How did the catastrophic mudslide break out in Zhouqu, Gansu? What is the reason for it

The place where the mudslide happened this time was in Zhouqu County, and the time was about 10 in the afternoon.

Shandagou is deep, two mountains are sandwiched by a river, and a town is built on the floodplain, which is the basic topographic structure of Zhouqu County, Gannan Prefecture, Gansu Province. Zhouqu debris flow is poured into the county from the towering Beishan Canyon.

Zhouqu is called "Jiangnan of Gansu" because of its rich virgin forest. Since 1950s, the forest coverage rate has dropped from 67% to 20%. 198 1 year, a serious mudslide disaster occurred in Zhouqu. Since 1985, the amount of logging has been decreasing and the afforestation plan has been strengthened. However, due to perennial drought and previous deforestation, the yield of newly planted trees is very low.

Since 200 1, Zhouqu has started to build Daxing Hydropower Station on Bailong River and its tributaries. However, if we want to bomb the hydropower station for land acquisition, it will loosen the rock mass, destroy the vegetation, and cause new landslides. The river channel will be blocked with waste slag and piled up randomly in the river channel to provide loose solid materials for debris flow. At the same time, gold mining is also closely followed.

According to Southern Weekend, the occurrence of debris flow is related to weather forecast. The weather forecast that day said that the rainfall in Zhouqu County was about 10mm, which was also consistent with the actual situation, but the rainfall in the mountainous area reached more than 90 mm that day! Although someone was on duty in the relevant area, it was not reported because the rainfall in this area was not outstanding. When the mudslide was discovered, Zhouqu County had lost power and could not be contacted.

One factor to consider is the time of the disaster. It was afternoon 10, and everyone in the small county should have gone to bed, and there was not much rainfall in the county at that time. Of course, they will think that nothing will happen.

In addition, debris flow and flood damage buildings differently. Debris flow is a huge soil flow mixed with sand and gravel, and buildings are knocked down by impact, not damaged by soaking. It is precisely because of the soil flow that people are buried firmly, and people can't breathe, causing a lot of deaths in an instant. So, you see, the number of people affected is small, but there are many deaths, which is very different from the earthquake and flood.