Being interested in events in the country and the world, looking through news feeds, we often see photos, videos of natural disasters caused by mudflows. There are more and more catastrophes in the world: whether global warming is to blame, or maybe human activity, or our planet itself goes through certain "catastrophic" periods of its history for some other reason, but the consequences of cataclysms are always the same. Frightened people, refugees, lost homes and property, dead livestock, disfigured natural landscapes that only yesterday seemed like a fairy tale, and today they resemble pictures from films on the theme of the apocalypse. So how does mudflow form, what can be done to avoid death and destruction or to minimize the consequences of the rampant elements?
What is mudflow in nature?
The word has Arabic roots. It means "stormy stream". Muddy masses of mud, rushing with a hugespeed, sow death, sweep away everything in their path - 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 have existed for a long time, have a long history, happily avoiding natural disasters, but something unusual, extraordinary happens in nature (stormy and prolonged rainfall, sharp warming, associated with especially rapid melting of snow, glaciers in the mountains) - and trouble is looming. The rampage of the elements usually does not last long, a few hours, but this is more than enough to cause damage to nature and people that is irreparable for several years, as, for example, it was after the mudflow in Georgia came down in 2013. Then, because of the disaster, traffic was completely paralyzed. The mudflow in Taba also caused quite serious damage (we will talk about it a little later).
Features
Mudflow has a very high speed. Mud masses often appear unexpectedly, preventing the adoption of sufficiently prompt measures to protect the population and nature. Mudflow, including solid 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 on completely different outlines: stones literally break through new channels of rivers and streams in a matter of hours, a layer of debris and dirt covers the fertile foothill plains used forgrowing crops and grazing livestock. The blooming valley becomes dead and uninhabitable and unusable. Mudflow can descend in several stages, with each new wave further increasing the size of the disaster.
What are the causes of this natural phenomenon?
- Stormy and prolonged precipitation. If there were local "global floods", they looked exactly like this, with mudflows coming down from the mountains, people and buildings dying.
- Sudden warming, seasonal or out-of-season, which could cause snow and glaciers to melt. Villages below the glacier are always at risk.
- In areas with a large slope, a significant part of the soil with debris can collapse into the riverbed and, thus, block the watercourse, direct it in a different, unexpected path, provoke an avalanche.
What could be additional factors provoking a disaster?
Tree roots strengthen the upper layers of the soil well, preventing it from moving even when exposed to strong rain flows or weathering, therefore thoughtless cutting down of forest plantations is one of the main factors that increase the threat of natural phenomena of this kind. Mudflows are divided into three groups according to the causes of occurrence: as a result of erosion, breakthrough and landslide.
Where are potentially dangerous outbreaks located?
Dangerous, in the future, can be any section of a mountain river whereaccumulates soil easily moved by water flows, rocks. These can be cuts or potholes, as well as foci of dispersed mudflow formation.
Classification of outbreaks
Potholes - formations on the slopes, cutting rocky, soddy and other surfaces, they are small in length and depth and do not pose a danger until a flow appears that can lead to the movement of rocks. An incision is a formation based on moraine deposits associated with sharp elevation changes. They are very ancient in origin. Young cuts may appear as a result of recent volcanic activity, as well as as a result of collapses, landslides. The cuts are larger than the ruts in depth and length. Dispersed mudflow formation can occur on steep mountainous areas, where a lot of rock fragments, weathering products are concentrated. Such surfaces, large in area, may appear as a result of a recent earthquake, an active tectonic process. The surface of these centers is dotted with furrows, in which mudflow products gradually accumulate, which, under certain conditions, can merge into a single channel and bring down their power on objects located on the slope.
How to prevent avalanches?
Since one of the main reasons for the descent of water and mudflows is the loss of forest plantations, the problem can be tried to be solved by forest plantations. Hydraulic structures (ditches, earthen ramparts, tracing) that divert potentially dangerous flows can also provide considerablepositive result. The installation of dams on the path of dangerous riverbeds and streams will delay part of the mass rushing from the slope, which will somewhat weaken its destructive potential. Any other structures (pits, pools, dams) will also reduce the risk of a natural disaster, it is important to strengthen the coastlines and prevent their additional erosion, especially if buildings are located on the banks. The road surface often suffers from the passage of mudflows, for the protection of which it is advisable to build 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
- From August 17 to August 18, 1891, a large mudflow descended in Tyrol, in the Austrian Alps: the wave reached a height of 18 meters, a huge territory was covered with a thick layer of mudflow mass.
- Los Angeles was hit on March 1, 1938, killing over 200 people.
- July 8, 1921, the stream hit Alma-Ata (now Alma-Ata), several waves brought 3.5 million square meters to the city. m hard material.
- In 1970, a disaster occurred in Peru, as a result of mudflow activity, more than 60 thousand people died, and 800 thousand became refugees, lost property, were left without a roof over their heads.
Disasters of our days
- On January 24, 2013, a mudflow came down in Sochi. It was stopped as a result of timely and competently carried out work on the construction of fortifications by the city administration.
- May 8, 2014, on the border of Egypt and Israel, several hotels were flooded as a result of heavy rains. Then the mudflow came down in Taba, the roads were damaged. The consequences were eliminated within a week.
- On May 17, 2014, a mudflow descended in Georgia, near the Gveleti settlement. The stream blocked the Terek River. A section of the Vladikavkaz-Lars road was closed, and there was an immediate threat of flooding in several villages. The trouble has passed - the water "found" a temporary channel, and its level did not exceed dangerous values. When the mudflow came down in Lars, the necessary measures were taken in time, the local population was immediately evacuated to a safe area.
