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The weather process experienced three heavy rainfalls and formed two heavy rainstorms and one extra heavy rainstorm on June 14, June 18 and June 23. Rain recorders from June 14 to June 18, 2010 showed that the average rainfall in the county was 335.7mm, which was 268mm more than in the same period of the previous calendar year, and the average rainfall in the severely affected areas was 399.5mm, which was 332mm more than the same period of the previous year. Affected by high and low troughs and low-level vortex shedding, the continuous heavy rain weather continued until the 25th. On the 13th, from 20:00 to 25:00, Shunchang had more than 50% of the township's process rainfall exceeding 620mm, and the urban rainfall was 739.3mm, which was the largest. The maximum rainfall in June of the past 50 years was 2.6 times the average rainfall in June. Among them, heavy rains occurred on the 14th, the daily rainfall was 107.6mm, and the rainfall on day 18 was 269.1mm. The distribution characteristics of precipitation in each period. On June 18th, Shuangxi Town, Dagan Town, Yuankeng Town, Yangzheng Town, Zhengfang Township, etc., with large-scale, large-scale landslides, collapses, and mudslides, all occurred. From 5 am to 17 o’clock on that day, precipitation exceeded 12 h. 200mm, the largest urban rainfall is 250mm. Tianping Village of Yangkou Town is the center of the heavy rainstorm. Due to the complex geological environment of this village, it became the most severe landslide of “6.18†landslides and debris flows. The entire village was razed to the ground.
Natural factors: The type, structure and surface conditions of rock and soil determine the probability and development of geological disasters. Heavy rain is the main cause of geological disasters. Under certain geological structure and environmental conditions, the process precipitation intensity and precipitation duration are the most important precipitating factors for geological disasters. According to statistics, geological disasters caused by heavy rain accounts for more than 95% of the total. The type of rainstorm that triggers geological disasters mainly includes sudden rainstorms and persistent rainstorms. Sudden rainstorms during the course of persistent rainstorms are the main inducing factors of geological disasters. In the late spring and early summer seasons, southwestern warm and humid air currents are often active, and low-level southwest rapids prevail, forming heavy rain or continuous heavy rain; heavy rainstorm concentrated areas are often areas where geological disasters such as landslides, collapses, mudslides, and ground collapse occur. Human factors: Human-caused disasters mainly include inappropriate land reclamation, deforestation and vegetation destruction, loss of protection of slopes, loose soil, increased infiltration of surface water, induced collapse, and landslides; , easy to cause landslides and mudslides; build artificial slopes by building slopes and building traffic routes, etc., to form artificial slopes with high cutting slopes, steep slopes, loss of support at the lower part of the slope, and decline; building of buildings, construction of factories, and heaps on slopes. Filling the earth, so that the slope loses its balance and slides along the soft surface, it is easy to induce collapse and landslide in the continuous rainstorm.
The occurrence of geological disasters such as landslides, collapses, and mudslides is closely related to the accumulated precipitation and short-term heavy rainfall in the previous period. Through the records of small-scale weather stations for seven consecutive days, under the conditions of sufficient precipitation in the previous period, there were ignited torrential rains that triggered geological disasters. The possibility is great. The relationship between geological disasters and pre-precipitation and precipitation on the same day includes three types: sudden heavy rainfall, continuous heavy rain, rainstorm induced, and typhoon-induced rain. A comprehensive analysis of the circulation background, water vapor conditions, physical quantity fields, and mesoscale features from June 13th, 2010 to June 18th, 2010 found that the continuous storm weather process was mainly affected by low-level low-vortex shear and low-level jets. In addition, the favorable conditions of heat and power are provided by the continuous low-level energy instability and strong upward movement. Sustained heavy rainfall requires large amounts of water vapor transport and strong convergence over the precipitation area. For stormy weather, if there are heavy rain events, there must be sufficient sources of water vapor and water vapor to converge in strong precipitation areas. Continuous heavy precipitation requires a large amount of water vapor to transport and it strongly converges above the precipitation area. Analysis of the water vapor flux and moisture flux divergence field can determine these water vapor variations. The water vapor flux at 850hpa from 08:00 to 18:00 on June 17th, Fujian Province was in a large value area; analysis of the 850hpa water vapor flux divergence field at that time, Fujian Province was in the center of a negative value zone, from June 17th. The water vapor began to increase rapidly and the value was -10-20 and 10.7g•s-1•cm-2•hpa-1. It controlled the southern part of Nanping City, indicating that the water vapor convergence is very strong in this area and it is very favorable for water vapor. The convergence of the area will increase the strong precipitation in the area, providing sufficient water vapor conditions for the occurrence of excessive precipitation on June 18 in Shunchang County.
The special terrain (geography) is the geological factor and topographical condition of the "6.18" super landslide, collapse, mudslide and other geological disasters. The continuous heavy rainfall weather process is the main weather condition for the geological disasters such as the “6.18†super landslide and debris flow. The pre-precipitation and the torrential rain that triggered the day were the causes of the “6.18†geological disaster. Before the occurrence of rare continuous heavy precipitation, the 500hpa low trough in the eastern Ural continued to be stable, providing favorable circulation conditions for the cold air intrusion to the southeast, and the low-level jet combined with the low-level low vortex shear is the main weather that caused this continuous heavy rainfall event. situation. Under the effect of special terrain uplift, strong convective instability and vertical ascent movements are generated, which provide favorable water vapor conditions and dynamic conditions for the occurrence of heavy rainfall.
Sustained rainfall is the main cause of natural disasters in some regions
Analysis of meteorological conditions of the geological disasters in Shunchang, Fujian Province Shunchang is located in northern Fujian. Its geographic location and special climatic conditions have caused Shunchang to become a geological disaster-prone area. Continual rainstorms are prone to landslides, landslides, mudslides and other geological disasters. On June 18, 2010, a torrential rain in Shunchang County triggered landslides, collapses, mudslides and other geological disasters that caused floods in 17 towns and villages in 12 counties across the county. Two people died in the disaster, 12 people were missing, and 1182.3 were collapsed and damaged. Communications, communications Interrupted, the direct economic loss was 1.546 billion yuan. The author used small meteorological stations, rainfall recorders, etc. to conduct a comprehensive study on the circulation background, water vapor conditions, physical quantity fields, and mesoscale features of the disaster, resulting in the meteorological causes of the geological disasters, so as to improve the meteorological monitoring and early warning capabilities of mountainous regions.