Shang Jie Formation in Matatun Village, Xia Yan Township, Guiding County is located in the southeast of Guiding County, Qiannan Prefecture, Guizhou Province, about 5 kilometers away from Xia Yan Township. Geographical coordinates are: east longitude 107 17' 43 ",north latitude 26 23'11",altitude 1 180m. 20 1 1, 1 A landslide occurred in Shang Jie Formation, Matun Village, Xia Yan Town, Guiding County, with a length of S309m, a width of 150m, a thickness of 5 ~ 15 m, an average thickness of 10m and a volume of 45438. The main reason is that the villagers' houses were built on the hillside and no protective measures were taken after the slope was cut. Since mid-August, the area has been hit by heavy rain for several days, leading to landslides. Due to timely and accurate early warning and forecast, rapid emergency response, effective organization and measures in place, 40 people successfully avoided danger without causing casualties or property losses.
2 Basic environmental background
2. 1 terrain
The landslide area is located in the south of Guizhou Plateau, characterized by valley basins and hilly landforms. The terrain in the area fluctuates greatly, with the highest elevation 1502.5m, the lowest elevation 1 142.6m, the maximum relative height difference of 359.9m and the slope of 30 ~ 50.
2.2 Formation lithology
Karst landform is developed in the landslide area, and the exposed stratum is Quaternary (Q) residual slope product, which contains sandy clay and loam. Upper Devonian Yaosuo Formation (D3y) dolomite, with argillaceous upper part and limestone top; Upper Devonian Wangchengpo Formation (D3w) dolomite mixed with a small amount of limestone; Dolomite, limestone, sandstone and shale of Devonian Dushan Formation (D2d); The Devonian system is the middle-thick timely sandstone of Shangshangzhai Formation (D2b).
2.3 Hydrogeology
According to the analysis of stratum lithology, water-bearing medium and groundwater dynamic conditions exposed in the landslide area and its adjacent areas, the groundwater types in the area are mainly pure carbonate karst water, clastic rock fissure water and loose rock pore water. Groundwater is mainly replenished by atmospheric precipitation through karst; Carbonate karst water and bedrock fissure water are mainly supplied by infiltration and discharged into gullies or low-lying areas cut by topography.
2.4 Meteorology and Hydrology
The landslide area belongs to a typical warm and humid monsoon climate in the middle subtropical zone, with four distinct seasons, abundant heat, abundant rainfall, abundant clouds, small temperature difference and mild climate. Average temperature 15℃, average rainfall1100 ~1400 mm, with no severe cold in winter and no severe heat in summer. In the hottest month (July), the average temperature is 24.3 ~ 28.3℃, and the average temperature difference is15.1~17.3℃. Average annual rainfall 12 17.5mm, maximum annual rainfall141.7mm, minimum annual rainfall1158.3mm. The main surface water system in the landslide area is Guti River. Other surface water systems are mostly seasonal rivers, belonging to the Wujiang River system in the Yangtze River basin.
2.5 Human engineering activities
There are three houses under construction near the landslide, and the cutting of the front edge is unreasonable, forming a high and steep slope. Without effective treatment measures, the shear strength of rock and soil is significantly reduced, resulting in mountain cracks and landslides after heavy rain.
Figure 1 Buildings and high-voltage transmission towers threatened by landslides
Fig. 2 shear outlet of landslide front
3 Monitoring and emergency hedging
3. 1 Monitoring and early warning
Guiding county has formulated a geological disaster inspection and monitoring system, and implemented the principle of "whoever is threatened is responsible for monitoring". The villagers in this group are responsible for the daily inspection and monitoring of this hidden danger point, observing the deformation and damage of the landslide and its macro precursors, and recording the monitoring points, time, monitoring data and monitoring personnel of each inspection and monitoring in detail. Since mid-August, there have been heavy rains for several days, and the monitoring personnel have strengthened their monitoring. On August 15, the monitoring personnel found that the foundation of the construction building of Shang Jie Formation in Matun Village was cracked, and many cracks with a width of 3 ~ 10 cm appeared on the ground, and the front edge of the landslide had shear displacement, which was in danger of slipping at any time. After the monitoring personnel found the danger, they immediately reported it to Yanxiaxiang Land Office. After receiving the report, the Land Office immediately reported to Yanxiaxiang People's Government and Guiding County Land and Resources Bureau, and at the same time started the early warning mechanism, and issued a landslide warning to the residents of Shang Jie Group who were threatened by danger near the hidden danger point.
Fig. 3 The trailing edge of landslide collapses.
Figure 41:1ten thousand landslide plan
Figure 51∶ 50,000 Landslide Topographic Geological Map
3.2 Emergency hedging
After receiving the dangerous situation report, the relevant leaders of Guiding County Land and Resources Bureau and Yanxiaxiang People's Government immediately rushed to the scene, demanding that the construction of three houses in Shang Jie Group threatened by landslide should be stopped immediately, and the nearby villagers should be evacuated urgently for proper resettlement. In addition, dangerous areas shall be designated, and protective fences and warning signs shall be set up in the areas to prevent people and animals from entering into the wrong places and causing casualties and property losses. On August 18, a landslide occurred. After receiving the disaster report, Guizhou Geological Environment Monitoring Institute immediately organized professional technicians to arrive in Guiding County at noon on August 19, and together with the staff of Guiding County Land and Resources Bureau, conducted an emergency investigation on the disaster site and took corresponding emergency measures.
4 Experience and Enlightenment
(1) Party committees and governments at all levels attach great importance to it and make careful arrangements, which is the prerequisite for the prevention and control of geological disasters.
At the beginning of the flood season, in response to a heavy rainfall, the Qiannan government organized various departments to hold an emergency flood control meeting, requiring all departments to do a good job in flood control and disaster prevention in time. Guiding county party committee and county government earnestly implemented the "four in place" system, which laid a good foundation for landslide disaster emergency avoidance.
(2) The solid work of land and resources departments and relevant departments is the key to the prevention and control of geological disasters.
First, the responsibility for disaster prevention is implemented at the grassroots level. Before the flood season, the Land and Resources Bureau of Guiding County implemented the responsibility of disaster prevention for all hidden dangers to people, and signed letters of responsibility at different levels to form a group prevention and treatment system. Second, the basic work of disaster prevention is in place. Make a feasible emergency plan, resolutely implement the 24-hour duty system, find dangerous situations and respond quickly. Third, early warning and forecasting are timely and accurate. The accurate forecast of Guizhou Geological Environment Monitoring Institute and the accurate early warning of monitoring personnel are important guarantees for this successful hedging.
(3) Mobilizing the masses to take the initiative to prevent disasters is fundamental to the prevention and control of geological disasters.
First, do a good job in publicizing disaster prevention knowledge. From March to May, Guiding County carried out roving publicity and training activities on the prevention and control of geological disasters in the rural areas of Qiannan 12 counties and cities, and widely publicized the knowledge on the prevention and control of geological disasters by distributing publicity materials, posting pictures, playing videos, and giving on-site explanations, so that the knowledge on the prevention and control of geological disasters was widely popularized. The second is to do emergency drills. Before the disaster, the land and resources department of Guiding County organized a geological disaster emergency avoidance drill in nearby towns and villages, which improved the people's awareness of disaster prevention and emergency avoidance ability, and played a vital role in this successful avoidance.
(This part of basic information is provided by Guizhou Provincial Department of Land and Resources and edited by Chu Hongliang)