Famous sat down. openings of culverts. channel strengthening, mudflow control and mudflow passage structures

Mudflows and landslides are the most dangerous forms of water erosion in the mountains. Mudflows (from Arabic flow) are powerful mud-stone flows that occur on mountain slopes after heavy rains.[...]

Mudflows in May 1998 in Tajikistan destroyed 130 schools and preschool institutions, 12 clinics and hospitals. 520 km of roads, 115 bridges, 60 km of power lines. Cotton crops on an area of ​​112 thousand hectares were damaged, orchards and vineyards were swept away by mudflows, and a significant number of livestock were killed.[...]

A stormy mudflow in July 1921, caused by massive melting of snow after a warm rainstorm, carried a stone block with a volume of 200 m3 over a distance of several kilometers near Almaty. The same flow completely buried the river flowing for about three kilometers with stones.[...]

Mamedov T.M., Mudflows and silvicultural measures to combat them. [...]

In order to combat mudflows, various dams are erected to delay solid runoff and pass a mixture of water and small fractions of rocks, a cascade of dams is arranged to destroy the mudflow and free it from solid material, retaining walls to strengthen slopes, upland runoff interception and drainage canals for drainage into nearby watercourses, etc.[...]

Powerful mudstone mudflows caused by a volcanic eruption in Colombia (1985), killed 23 thousand residents of Armero.[...]

A mudflow (in Arabic, “stormy stream”) is a temporary mud-stone stream that suddenly forms in the beds of mountain rivers. Such a mixture of water, mud, stones weighing up to 100 pounds, trees and other objects rushes at speeds of up to 15 km/h, sweeping away, flooding or carrying away bridges, buildings, destroying dams, dams, and collapsing villages. The volume of transported rock is millions of cubic meters. The duration of mudflows reaches 10 hours with a wave height of up to 15 m. Mudflows are formed due to prolonged rainfall, intensive melting of snow (glaciers), dam breaks, and improper blasting operations. According to their power, mudflows are divided into groups: powerful - with the removal of more than 100 thousand m3 of a mixture of rocks and materials (average frequency of repetition every 6... 10 years); medium power - with removal from 10 thousand to 100 thousand m3 of mixture (every 2...3 years); low power - with removal of less than 10 thousand m3 of mixture.[...]

Very powerful mud-stone mudflows, triggered by the eruption of the El Ruiz volcano in Colombia in 1985, caused the death of 23 thousand people in the city of Armero. Buildings and trees were cut down by the mudflow, like a huge bulldozer.[...]

In the USA (Utah) in 1930, mountain streams brought stone blocks weighing up to 200 g into some canyons (very deep gorges), destroyed houses located along the path of their movement, and caused valley residents several hundred thousand dollars in losses. It is amazing that mudflows of such destructive force occurred in relatively small catchment areas. But in these catchments, the forests were destroyed, and the soil was deprived of its typical macrostructure for forests, which allows it to quickly absorb precipitation. For the first time in the 20 thousand years that have elapsed since their formation, such exceptionally sized erosion products were carried out in a short instant into these valleys of Utah.[...]

The first include earthquakes, mudflows, tectonic faults, etc.; the second - landslides, flooding, subsidence, soil swelling, waterlogging, salinization, flooding, planar washout, erosion, aeolian processes. For each of these groups, rating coefficients are introduced, the combination of which evaluates the geodynamic vulnerability of the territory - from weak to high. The stability of the HS is assessed similarly.[...]

The normal operation of hydroelectric power plants is also threatened by mudflows in the mountains and siltation of reservoirs in the plains in the absence of woody vegetation due to irrational deforestation.[...]

In mountainous regions, often on small rivers or temporary streams with small catchment areas, short-term floods occur, carrying huge accumulations of sediment. These accumulations of solid material give the flow the character of mud, mudstone, or water-rock. These flows are called mudflows. Mudflows are formed as a result of intense rainfall, less often - intense snowmelt. A necessary condition for the formation of a mudflow is the abundance of accumulated weathering material in the catchment area and its rapid transport into the riverbed. Therefore, the lithological composition of rocks that make up mountainous areas, steep mountain slopes and significant slopes of streams are of great importance in the formation of mudflows. The lack of vegetation and bare slopes contribute to increased erosion and, consequently, the formation of mudflows. The movement of mudflows is of a pulsating, jam-like nature. Congestion occurs in certain sections of the riverbed. When a jam breaks, a mudflow sweeps down the river, saturated with sediment and having great destructive power. Congestion is repeated. Thus, a mudflow is a flow passing along a river in the form of successive shafts or waves. The duration of mudflows varies - from several minutes to several hours. During the passage of mudflows, intensive processes of channel erosion and sediment deposition occur. Mudflow is classified as a dangerous natural phenomenon. You can learn more about mudflows from the book “Mudflows” by S. M. Fleishman (Leningrad, Gidrometeoizdat, 1970).[...]

Specific, very rapid movements of material are mudflows and mudflows. They are confined to concave slopes and valleys of watercourses. Mudflow occurs as a result of oversaturation of sediments in the upper part of the valley with water as a result of heavy rainfall. A mushy mass of material flows down the slope. The material transported by a mudflow varies in size from fine fine earth to large blocks of rock. Mudflow cones are quite rich and fertile lands (Alma-Ata).[...]

Mudflow is a rapid mud or mud-stone (up to 75% of the total mass of the runoff) flow that suddenly appears as a result of rainfall or rapid melting of snow in the basins of small mountain rivers. The flow speed of a mudflow is usually 2.5-4.0 m/s, but sometimes when a blockage breaks through, it can reach 8-10 m/s or more. It develops in steeply sloped (at least 10°) valleys and depends on reserves of loose material. One of the reasons for the occurrence of mudflows is the destruction of forest vegetation on drainage surfaces.[...]

