What are the conditions for the development of debris flows? What are the conditions under which deb

Debris flow is a special torrent in a mountainous valley that is triggered by water sources such as heavy rainfall and water and snow meltwater, and contains a large amount of sediment and stones.

The basic conditions for the formation of debris flows.

The formation of debris flow must meet the following three conditions at the same time: steep terrain and landform that are convenient for water collection and collection; There is an abundance of loose substances; There is a large amount of water in a short period of time.

1) Topography and geomorphological conditions: the terrain has high mountains and deep ravines, steep terrain, large longitudinal drop of gully beds, and the shape of the flowing city 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.

The topography of the upstream formation area is mostly surrounded by mountains on three sides, and one side is scoop-shaped or funnel-shaped, and the terrain is relatively open, the surrounding mountains are high and steep, the mountains are broken, and the vegetation growth is poor, 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 is large, so that the debris flow can be rapid and straight. The topography of the downstream accumulation area is an open and flat piedmont plain or river valley terrace, so that the accumulation has a place for accumulation.

2) Loose material conditions: Debris flows often occur in areas with complex geological structures, developed faults and folds, strong neotectonic activities, and high intensity. Surface rocks are broken, and undesirable geological phenomena such as collapses, staggered falls, and landslides develop.

Provides abundant solids for the formation of debris flows**; In addition, areas with loose rock structure, weak rock formation, easy weathering, jointed development, or soft and hard alternating layers, due to their vulnerability to damage, can also provide rich debris for debris flows**; Some human engineering activities, such as soil erosion caused by deforestation, mining, quarrying, etc., often provide large amounts of material for debris flows**.

3) Water source conditions: water is not only an important part of debris flow, but also the excitation condition and transport medium (power) of debris flow.

There are stones, there is earth, and there is water.

Debris flows are formed under the following conditions: steep terrain, abundant loose deposits, sudden, sustained heavy rainstorms or the outflow of large amounts of ice meltwater.

In the terrain, it has high mountains and deep ravines, steep terrain, large longitudinal drop of ditch bed, and the shape of the flowing city is convenient for water flow collection and burning. Debris flows often occur in areas with complex geological structures, developed fault folds, strong neotectonic activities, and high intensity. The fragmentation of surface rocks, the development of undesirable geological phenomena such as collapses, staggered falls, and landslides provide abundant solid materials for the formation of debris flows.

The water sources of debris flows are in the form of heavy rainfall, ice and snow melt, and water bodies bursting from reservoirs. The main sources of water for debris flows in China are heavy rainfall and long-term continuous rainfall.