What terrain is prone to mud and wet flows, and what terrain is debris flows most likely to occur

Debris flow is a torrent formed by saturation and dilution of soft soil mountains containing sand and gravel by heavy rain and floods, and its area, volume and flow are large, while landslides are small areas of diluted soil mountains. A typical mudslide consists of a viscous slurry suspended with coarse solid debris and rich in silt and clay. Under appropriate topographic conditions, a large amount of water is soaked into the solid accumulation material in the slope or ditch bed, which reduces its stability, and the solid accumulation material full of water moves under the action of its own gravity, forming a debris flow.

Mudslides are a catastrophic geological phenomenon. Mudslides erupt suddenly and violently, and can carry huge boulders. Because of its high speed and powerful energy, it is extremely destructive.

Three basic conditions are required for the formation of debris flows: there is a suitable terrain with steepness to facilitate the collection of water and sediment; Abundant loose solids accumulate upstream; There is a sudden large amount of turnover in a short period of time**. Debris flow formation Topographic and geomorphological conditions In the terrain, it has high mountains and deep ravines, steep terrain, large longitudinal drop of gully beds, and the shape of the flow city is convenient for water flow collection.

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 of the outlet 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. Debris flow often occurs in areas with complex geological structures, developed fault folds, strong neotectonic activity, and high intensity.

The development of undesirable geological phenomena such as surface rock fragmentation, collapse, staggering, and landslides provide abundant solid materials for the formation of debris flows. In addition, areas with loose rock structure, weak rock formation, easy weathering, jointed development, or soft and hard layering can also provide abundant debris for debris flows due to their vulnerability to damage**; Some human engineering activities, such as soil erosion caused by deforestation, mining, quarrying, etc., often provide large amounts of material for debris flows**. Water source conditions Water is not only an important part of debris flow, but also the excitation condition and transportation medium (power) of debris flow, the water source of debris flow, there are heavy rain, water and snow melt and reservoir outburst water and other forms. The main sources of debris flow in China are heavy rain and long-term continuous rainfall.

Remember.

The terrain is high, there are not many tall vegetation in the bald mountains, and the soil structure is mostly sandy and rocky.

The terrain is low, there is enough water, and there are few trees on the ground.

Mountains and valleys are prone to mudslides.

——— ridge ———

Because, it has high mountains. Low on both sides. Sloping downward.

Suggestion. Geography is mostly observed from various aspects.

Latitude. What latitude it is at determines its climate. If it is an arid area, there is little rain. There is no need to talk about mudslides.

Mountain vegetation, if it is a lot of shrubs. It will conserve water.

Which side of the mountain. The mountain has a windward slope and a leeward slope. The windward slope is watery and prone to debris flows.

Leeward slope anti-sub.

The valley is the catchment line. First of all, it is necessary to make clear that the main driving force of debris flow is water flow, usually the rainfall in the mountainous area is too heavy and too strong, the stronger the erosion of the surface soil of the mountain, the mud and water and stones are mixed together, and the debris flow is formed, and the large-scale debris flow has considerable destructive power. It is the nature of water to flow down the catchment line, and the mudslides it pushes naturally gushed out of the valley.

If this is a multiple-choice question, it should be a ridge, a valley is not sufficient, and a cliff should be called a collapse rather than a mudslide. The high terrain of the ridge and the low terrain around it are necessary for mudslides to form.

It's a natural disaster, it's caused by torrential rains, it's mud that comes down from the mountains, it's like a waterfall, and it's scary.

The Jingjiang section is a key flood control area in the Yangtze River Basin, where the river channel is curved, the flood carrying capacity is poor, the peak flood flow is large, the duration is long, and the embankment flood control standard is very low.

Why are floods so frequent in the Jingjiang River? To illustrate this problem, we should first understand the flood characteristics of the Jingjiang River. The flood characteristics of the Jingjiang River are as follows:

First, the flood season is long. The flooding of the Jingjiang River is mainly caused by rainfall, but it is also affected by the four waters of Dongting Lake. The rainfall bearing area of the upper reaches of the main stream is about 1.03 million square kilometers, and the rainfall is abundant.

Under normal circumstances, the rainy season of Dongting Sishui is earlier than that of the upper reaches of the Yangtze River, so the flood control time in a normal year starts from May to September, which lasts for up to 5 months. The second is the high volume of the flood peak and the duration of the calendar. According to the survey and hydrological records of the Jingjiang River section, in the more than 800 years from 1153 to the present, the flow of Yichang was greater than 80,000 cubic meters per second 8 times, of which more than 90,000 cubic meters per second was 5 times, and the largest was the peak flow of 105,000 cubic meters in Yichang in 1870 (the peak flow of Zhicheng flood was 110,000 cubic meters per second).