Natural pollutants can be dust storms, volcanic ash, mudflows, etc.[...]

Water erosion can be flat, streaky, gully, and also in the form of mudflows and landslides. [...]

There are mountains, the sea... MOTHER: The Caucasus is out of the question. War, mudflows, glaciers are melting and falling from the mountains... And without you, so many people are dying...[...]

One of the latest volcanic disasters is the eruption of the Arenas volcano (Colombia, 1985). Lava flows contributed to the formation of a powerful mudflow, which covered more than 3,000 hectares of farmland with a layer of many meters of mud. The city of Armero was destroyed and 17 settlements, about 22 thousand people died.[...]

The use of soils in mountainous areas is limited by the strong development of water erosion and especially mudflows. When developing and using soils, soil protection measures are very important: protection of forests, regulation of runoff by installing anti-mudflow structures, the use of a special soil cultivation system, terracing and afforestation of slopes, correct use pasture lands.[...]

To combat mudflows, it is useful to create powerful green protective strips in the directions of a possible mudflow.[...]

Soil erosion is extremely dangerous in the mountains, where destructive mudflows develop when slopes are exposed. The main reason for their formation is improper logging along the slopes, followed by skidding of logs, which strips off the vegetation cover, as well as excessive grazing of livestock and snow avalanches.[ ...]

Proluvium is formed in mountainous countries, at the foot of the mountains as a result of the activity of temporary water and mudflows of significant force. Proluvium is characterized by poor sorting and inclusion of coarse material.[...]

Natural environmental pollution is usually caused by catastrophic causes, such as volcanic eruptions, mudflows, etc., which occur without human influence on the environment. natural processes.[ ...]

Natural pollution occurs as a result of natural disasters: volcanic eruptions, earthquakes, mudflows, storms, hurricanes - without human intervention.[...]

In some mountain forests of the United States, 15 years of excessive livestock grazing was enough to cause such destructive mudflows that led to the decolonization of areas. [...]

Landscape-saving measures - work on engineering and bioengineering protection from soil erosion, coastal destruction, mudflows, snow avalanches, waterlogging, pollution of surface runoff and groundwater.[...]

The population of our planet and the natural environment are constantly threatened by such formidable natural disasters, such as landslides, landslides, mudflows. All of them belong to the category of gravitational and represent the displacement of earth masses down the slope under the influence of gravity. Landslides and other gravitational processes, especially if they are activated by technogenic factors, can cause catastrophic consequences and cause great damage to humans, biota and the entire natural environment.[...]

For example, international cooperation uses weather satellite data to predict hurricanes, typhoons, volcanic eruptions and mudflows. Earthquake prediction is possible based on systematic analysis chemical composition water in seismic areas, geodetic measurements of the inclination of the Earth's surface, measurements of elastic, electrical and magnetic characteristics of the soil, observations of changes in water levels in tared wells, and animal behavior. It is widely practiced to predict forest, peat and other landscape fires using a complex indicator based on the summation of coefficients that take into account temperature, geographic, climatological and other conditions. To search for hidden fires (peat, underground), special infrared photography from aircraft and artificial Earth satellites is used.[...]

As a result of prolonged rainfall, rapid melting of glaciers and snow, and the collapse of large amounts of loose debris into mountain river beds, mudflows (or mudflows) can occur. With a large mass and speed of movement (up to 20 km/h), mudflows destroy everything in their path. Particularly dangerous are mudflows that do not move along the channel, but go out onto adjacent structural paths, where various buildings are located and people may be present.[...]

Less catastrophic, at least more predictable than earthquakes, are natural disasters such as landslides, floods, mudflows, storms and hurricanes, fires.[...]

The selective felling system has a huge advantage over the clear-cutting system in that it better preserves the protective functions of the forest and prevents soil erosion and mudflows in the mountains, and mitigates floods on the plains.[...]

Violation of land use in the coastal zone leads to the development of coastal erosion. Erosion is especially severe in mountainous areas. As a result of the development of erosion processes, mudflows may occur.[...]

Water can bring more than just benefits. The harmful effects of water associated with floods, deformations of beds, banks, rivers and canals, destruction, washout or incorporation of fertile lands, water erosion of soil, as well as mudflows, cause considerable harm to the national economy.[...]

Based on the nature of occurrence, pollution is divided into natural and anthropogenic. Natural pollution arises as a result of natural, usually catastrophic, processes (for example, a powerful volcanic eruption, mudflow, etc.), without any human influence on these processes, anthropogenic - as a result economic activity person. The intensity of anthropogenic pollution is directly related to the growth of the world's population and, first of all, to the development of large industrial centers.[...]

To prevent and eliminate the consequences of the harmful effects of water: floods, inundations and underwatering, destruction of banks, dams, dams and other structures, waterlogging and salinization of land, soil erosion, gully formations, landslides, mudflows and other phenomena, measures are taken by federal authorities executive power, subjects of the Russian Federation and water users (Article 117).[...]

Based on the nature of their formation, pollution is divided into natural and anthropogenic. Natural pollution is caused by natural causes, without human intervention or as a result of its distant indirect influence. Often these are catastrophic processes - mudflows, powerful earthquakes, etc. This group also includes geochemical pollution, the primary source of which is the very emergence and development of our planet. It is expressed in a deficiency or excess of some element in any area. Deficiency, in turn, leads to various somatic disorders of human health. Local excess of an element in earth's crust contributes to the emergence of severe toxicosis, which often develops slowly, against the background of other disorders, and is therefore difficult to diagnose.[...]

