The mudslide refers to a kind of special torrent in mountain valley, inspired by heavy rain, snow water and other water sources and containing a large amount of sediment and rocks. Its feature is that it tends to flare up suddenly and then, feculand fluid rushes down along the steep gully and the ground began shaking and the valley seems to encountr thundering. In a very short time, debris flows can flow a large amount of sediment out of the gully and the sediment will go on the rampage and accumulate in the broad accumulation area, often causing great harm to human libes and property. Landslides often has the characteristics of breaking out suddenly, aggressively and swiftly and may causes collapse, landslides and floods, so the degree of harm is much more extensive and serious than single collapse, landslides and floods.
Its harm to human beings is embodied in the following four aspects:
The harm to residential regions
One of the most common detriments of debris flow is to rush into villages and towns, destroying houses, factories, businesses and other facilities, submerging people and livestock, destroying farmland and even leading to the destruction of the whole village. For example, in August 1969, a mudslide in the south of Nongzhang district in Yingjiang river basin in Yunnan caused the destruction of the two villages of Xinzhang and Lao zhangjin. 97 people were killed and the economy loss reached around a million yuan.
Damage to roads and railways
Debris flow can directly bury stations, railways, roads and destroy roadbed, bridges and other facilities, causing traffic disruption. Besides, it also can cause the overthrow of running train, automobile and result in serious personal casualty accidents.
Sometimes the mudslide flows into the river channel, causing a great change in the channel, indirectly destroying roads, railways and other structural facilities, and even forcing the roads to be diverted, resulting in huge economic losses.
For example, across the cross ditch in GanChuan highway 394000 meters, mudslides hit the area in July 1978, blocking Zilongjiang and submerging roads as long as 1000 meters. The Bailongjiang was rechannelled, making the 2000-meter roadbed become main riverway. In addition, highway, revetment and aqueduct were all destroyed. Since 1962, the line has been rerouted three times due to the impact of mudslides on the other side. Since the founding of the People's Republic of China, landslides have caused untold losses to China's railways and highways.
Damage to Water Resources and Hydropower Engineering
It mainly destroys the hydropower station, the drainage channel and the gully building, the tailwater channel of the hydropower station, and causes the reservoir sedimentation and the erosion of the surface of dams.
Damage to mines
It mainly destroys mines and relative facilities, silts mines tunnels, injures mine personnel, causes stoppage of production, and even destroys mines.
Since the 1980s, the world's major mudslides caused economic losses of hundreds of billions of dollars and hundreds of thousands of casualties. Debris flow in the south bank of the Dadu River in Sichuan province occurred at 1:30 a.m. on July 9, 1981. Landslide destroyed the LiziYida Bridge in Liziyida ditch in the north of ChengKun railway station and blocked Dadu river mainstream in a few minutes, causing Dadu River to cutoff. After 4 hours, debris flow dam collapsed. At 1:46 of the day, a train from Geliping to Chengdu loaded with more than one thousand passengers, encountering mudslides in Nainaibao tunnel in the south of bridge, with the speed of over 40 kilometers per hour. The locomotive and a few carriages before fell into the Dadu River.
After subsequent statistics, more than 300 people were killed and 146 injured and ChengKun rail line was blocked for 372 hours, causing direct economic loss of 2000 ten thousand yuan. The disaster is one of the most serious train accident caused by debris flow in world railway history.
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