In the more than 100 years since 1877, there have been 24 times when the peak flood flow in Yichang exceeded 60,000 cubic meters per second. The flood volume of the above eight major floods was more than 20 billion cubic meters in three days and more than 40 billion cubic meters in seven days. Third, the composition of floods is complex and often encountered.

When there is a large flood in the upper reaches of the Jingjiang River and a small flood volume in the four waters of Dongting Lake, the focus of flood control in the Jingjiang River is above the Shishou River section. On the contrary, the focus of flood control is below the Shishou River section, especially the upper and lower sections of the Chenglingji River. If the Jingjiang River and Dongting Lake are flooded, the entire Jingjiang River section will be in a state of emergency, especially in the West Dongting area and Jingjiang Zhoutan Minyuan. Knowing the characteristics of Jingjiang floods, let's talk about the reasons for the frequent floods in Jingjiang:

First, the flood volume in the upper reaches of the Yangtze River is greater than the safe discharge in the Jingjiang section. The Jingjiang section consists of four diversions, and the flow rate that can only be safely passed is about 68,000 cubic meters per second. If the amount of water coming from the upstream exceeds the safe discharge of the Jingjiang River, the excess flood will find a way out, or it will be actively diverted or allowed to burst, and one of the two will be the root cause of frequent floods in the Jingjiang River.

Second, the long-term siltation of sediment and the impact of human reclamation and development activities have led to the decreasing area and volume of Dongting Lake to store floodwaters, and the function of regulating and storing the Yangtze River and Hunan's four rivers of Hunan, Zizi, Yuan, and Li has decreased, forcing the water level of the rivers and lakes to continue to rise. Third, the diversion flow from the four mouths of Jingnan to Dongting Lake decreases, and the flow of the main stream of the Jingjiang River will inevitably increase. Fourth, despite years of efforts, the flood control standard of the Jingjiang embankment is still low, only about once in 10 years, and only once in about 20 years in the application of the Jingjiang flood diversion project.

This is the lowest defense standard among the seven major rivers in the country. According to the current situation of such embankments, if the volume of Zhicheng reaches 70,000 cubic meters per second, and the water level of Chenglingji exceeds one meter at this time, the flood control of the Jingjiang River will be in a severe situation of all-round tension.

The middle and upper reaches of the region have high terrain, rapid water flow, more sediment, less drainage, and often flooding.

Generally, rivers have a high flow velocity in the upper reaches of the river, because the rivers mostly originate in mountainous areas and have large slopes in mountainous areas. There are also special ones, such as the Congo River, which flows quickly downstream.

Most of the flood disasters in the lower reaches are due to the fact that the downstream is mostly plain, the terrain is flat, the flow rate is slow, the sediment is easy to deposit, the river bed becomes high, and the river overflows. In addition, due to the inflow of the middle and upper tributaries, the amount of water downstream tends to be large. It is prone to flooding.

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Starring: Deng Fei.

Director: Kan Ruohan.

Genre: Comedy, sci-fi, disaster drama.

Duration: 94 minutes.

Year: 2017

Region: Mainland Profile.

Causes of frequent hydrological disasters in the Yangtze River BasinThe Yangtze River Basin is a frequent area of hydrological disasters such as heavy rainfall, floods, and storm surges, and its causes are the result of the combined action of various factors.

1) Influence of the southwest monsoon and southeast monsoon. The Yangtze River flows through humid areas, with wide basins and many tributaries, and is affected by the double monsoon, with a lot of precipitation and concentration, in May, the rain belt is located on the south bank of the Yangtze River, and in June it is located on the main stream and the north bank. In summer, there are many heavy rains, and the main and tributaries have a long flood season and a large amount of water.

In abnormal years, the rain belt hovered on the north and south banks of the Yangtze River, causing floods on the south bank, the Sichuan River, and the Han River at the same time, and the main stream experienced a major flood.

2) The junction of the stairs is mountainous and windwardly. It is located on the windward slope and has many terrain and rain. The basin is mountainous, with large drops and rapid currents.

3) The middle and lower reaches are low-lying and flat, and the drainage is not smooth. The middle reaches of the area are low-lying and flat, with slow water flow, sediment accumulation and poor drainage.