The fundamentals provide for the responsibilities of enterprises, organizations and institutions to carry out measures to prevent or eliminate: floods, inundations and inundations; destruction of banks, protective dams and other structures; waterlogging and salinization of lands; soil erosion, formation of ravines, landslides, mudflows and other harmful phenomena.[...]

Emergency forecasting is a method of tentatively identifying and assessing the situation resulting from natural disasters, accidents and catastrophes. There are long-term and short-term forecasts. Long-term forecasts are aimed at studying and identifying seismic areas1, areas where mudflows or landslides are possible, the boundaries of areas of probable flooding during dam failures or natural floods, as well as the boundaries of damage centers during man-made accidents. Short-term forecasts are used to roughly determine when an emergency will occur.[...]

The flowers of oleaster and shepherdia are pollinated by insects, but in sea buckthorn they are most likely wind-pollinated. Unfortunately, the biology of pollination in suckers is almost unknown. As for the distribution of fruits, it is carried out by birds, and in the case of the oleaster also, possibly, by mammals. Sea buckthorn fruits are spread both by birds and sometimes by water (rivers, mudflows).[...]

It is prohibited to place landfills for the neutralization and burial of toxic industrial waste in wetlands, in green zones of cities, on lands occupied by forests or intended for afforestation, in sanitary protection zones of resorts, in the feeding zone of underground drinking water sources, in active karst zones, in areas of landslides, mudflows, avalanches, etc.[...]

The modern theory of environmental forecasting does not yet give a clear answer to the question of the possible interdependence and relationship between large-scale accidents and catastrophes and natural disasters manifested in the geosphere (earthquakes, volcanic eruptions; hurricanes, storms and tornadoes; thunderstorms, lightning, hail, drought; floods; mountain falls, screes, landslides and mudflows; snow drifts and avalanches; epidemics (Nb), epizootics (Pp), epiphytoties (P1), etc.). At the same time, individual observations and generalizations of available facts indicate a deep relationship between the consequences of global technogenesis and individual natural disasters and cataclysms occurring in nature.[...]

The importance of plantings in the fight against fires is primarily due to the fact that deciduous trees and shrubs contain a significant amount of moisture, so they burn slowly and, if a fire occurs, prevent (to some extent) the spread of fire. In addition, vegetation reduces the strength of the wind and thereby also reduces the possibility of fire spreading. The role of plantings is also great in the fight against mudflows. Sometimes the amount of impurities in the water and the flow speed are so great that the river turns into a kind of flow of mud and stones (the so-called mudflow), which can cause enormous destruction. So, in 1921. Almaatinka carried out 11.5 million m3 of mudflow in 5-6 hours. In some regions of the USSR, during the period of snow melting, mountain rivers carry in their waters a large amount of stones and crushed rocks. Such phenomena are observed in the area of ​​the Terek (Dzaudzhikau), Belaya (Maikop), and Vakhsha rivers.[...]

For landscape and morphological studies, you can use existing AKS. It should be borne in mind that in inhabited and quickly developed landscapes, construction and reclamation can change the PTC. In remote taiga areas it is possible to use relatively old ACS. Although here, too, the appearance of the landscape changes beyond recognition under the influence of fires, insect pests, natural disasters: windfalls, mudflows, etc. If aerospace surveying is carried out specifically and anew, it is necessary to determine and specify all its technical parameters and coordinate them with the nature of the landscapes being studied. [...]

Spontaneous P. I. and disasters cause environmental damage to nature, the natural environment - land, forests, waters, animals, and also cause damage to people's property, their health and life. Many P. i. almost unpredictable (thunderstorms, lightning, showers, storms, storms, whirlwinds), and therefore difficult to deal with. We can only talk about eliminating their consequences (restoration) and compensation. But some natural disasters can be predicted (mudflows, earthquakes, spills). In these cases, preventive measures and compensation payments to victims are possible.[...]

Emergencies that are natural in nature arise as a result of difficult-to-control spontaneous actions of natural forces; they are of varying probability in different geographical areas. By the nature of their action, individual natural phenomena may be similar to the effects of certain damaging factors Anthropogenic emergencies (for example, fires). CES of a natural nature, in addition to fires, also include earthquakes, floods, mudflows and landslides, avalanches, storms and hurricanes. Partially, natural emergencies can be prevented with the efficient work of meteorological services and a high level of technical equipment of society.[...]

The Water Code was determined by the state. water fund (Articles 36-37); objects of water relations (specific surface and underground water bodies - art. 7-22); isolated water bodies (Article 49); specially protected water bodies - water protection zones, water bodies (Articles 111 and 118); zones, districts and sanitary protection zones (Article 115); zones of environmental emergency and zones of ecological disaster on water bodies, the procedure for their declaration (Article 116); zones with harmful effects of water (natural disasters, mudflows - Article 117).[...]

Sources of anthropogenic pollution, the most dangerous for populations of any organisms, are industrial enterprises (chemical, metallurgical, pulp and paper, construction materials, etc.), heat and power engineering, transport, agricultural production and other technologies. Under the influence of urbanization, areas are most polluted major cities and industrial agglomerations. Natural pollutants can be dust storms, volcanic ash, mudflows, etc.[...]

