Because of the development of industrial and agricultural production, the degree and scale of human's usage of natural resources are also developing. When human economic a ctivities violate the laws of nature, it is bound to trigger the revenge of nature. It is because the unreasonable exploitation of resoures that some debris flows occurs.
In recent years, the number of mudslides induced by human factors is increasing. The human engineering economic activities that may induce debris flow mainly include the following aspects:
Unreasonable excavation
The construction of railways, roads, canals and other engineering structures causes unreasonable excavation. Some of the mudslides were formed when the constructions roads, canals, railways and other constructions disrupt the surface of slopes.
For example, the Laogan ditch from Dongchuan to Kunming road in Yunnan province caused the destruction of the mountain body due to the repair of roads and canals. Besides, because of the earthquake of Xiniu Mountain in 1966 caused collapse and landslide, the mudslide became more serious. What’s more, Hong Kong has built many large engineering and ground buildings for many years and almost for every project, people had to filled sea with mountain soils to get proper building sites.
A rainstorm in 1972 killed 120 people at the construction site because of mudslide caused by landslide.
Unreasonably disposed mineral slag and soil
There are many examples of these kinds of behavior. For example, in LuGu iron ore and Hanluo ditch in Mianning County, Sichuan, a rainstorm in 1972 caused mine debris flow due to the unreasonably disposed mineral slag and soil. The disaster caused solid material of about 100000 steres to rush out of the mountain, burying ChengKun railway for 300 meters and XiXi highway for 300 meters, interrupting driving and causing serious loss of traffic transportation.
In addition, in the neigbourhood of Xishui, Ganchuan railway, people mined in the trench along the highway in 1973. However, there was a mudslide on July 18, 1974, which blocked 15 bridges.
Deforestation and disorder felling
Deforestation will make the vegetation disappear, the slope lose protection, the soil become losse and gully form, which increases the sharply water loss and soil erosion. Therefore, the stability of the slope will be destroyed and collapse, landslide and other bad geological phenomena may occur, so landslides are very likely to happen.
For example, the middle reaches of Bailong River in Gansu province is now a famous mudslide area in China. However, more than a thousand years ago, the bamboo trees were luxuriant and beautiful, the water was clear and the mountains were lush. Unfortunately, the forest was destroyed because of logging and burning coal. So the mudslides easily happen there.
Another example is the great ear head of Gangchuan highway, which was originally a forest area. Because of deforestation, the consequent landslide in 1976 destroyed villages and highways in the downstream, causing serious loss of people's life and property. The local people said, "If the mountains are destroyed, the area under the foot of the mountain will be destroyed, too."
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