The mudflow in Sochi, Georgia, Taba and Lars

Being interested in the events in the country and the world, watching news feeds, we often see photos, video of natural disasters caused by mudflows. A catastrophe in the world is becoming more and more: whether global warming is to blame, or maybe human activity, or our planet itself passes through certain "catastrophic" periods of its history for some other reasons, but the consequences of cataclysms are always the same. Frightened people, refugees, lost homes and property, dead livestock, disfigured natural landscapes, only yesterday seemed like a fairy tale, and today resemble paintings from films on the theme of the apocalypse. So how does the village form, what can be done to avoid death and destruction, or to make the consequences of wildfire the least?

What is rural in nature?

The word has Arabic roots. In translation means "stormy stream". Muddy mud masses, rushing at great speed, sow death, sweep away everything on their way - buildings, natural landscapes along with all their inhabitants, from animals to humans. The mudflow contains many solid inclusions: large and small stones, rock particles, which, by the way, can be more than half of the total mass. Many settlements in the mountains exist for a long time, have a centuries-old history, happily avoiding natural disasters, but in nature there is something unusual, extraordinary (stormy and prolonged downpour, sharp warming, accompanied by a particularly rapid melting of snow, a glacier in the mountains) - and trouble is coming. The spree of the elements lasts usually not for long, a few hours, but this is more than enough to inflict irreparable damage to nature and people for several years, as, for example, after the mudflow in Georgia came down in 2013. Then, because of the disaster, the movement was completely paralyzed. Serious damage was also caused by the mudflow in Taba (we'll talk about it below).

Characteristics

The mudflow has a very high speed of movement. Mud soils often appear unexpectedly, not allowing enough operative measures to be taken to protect the population and nature. The mudflow, including hard rocks, rushes at a speed of 2-4 to 4-6 meters per second. As a result of the descent, the surrounding landscape can take quite a different outline: the stones literally erupt in a few hours new channels of rivers and streams, a layer of debris and mud covers the fertile foothill plains used for growing crops and grazing cattle. The flowering valley becomes dead and unfit for living and activity. The mudflow can descend in several stages, with each new wave even more increasing the size of the disaster.

What are the causes of this natural phenomenon?

1. Stormy and prolonged rainfall. If there were local "world floods", then they looked exactly like this, with descending descents, dying people and buildings.
2. Sharp warming, which is seasonal or off-season, which can cause melting snow and glaciers. The villages under the glacier are always at increased risk.
3. In areas with a large bias, a considerable part of the ground with debris can collapse into the river bed , and, thus, block the watercourse, send it along a different, unexpected path, provoke an avalanche.

What can serve as additional factors provoking a catastrophe?

The roots of the trees strongly strengthen the upper layers of the soil, preventing it from moving even under the influence of strong rainfall or weathering, therefore the thoughtless cutting of forest plantations is one of the main factors that increase the threat of such kind of spontaneous phenomena. Settlement for reasons of origin are divided into three groups: as a result of erosion, breakthrough and collapse.

Where are potentially dangerous foci?

Any part of a mountain river can become dangerous in the long term, where soil, rock, which is easily transported by water streams, accumulates. These can be cuts or potholes, as well as foci of dispersed mudflow.

Classification of foci

Rattle - the formation on the slopes, cutting rock, sod and other surfaces, they are small in length and depth and do not carry danger unless there is a flow that can lead to the movement of rocks. Vrez - formation, based on moraine deposits, associated with sharp differences in altitude. They are very ancient in origin. Young incisions may appear as a result of recent volcanic activity, as well as as a result of landslides and landslides. The cuts are larger than the ruts in depth and extent. A dispersed mudflow can occur on steep mountain areas, where many fragments of rocks and weathering products are concentrated. Such surfaces, significant in area, can appear as a result of a recent earthquake, an active tectonic process. The surface of these centers is dotted with furrows, in which gradually muddy products accumulate, which can, under certain conditions, merge into a single channel and bring down their power to objects located on a slope.

How to prevent avalanches?

Since one of the main reasons for the descent of water-mud flows is the loss of forest plantations, the problem can be tried to solve by planting trees. Hydraulic engineering structures (ditches, earthen ramparts, tracing), which divert potentially dangerous flows, can also give a considerable positive result. The installation of dams along the path of dangerous river beds and creeks will delay some of the mass that rides from the slope, which will somewhat weaken its destructive potential. Any other structures (excavations, basins, dams) will also reduce the risk of a disaster, it is important to strengthen the shorelines, to prevent their further erosion, especially if the banks are located buildings. From the passage of debris flows often suffer from road surface, for the protection of which it is advisable to construct trays (stone or reinforced concrete) above the road or under it in places of increased risk.

The most famous avalanches and their consequences, recorded by historical science

1. From August 17 to 18, 1891, in Tyrol, in the Austrian Alps, a large village came down: the wave reached a height of 18 meters, a vast area was covered with a thick layer of mud.
2. On March 1, 1938, Los Angeles suffered, resulting in the death of more than 200 people.
3. July 8, 1921, the stream fell on Alma-Ata (now Alma-Ata), several waves brought to the city of 3.5 million square meters. M of solid material.
4. In 1970, a catastrophe occurred in Peru, as a result of the mudflow activity, more than 60,000 people died, and 800,000 became refugees, lost property, and remained without a roof over their heads.

Disasters of our days

1. January 24, 2013 descended mudflow in Sochi. It was stopped as a result of timely and competently conducted work on the construction of fortifications by the city administration.
2. May 8, 2014 on the border of Egypt and Israel as a result of downpours was flooded several hotels. Then the mudflow descended in Taba, the roads were damaged. The consequences were eliminated within a week.
3. May 17, 2014 descended mudflow in Georgia, near the settlement of Gveleti. The stream blocked the Terek River. The section of the Vladikavkaz-Lars road was closed, an immediate threat of flooding several villages. The trouble was - water "found" a temporary channel, and its level did not exceed dangerous values. When the mudflow in Lars came down, the necessary measures were taken on time, the local population was immediately evacuated to a safe area.