A sustainable climax ecosystem includes not only biocenoses of the actual climax type. It always contains areas going through some stages of secondary succession, which begins in places of disturbances of a relatively small scale - the loss of old trees, local fires. In the discrete structure of the climax biocenosis, areas of secondary succession turn out to be habitats for a number of eurybiont species, which ensure the normal course of successional processes distributed in time and space of the ecosystem. We encounter primary successions in cases where a major disturbance of the state of the territory, for example, the loss of soil on deforested slopes of hills, powerful mudflows or other local disasters creates in place of an ecosystem a section of a “lunar landscape” devoid of life. It is first colonized by lichens and algae, with which the process of soil formation begins anew, then pioneer plants and small animals associated with them settle on this soil. The process of natural replacement of some species complexes by others begins, until after a few hundred years a climax-type ecosystem arises again.[...]

Gully forest strips are placed along the edge of the ravine and 30...50 m above its top. The width of ravine strips is taken to be from 20 to 50 m, depending on the ruggedness of the adjacent slopes with hollows and gullies and the general nature of the terrain, taking into account the direction and concentration of surface runoff . Anti-erosion landscaping of ravines should be designed in combination with simple hydraulic structures: embankment to divert surface runoff from eroded peaks, installation of drainage trays, dams, etc. To protect the slopes of dams and embankments on flooded floodplains from erosion, plantings of local shrubs and tree willows, placing them in strips along slopes within the highest and lowest water levels. Planting is carried out in the spring, starting from the line of the highest water level and continuing as it declines. To protect roads from erosion and destruction by mudflows, massive plantings are planted on mudflow-prone mountain slopes in combination with engineering strengthening measures.

Mudflow (mudflow) is a temporary rapid mountain flow of a mixture of water with a high content of stones, sand, clay and other particles (50-60% of the flow volume). Sel is something between a liquid and a solid mass. This phenomenon is short-term (usually it lasts 1-3 hours), characteristic of small watercourses up to 25-30 km long and with a catchment area of ​​up to 50-100 km2. Mudflow is a formidable force. The stream, consisting of a mixture of water, mud and stones, rapidly rushes down the river, uprooting trees, tearing down bridges, destroying dams, stripping the slopes of the valley, and destroying crops. Being close to a mudflow, you can feel the shaking of the earth under the impact of stones and blocks, the smell of sulfur dioxide from the friction of stones against each other, and hear a strong noise, similar to the roar of a rock crusher. The danger of mudflows is not only in their destructive power, but also in the suddenness of their appearance. After all, rainfall in the mountains often does not cover the foothills, and mudflows appear unexpectedly in inhabited areas. Due to the high speed of the current, the time from the moment a mudflow occurs in the mountains to the moment it reaches the foothills is sometimes calculated in 20-30 minutes. The entire area of ​​origin and impact of a mudflow is called a mudflow basin. The type of mudflow is determined by the composition of the mudflow-forming rocks. The main types of mudflows: water-stone (a mixture of water with predominantly large stones, y = 1.1-1.5 t/m3) mud (a mixture of water with fine earth with a small concentration of stones, volumetric weight y = 1.5-2 t/ m3) mud-stone (mixture of water, pebbles, gravel, small stones, y==2.1-2.5 t/m3) For a mudflow to occur, three mandatory conditions must simultaneously coincide: the presence on the slopes of the mudflow basin of a sufficient amount of easily transportable products of mountain destruction rocks (sand, gravel, pebbles, small stones); the presence of a significant volume of water to wash away stones and soil from the slopes and move them along the riverbed; sufficient steepness of the slopes (at least 10-15°) of the mudflow basin and water flow (mudflow bed). The direct impetus for the occurrence of a mudflow can be: intense and prolonged rainfall; rapid melting of snow and glaciers; earthquakes and volcanic activity, etc. Anthropogenic factors often lead to the occurrence of mudflows: deforestation carried out on slopes, blasting, quarrying, mass construction . How to prepare for a mudflow Usually, the places where mudflows can occur are known. Before going to the mountains, study these places along your route and avoid them, especially after heavy rains. Always remember that it is almost impossible for someone caught in a mudflow to escape. You can only escape from a mudflow by avoiding it. Before leaving home, during early evacuation, turn off electricity, gas and water supply. Close doors, windows and vents tightly. Early measures to prevent mudflows In mudflow-prone areas, anti-mudflow dams and dams are built to retain solid runoff and pass a mixture of water and fine rock fractions, a cascade of dams to destroy the mudflow and free it from solid material, retaining walls to strengthen slopes, upland runoff interception and drainage ditches for drainage of runoff into nearby watercourses, etc., are being constructed bypass channels, the level of mountain lakes is reduced, the soil on the slopes is strengthened by planting trees, observations are carried out, a warning system is organized and evacuation is planned. How to act in case of a mudflow Having heard the noise of an approaching mudflow, you should immediately rise from the bottom of the ravine up the drainage, at least 50-100 m. You must remember that stones of great weight can be thrown out of the roaring flow over long distances, threatening your life. Actions after a mudflow Provide assistance to the victims and assistance to the formations and authorities clearing debris and drifts along the path of the mudflow and in places where the bulk of the mudflow was carried out. If you are injured, try to provide yourself with first aid. If possible, the affected areas of your body should be kept in an elevated position, ice (wet cloth) and a pressure bandage should be applied to them. See your doctor. There are currently no methods for predicting mudflows. At the same time, for some mudflow areas, certain criteria have been established to assess the likelihood of mudflows occurring. Thus, for areas with a high probability of mudflows of storm origin, the critical amount of precipitation is determined for 1-3 days, mudflows of glacial origin (i.e., formed during outbursts of glacial lakes and intraglacial reservoirs) - the critical average air temperature for 10-15 days or a combination of these two criteria. Source of information: Wikipedia - mudflows; www.linkout.ru - natural disasters: Mudflows; ww.bti.secna.ru - life safety; www.booksite.ru - mudflows; bestreferat.ru - emergencies natural character; www.5ballov.ru - sat down - abstracts.

