation, rock and soil materials, and vegetation. The hazard assessment indexes were extracted using the genetic algorithm according to the survey results of the potential debris flow disasters along highways. The weight of each index was calculated through the AHP algorithm improved by the cloud model. The assessment index maps were rendered and the spatial hazard analysis of debris flow disasters along highways was made with Arc GIS. The hazard regionalization scheme of debris flow disasters along highways in China was worked out mainly based on a hazardous degree. The hazardous degree of debris flow disasters along highways in China is from 1.000 to 7.900. High hazardous areas are the mountainous areas in the southeast of Zhejiang and Fujian Province, the mountain areas of Taiwan, Kunlun Mountains, Tianshan Mountains, Taihang Mountains, Loess Plateau, Hengduan Mountains, and eastern Tibetan Plateau. China is divided into regions of low hazard, moderate hazard, severe hazard, and extremely severe hazard. The extremely severe hazard areas are the Loess Plateau–Qinba mountain areas, Wuyi Mountain–Taiwan mountain areas, Sichuan-Yunnan mountain areas, and Tianshan–Kunlun mountain areas.
A Debris Flow Hazard Monitoring and Early Warning System Based on Formation and Motion Processes of Debris Flow
Journal of Natural Disasters,2014,Vol 23,No. 03
【Abstract】 According to the massive total volume, group-occurring debris flows in the Wenchuan earthquake stricken area, the monitoring and early warning system will be an economic and effective measure. Based on analysis of past performance of debris flow early warning and existing problems, this paper proposed a new debris flow hazard monitoring and early warning system based on the formation and motion mechanism of debris flow. The new system consists of rainfall monitoring, fluid level monitoring, pore-water pressure monitoring, soil moisture monitoring, ground vibration monitoring, and video monitoring. And the early warning levels were established after the comprehensive analysis of the threshold values of all these monitorings. It would be suitable to use this comprehensive monitoring and early warning system for protecting debris flow threatened areas in the Wenchuan earthquake stricken area.