What causes mudslides that occur frequently during the rainy season?

In mountainous valleys, disasters caused by special torrents containing a large amount of solid detritus such as sediment and stones, and with strong impact and destructive effects, are triggered by heavy rainfall, a large amount of ice and snow meltwater, or rapid surface runoff after the collapse of rivers, lakes, and reservoirs.

The activity intensity of debris flow is mainly related to topography, geological environment and hydrometeorological conditions. Rock fragmentation and deep weathering in areas of collapse, landslide and rock pile community can easily become the source of recharge of solid matter in debris flow. The length of the valley is large, the catchment area is large, and the longitudinal slope is steep, which can provide conditions for the flow of debris flow. Hydrometeorological factors directly provide hydrodynamic conditions. The formation of debris flow must meet the following three conditions at the same time, namely, steep terrain and landform that are convenient for water collection and collection; abundant loose matter; A large amount of water in a short period of time.

The debris flow landform can usually be divided into three parts: formation area, circulation area and accumulation area, and the topography of the upstream formation area is mostly a scoop or funnel shape surrounded by mountains on three sides and an outlet on one side. The terrain is relatively open, with steep slopes, fragmented mountains and poor vegetation growth, which is conducive to the concentration of water and detrital materials. The topography of the middle reaches of the circulation area is mostly narrow and steep canyons, and the longitudinal slope of the valley bed allows the debris flow to fall rapidly.

The topography of the downstream accumulation area is usually an open and flat piedmont plain or river valley terrace, so that the accumulation has a place for accumulation.

Debris flows often occur in areas with complex geological structures, developed fault folds, strong neotectonic activities, and high intensity, and their surface rocks are broken and collapsed. The development of undesirable geological phenomena such as staggered falls and landslides provides abundant solid matter for the formation of debris flows**.

In addition, areas with loose rock structures, weak rock formations, easy weathering, jointed development, or soft and hard layering can also provide rich debris for debris flows** due to their vulnerability to damage. Human engineering activities such as soil erosion caused by deforestation, mining, and quarrying often provide large amounts of material for debris flows**. Water is not only an important part of debris flow, but also the excitation condition and transport medium (power**) of debris flow, the water source of debris flow exists in the form of heavy rain, water and snow melt and reservoir (pool) outburst water body, most of the water source of debris flow in China is heavy rain, long-term continuous rainfall, etc.

It is mainly related to topography, geological environment and hydrometeorological conditions.

At that time, hydrometeorological factors could directly provide hydrodynamic conditions.

The length of the valley is large, the catchment area is large, and the longitudinal slope is steep, which can provide conditions for the flow of debris flow.

The reasons for the formation of mudslides are as follows:

1. Topographic conditions

In terms of topography, it has high mountains and deep ravines, steep terrain, large longitudinal slopes of the gully bed, and the shape of the watershed is convenient for water flow. In terms of landform, the landform of debris flow can generally be divided into three parts: formation area, circulation area and accumulation area. Rock fragmentation and deep weathering in areas of collapse, landslide and rock pile community can easily become the source of recharge of solid matter in debris flow. The length of the valley is large, the catchment area is large, and the longitudinal slope is steep, which can provide conditions for the flow of debris flow.

2. Loose material conditions

Debris flows often occur in areas with complex geological structures, developed fault folds, strong neotectonic activities, and high intensity. The fragmentation of surface rock layers, the development of undesirable geological phenomena such as landslides, collapses, and staggered falls provide abundant solid materials for the formation of debris flows. Areas with loose, weak, weather-prone, jointed or hard-soft layers can also provide rich debris for debris flows due to their vulnerability to damage**.

How to escape in the event of a mudslide:

In the event of a mudslide, do not climb trees to escape, do not stay in deep depressions with heavy soil on steep slopes, do not hide behind rolling rocks or piles of rocks, and do not run up and down the valley. Mudslides are not like landslides. The trees were rolled up by the roots, and the earth and stones were wrapped and poured into the valley.

If there is heavy rainfall in the valley, do not panic when there is the sound of a mudslide and do not run in the direction of the mudslide. In the event of rain and mudslides, you must be decisive in determining a safe way to escape. If the path is perpendicular to the direction of the mudslide, climb the slopes on both sides.

The above content refers to Encyclopedia - Mudslides.

Weathering of rocks is pre-existing in its natural state.

1. In this weathering process, oxygen, carbon dioxide and other substances are based on the decomposition of rocks by free matter;

2. The decomposition of rocks caused by the absorption of acidic substances in the air in precipitation;

3. The decomposition of the rock layer under the soil by substances secreted by surface vegetation;

4. Loosening of the soil caused by frost freezing and dissolution of the soil.

All of these causes can lead to thickening of the soil layer and loosening of the soil layer.

Extended Trace Data:Other reasons: 1. Unreasonable excavation.

The excavation of railways, highways, canals and other engineering buildings is unreasonable. Some mudslides are formed by the construction of roads, canals, railways, and other construction activities that destroy the surface of hillsides.

2. Spoil and slag quarrying.

There are many examples of mudslides caused by this behavior.

3. Indiscriminate deforestation and reclamation.

Illegal logging and reclamation will cause vegetation to disappear, slope to lose protection, loose soil, ravines to grow, greatly aggravate soil erosion, and then destroy the stability of the slope, collapse, landslide and other adverse geological phenomena, resulting in debris flow. It's easy.

Answer]: The reasons for the frequent occurrence of debris flows in China are: the amount of precipitation and heavy rainfall; The earth's crust is active and the rocks are broken; Vegetation is severely damaged; Mountainous terrain; And so on.

A mudslide is a special torrent of landslides caused by heavy rain, heavy snowfall or other natural disasters in mountainous areas or other areas with deep ravines and steep terrain, and carries a large amount of sediment and stones. Heavy rains and floods occur periodically, so mudslides occur periodically.

Affected by the topography and landform, the mountain is high and the ditch is deep, the terrain is steep, the longitudinal drop of the gully bed is large, and the landform in the shape of the flowing city is easy to collect water, resulting in debris flow.

Affected by loose materials, areas with strong neotectonic activities and high intensity, surface rocks are broken, collapsed, scattered, and landslides are prone to debris flows.

Affected by precipitation, ice and snow melt, reservoir bursts, heavy rainfall, and long-term continuous rainfall can also lead to the occurrence of debris flows.

Mudslides in China mostly occur in summer. Volume.

The outbreak of debris flow in China is mainly triggered by continuous rainfall, heavy rainfall, especially heavy rainfall concentrated rainfall.

Therefore, the time rule of debris flow is consistent with the law of concentrated rainfall, with obvious seasonality, generally occurs in the rainy summer and autumn season, due to the difference in the time of concentrated rainfall is different, Sichuan, Yunnan and other southwest rainfall is mostly concentrated in June to September, therefore, the debris flow in southwest China mostly occurs in June to September, and the rainfall in northwest China is mostly concentrated in June, 7, 8 months, especially in July and 8 months, the rainfall is concentrated, and the intensity of heavy rain is large. Therefore, the debris flow in Northwest China mostly occurred in July and August two months, and according to incomplete statistics, the debris flow disasters that occurred in these two months accounted for more than 90% of all debris flow disasters in the region.