Sat down– these are channel flows that include a large amount of clastic material (at least 10–15% by volume), having a density 1.5–2 times greater than the density of water, moving in the form of a wave with a front height of up to 20–40 m and at a speed of up to 20–30 m/s (10–100 km/h) and exerting pressure on an obstacle with a force of up to tens of tons per square meter. The height of the front and the speed of movement of the mudflow, depending on the conditions of its occurrence, can take on different values. The mudflows got their name from the Arabic “sayl” - a stormy stream. Mudflows are typical for mountain valleys with a channel slope of 6–200; they usually last tens of minutes, less often 4–5 hours, can erode the riverbed to a depth of tens of meters, travel a path of kilometers long, less often - several tens of kilometers, form cones tens of meters wide, hundreds of meters long with a thickness of single deposits usually up to 5 , rarely up to 10 m. Mudflows form in all mountainous regions of the world, except Antarctica.

Mudflows are called rapid channel flows, consisting of a mixture of water and rock fragments, suddenly appearing in the basins of small mountain rivers. They are characterized by a sharp rise in level, wave motion, short duration of action (from 1 to 3 hours), and a significant erosion-accumulative destructive effect. A mudflow is a spontaneous (especially dangerous) hydrological phenomenon if the mudflow threatens populated areas, sports and health resort complexes, railways and roads, irrigation systems and other important economic facilities.

Potential mudflow source– a section of a mudflow channel or mudflow basin that has a significant amount of loose clastic soil or conditions for its accumulation, where under certain water conditions mudflows originate. Mudflow centers are divided into mudflow incisions, potholes and centers of dispersed mudflow formation.

Mudflow pothole called a linear morphological formation cutting through rocky, turfed or forested slopes composed of weathering crust of insignificant thickness. Mudflow potholes are characterized by their small length (rarely exceeding 500–600 m) and depth (rarely more than 10 m). The bottom angle of potholes is usually more than 15°.

Mudflow incision is a powerful morphological formation developed in the thickness of ancient moraine deposits and, most often, confined to sharp bends of the slope. In addition, mudflow incisions can form on accumulative, volcanic, landslide, and landslide terrain. They are significantly larger in size than mudflow potholes, and their longitudinal profiles are smoother than those of mudflow potholes. The maximum depths of mudflow incisions reach 100 m or more; the catchment areas of mudflow incisions can reach more than 60 km 2 . The volume of soil removed from a mudflow incision during one mudflow can reach 6 million m3.

Under the source of dispersed mudflow formation understand an area of ​​steep (35–55°) outcrops, heavily destroyed rocks, with a dense and branched network of grooves in which rock weathering products intensively accumulate and the formation of micro-debris flows occurs, which are then united in a single mudflow channel. They are usually confined to active tectonic faults, and their appearance is caused by large earthquakes. The area of ​​mudflow centers reaches 0.7 km 2 and rarely more.

The type of mudflow is determined by the composition of the mudflow-forming rocks. Mudflows are: water-stone, water-sand and water-silt; mud, mud-stone or stone-mud; water-snow-stone.

Water-rock mudflow– a flow in which coarse material predominates with predominantly large stones, including boulders and rock fragments (volumetric weight of the flow 1.1–1.5 t/m3). It is formed mainly in the zone of dense rocks.

Water-sand and water-silt mudflow– a stream in which sandy and silty material predominates. It occurs mainly in the zone of loess-like and sandy soils during intense rainfalls, washing away huge amounts of fine earth.

Mud mudflow is close in appearance to water-silt, is formed in areas where rocks of a predominantly clayey composition are distributed and is a mixture of water and fine earth with a low concentration of stone (volumetric weight of the flow 1.5–2.0 t/m3).

Mud-stone mudflow characterized by a significant content of clay and silty particles in the solid phase (pebbles, gravel, small stones), with their clear predominance over the stone component of the flow (volumetric weight of the flow 2.1–2.5 t/m3).

Rock-mud mudflow contains predominantly coarse material compared to the mud component.

Water-snow-rock mudflow– a transitional material between the mudflow itself, in which the transport medium is water, and a snow avalanche.

The formation of mudflows is caused by a combination of geological, climatic and geomorphological conditions: the presence of mudflow-forming soils, sources of intensive watering of these soils, as well as geological forms that contribute to the formation of fairly steep slopes and channels.

Sources of solid supply for mudflows can be: glacial moraines with or without loose filling; channel blockages and obstructions formed by previous mudflows; woody plant material. The sources of water supply for mudflows are: rains and downpours; glaciers and seasonal snow cover (during the melting period); waters of mountain lakes.

The most common mudflows are rain-fed mudflows. They are typical for mid-mountain and low-mountain mudflow basins that do not have glacial feeding. The main condition for the formation of such mudflows is the amount of precipitation that can cause the washout of rock destruction products and involve them in movement.

High-mountain basins with developed modern glaciers and glacial deposits (moraines) are characterized by glacial mudflows. The main source of their solid nutrition is moraines, which are involved in the process of mudflow formation during intensive melting of glaciers, as well as during the outburst of glacial or moraine lakes. The formation of glacial mudflows depends on the ambient temperature.

