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:
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."