The immediate causes of mudflows are rainfall, intensive melting of snow and ice, outburst of reservoirs, and, less commonly, earthquakes and volcanic eruptions. Despite the variety of reasons, the mechanisms of mudflow initiation can be reduced to three main types: erosion, breakthrough and landslide (Table 2.16). Thus, during the formation and development of mudflows, three stages of formation can be traced:

more or less long-term preparation on the slopes and in the beds of mountain basins of material that serves as a source for the formation of mudflows (as a result of weathering of rocks and mountain erosion);

rapid movement of rocky, out-of-balance material from elevated areas of mountain catchment areas to lower areas along mountain beds in the form of mudflows;

accumulation of mudflows in low areas of mountain valleys in the form of channel cones or other forms of mudflow deposits.

Mudflows form in mudflow catchments, the most common form of which in plan is pear-shaped with a drainage funnel and a fan of hollow and valley channels that pass into the main channel. The mudflow catchment consists of three zones in which mudflow processes form and occur: mudflow zone, where water and solid material are fed; transit zone(mudflow movement); unloading area(massive deposition of debris flows).

Mudflows (from Arabic sayl - stormy stream * a. mudflows, earth flows, sills; n. Schlammstrome, Murgange, Muren; f. eсoulement de boue; i. сorrientes de barro) - sudden flows with a high content of solid material that occur in in mountainous areas where there are large reserves of loose debris material, during rains, during intensive melting of snow and ice, as well as during the breakthrough of dammed lakes. Technogenic activities also play an important role in the development of mudflows: deforestation, excessive grazing of livestock, creation of dumps during mining operations. Based on the primary nature of the movement of loose clastic material, erosional and landslide mudflows are distinguished. With the erosive nature of the origin of mudflows, the disruption of bonds with particles (particle release), displacement and transport are carried out by water or suspension, the solid phase moves both in a suspended and in a transported state. In landslide mudflows, the initial displacement of the solid phase (loose clastic material) occurs along one surface in the form of a slip or landslide-flow, without disturbance or with slight disturbance of the structure. As the displaced massif moves further and water enters, the structure is disrupted and the slide or landslide-flow turns into a mudflow.

According to the granulometric composition of the loose clastic material, mudflows are divided into mud (particles of 2 mm in size less than 10%), grus (pebbles and boulders less than 10%), pebble (pebbles and boulders more than 10%, but boulders less than 10%), boulder (boulders and boulders more than 10%). The coarse part (particles larger than 2 mm in size), as a rule, plays the role of an inert material, fine earth (up to 2 mm) forms a cohesive soil (mudflow) mass, holding particles on the surface with a significant amount of water.

Based on physical types, a distinction is made between cohesive mudflows, in which all the water (or most of it) is in a bound state with clay particles, and non-cohesive mudflows, the transporting mass of which is mainly free water. Mudflows, as a rule, do not move continuously, but in separate shafts (height 3-10 m), which is caused by the formation of jams and their subsequent breakthrough in narrowing channels (due to the accumulation of solid material). Debris flows can flow in turbulent and laminar modes, with a movement speed of up to 10-15 m/s. The duration of mudflow passage is usually 1-3 hours, sometimes 12 hours or more. The density of the flows depends on the content and petrographic composition of the solid component and changes as the mudflow moves and with depth. With high turbulence, the mudflow mass contains a large amount of air, especially in the upper part of the flow. The density of non-connected mudflows is from 1.1 to 1.5 t/m 3, connected - from 1.4 to 2.0 t/m 3 (rarely more). The maximum flow rates of mudflows are mainly thousands of m 3 /s (sometimes up to several million m 3 /s), the volume of total removal of solid material is tens of millions of m 3, the size of the transported debris is 3-4 m (in diameter), the mass is 100- 200 t.

Mudflows occur in mountainous areas of all climate zones - from the tropics to the polar regions. In CCCP they are most intensely manifested in Central Asia, in the Caucasus, in the Carpathians, Crimea, as well as in Kamchatka, Sakhalin, Siberia, the Urals, Transbaikalia, Khibiny and other areas. Catastrophic mudflows were observed on the Malaya Almatinka River, tributaries of the Terek River and other rivers. For example, mudflows that formed during a heavy rainfall in the basin of the Malaya Almatinka River in 1921 carried more than 3 million m 3 of mud-stone mass into the city of Alma-Ata, the total volume of this mass with water was more than 10 million m 3, the maximum flow rate was over 5000 m 3 /s.

In connection with the catastrophic consequences caused by mudflows, methods for forecasting mudflows and complexes of anti-mudflow measures are being developed to prevent the occurrence of mudflows and protect economic facilities from their effects. These measures include consolidation of the soil cover, planting of plantations, preventive lowering of mountain reservoirs threatening to burst, clearing accumulations of loose debris material, etc. To protect against mudflows, continuous and through dams and structures are created that ensure the passage of mudflows (mudflow chutes, bridges, chutes, etc.) , deep nanosoul traps are used. A unique set of anti-mudflow measures was carried out in the Almaty region. It includes a rock-fill earth dam 150 m high on the Malaya Almatinka River, created using directed explosions, a solid concrete dam on the Bolshaya Almatinka River (height 40 m), a number of through dams, stabilization of tributary channels with a system of dams and through structures made of reinforced concrete, systematic descent of moraine lakes. Sometimes mudflows are caused artificially, for example, for digging exploratory trenches, by discharging previously accumulated water through a pre-prepared ditch.

Mudflows consist of large masses of destroyed rocks in a loose state, which accumulate over years at the bottom of gorges and steep slopes. During intense rainfalls or during the outburst of glacial lakes located above, mud-stone mudflows are formed and flow down, destroying everything in its path.
In mountainous areas, heavy rainfall or rapid snowmelt causes the formation of temporary torrential streams. A powerful stream flowing down steep slopes has enormous force and, like mountain rivers, carries along small rock fragments, large blocks and boulders. Acting like a battering ram with captured debris, such a stream destroys the ledges and unevenness of mountains encountered along the way, carries them along with it and becomes more and more saturated with stone material.

Next, the flow captures the upper layers of fine-clastic material and soils and gradually turns from water into mud-stone. Such a flow is called mudflow or silt. Temporary mud-stone flows are widespread in the Caucasus and Central Asia. The content of transported material in debris flows is very high and sometimes exceeds the water content. Breaking out of a mountain gorge onto the plain, the mudflow quickly loses speed and spreads across a relatively large area in the form of a cone. Water from a mudrock flow filters to its base, and the transported rock material settles to form a fan or dry delta.

Mudflows are a mixture of soil, stones and water with a fairly high density of 1.2-1.9 t/m³, which flows down the beds of various mountain rivers and dry valleys after rainstorms at a speed of up to 6 m/s. When leaving the ravine, in places where the slope decreases, the velocity of the mudflow also decreases and an alluvial cone is formed.

The detrital mass brought by such a flow consists of almost unrounded fragments and is completely unsorted: among large blocks and boulders there are gravel-sand-clay particles. Deposits of debris flow cones are called proluvial or proluvium. Debris flows pose a great danger to populated areas located in their zone of action. The famous mudflow of 1921, which burst out of a mountain gorge near the city of Alma-Ata, demolished all the buildings located at the foot of the mountain. Then he burst into the city, turning the streets into raging mud-stone rivers.

Houses were torn off their foundations and carried away along with people. A mass of stone material about 1.5 million tons.

Picture 1. Destruction of populated areas caused by mud-stone flows

Mudflows arise suddenly and last a relatively short time, lasting a few hours, but are capable of forming significant volumes of mud-stone materials that are washed away in one mudflow. A mudflow is capable of washing away and carrying stones with a diameter of up to 1.5 meters. Considering the high speed of the mudflow and the volume of transferred stones, the protection of cities and villages, as well as various structures located in the action area, is a big problem.

To solve such problems, it is necessary to erect expensive and complex structures such as retaining walls or dams. Depending on how much water the mud-stone flows contain, the mudflow can move as a homogeneous viscous mass or as a turbulent flow of water, stones and mud. The stream carries along a huge number of stones various diameters and washes away huge volumes of soil from the surface. In a mudflow, small stones move in suspension, while larger ones move by rolling along the bottom of the thalweg.

Methods for protecting buildings from mudflows

Mountain rivers and mudflows are capable of carrying stones of enormous size and in large quantities, which can pose a threat not only to various structures and communications such as bridges, roads, but also to nearby cities. If construction is inevitable in the area where mudflows form, various measures are taken to protect structures from mudflows.

For example, bridges are built with spans that do not restrict the flow of mudflows, and single-column supports are used. The openings of bridges are significantly increased, since it is difficult to predict the volume of mudflows, which vary depending on the amount of precipitation. The openings of small bridges quickly become clogged with sediment and in this case the mudflow flows over the bridge and embankment.

In order to protect cities and large structures of great importance, sediment-retention dams are installed on the upper side of mountain slopes. Such dams slow down the speed of the mudflow and cause sediment deposition. There are two types of dams: continuous and intermittent. Continuous dams are built when the width of the river bed exceeds 100 meters.

In this case, the required length of the dam depends on the width of the channel and also on the size of the particles that mudflows deposit. The length of the dam in this case is determined by the formula:

L=b*B, where b is the coefficient of restriction of the channel by the dam, B is the width of the channel.

Dams of intermittent type are built when the width of the channel is up to one hundred meters. In this case, the length of the dam is determined by the formula and the opening of the dam is determined depending on the passage of the required amount of mudflows with a given frequency. In the transverse profile, such dams are built with a trapezoidal cross-section. The width of the dam at the top ranges from 0.5 to 2.0 meters, depending on the size of the transferred stones and the intensity of the mudflow.

Figure-2. Construction of partition walls to combat mudflows

A measure to combat mudflows is, first of all, the restoration of vegetation cover with a powerful root system, as well as the installation of partition walls (Figure 2). The construction of terraces can be used as an anti-mudflow measure (Figure 3).

Figure-3. Terracing scheme to combat mudflows

Along the terraced slope, the mudflow will flow from step to step, ending up in the ditches prepared for it. Recently, dams constructed using the directed explosion method have been used to combat mudflows. For example, such a dam was created in 1966 in the Medeo tract in the mountains near Alma-Ata. With the help of an explosion, almost 2 million tons were placed into the dam rock. Along with mudflows, there are channelless flows from slopes. A complex of loose formations that accumulate at the foot of mountains as a result of temporary mountain flows washing away the clastic material that appears during the weathering of the bedrock composing these mountains is called proluvium.

Table 1. Comparison of properties of water-continental deposits

Proluvium is characterized by poorly sorted and weakly rounded fragments. It forms alluvial cones that can merge into one strip bordering the base of the horizon. The difference is in power, duration of action and direction water flows determines the difference in the properties of the rocks they deposit.

This difference is most clearly visible from the comparison shown in Table 1. From Table 1 it is clear that with a fairly close mineralogical and granulometric composition Various types deposits of flowing surface water have different properties. This should be taken into account when designing and constructing structures.

Classification of mudflows

The study of the formation and action of mudflows made it possible to classify them according to a number of characteristics. According to the research of E.K. Rabkova, it is possible to distinguish between cohesive or structural mudflows, turbulent-flowing water-stone and turbulent-flowing mud-stone. Structural or cohesive mudflows form in mountainous areas. IN geological structure The presence of clay rocks and clays is mandatory in the drainage basin. In addition, there are rocks that can produce screes and difficult-to-crush fragments: limestones, shales, crystalline rocks.

The volumetric mass of the flow is very high and amounts to 1.9-1.6 t/m³. Clay fractions make up no more than 25-30% of the solid part of the flow. The rest consists of sand, crushed stone, gravel and boulders. Water is included in the mudflow mass as one of the components. To maintain the movement of the flow, a straight direction is necessary, without bends. Such a flow moves as one structural whole and, when stopped, freezes without breaking up into its component parts. Structural flows destroy all structures and other obstacles encountered along the entire width of the movement. With slopes of 0.05-0.06 degrees on the alluvial cone, the bottom of the channel is covered with a layer of frozen mudflow.

Turbulent-flowing water-stone mudflows also form in mountainous zones. The drainage area of ​​such flows is composed of intrusive rocks, as well as limestones, sandstones and well-cemented conglomerates. The presence of coarse material: gravel, pebbles, coarse sand is also possible. The presence of clayey rocks is not significant. The volumetric mass of the mudflow in such streams it is 1.6-1.3 t/m3. The stream is poorly saturated with fine earth. Individual boulders and boulders reach 1-2 m in circumference. The nature of the movement of individual flow waves is pulsating and jammed. The presence of large fragments and the jammed nature of the movement determines a large destructive force. Some sorting of the carried out material is possible on the alluvial cone.

Turbulent-flowing mud-stone mudflows are formed in both mountain and foothill zones. The drainage area is characterized by a predominance of fine-clastic and clastic material, sandy loam and loam. There is a large amount of crushed stone and pebbles. The volumetric mass of the mudflow is relatively small and amounts to 1.4-1.05 tons /m³. The flow is saturated with suspended fine fractions and pebbles drawn along the bottom.

The deposition of large masses on the alluvial cone leads to the flow overflowing the barriers, accompanied by the destruction of roads, bridges and other structures. Unlike structural flows, destruction occurs not by impact, but by erosion. The nature of the flow movement is congestion-free. At the removal cone, some sorting of the transported material by size occurs.

Table 2. Main types of mudflows and possible reasons emergence

Main types of mudflows and possible causes

Classification of mudflows according to the granulometric composition of the solid component:

1. Water-stone - is a mixture of dirty water with large stones (rock fragments, boulders, etc.) with a volumetric weight of 1.1–1.5 t/m³. The water-rock flow is formed mainly in the zone of dense rocks.

2. Mud - is a mixture of dirty water with particles of clay and silty soil in the solid phase with a slight concentration of stones. Volumetric weight ranges from 1.5-2.0 t/m³.

3. Mud-stone flow is a mixture of water with fine earth particles and mostly small stones. The volumetric weight of such a flow is 2.1–2.5 t/m³.

4.Water-snow-rock consists mainly of water, snow avalanches and stones of different sizes. Such a mudflow is very heavy and the mudflow reaches up to 5–12 t/m².

Classification of mudflows by genesis:

1. Alpine type - this type is characterized by seasonal rapid melting of snow (Canada, USA, Andes, Himalayas, Alps)

2. Desert type - found mainly in semi-arid or arid areas that experience sudden heavy rainfall. Most often observed in areas such as Arizona, Nevada, California.

3. Lahars are mud flows of volcanic origin that appear on the slopes of volcanoes after heavy torrential rains.

The following mudflows are distinguished based on their frequency:

a) high activity (repeated within 3-5 years and maybe more often)

b) average activity (repeated within 6-15 years)

c) low mudflow activity (repeated once every 16 years).

By impact on structures:

1. Low-power - they create small erosions at the base and clog the culverts of structures.

2. Medium-power - they create strong erosion at the base of bridges and culverts, completely clog the openings of culverts. They can also demolish foundationless structures.

3. Powerful and has great destructive power. It can demolish bridge trusses, supports of bridges and overpasses, and also destroy roads.

4. Catastrophic - completely destroys buildings and sections of roads.

By water source:

1. Rain - such mudflows are typical for low-mountain and mid-mountain mudflow basins that do not have glacial feeding. The conditions for the formation of these mudflows are heavy rainfall, washing away destroyed rocks from the slopes.

2. Glacial - they are characterized by low-mountain and mid-mountain mudflow basins that do not have glacial feeding. They are formed due to heavy precipitation that can wash away the products of rock destruction.

3. Volcanogenic - formed mainly during earthquakes. Sometimes in some cases they are formed during a volcanic eruption.

4. Associated mudflows - can consist of water, sandy and clayey soil particles. The mudflow moves as one whole and does not follow the bends of the river bed, but flows over the banks. In some cases, it can destroy and straighten river beds.

5. Unconnected flows are able to move with high speed in this case, constant rolling of stones and abrasion occurs due to frequent collisions. The flow usually follows the river bed, destroying it in places and repeating its bends.

By volume of transferred solid mass:

According to the main factors of occurrence

1. Zonal manifestation. They are formed due to heavy precipitation and are of a zonal nature. As a rule, mudflows occur systematically along the same paths.

2. Regional manifestation. They are formed due to geological processes. As a rule, the paths of movement of mudflows are not constant and the flow is episodic.

3. Anthropogenic. Occur as a result of human economic activity.