Due to lack of land people started building their houses on the slopes and they even started construction on old landslides. The HC underlies the entire hill country. Further more these two units lay completely in the dry zone of island and rainfall intensity are never high enough to cause landsides. With the expansion of the population this peasantry sub-divided their limited lands to meet the need of the growing families until landlessness and poverty became their way of life. A summary of landslide triggering conditions is given below. For the period of loss of life damage to property caused by landslides is not so severe as compared to the period between 19This trend reveals acceleration on landslide hazards in Sri Lanka in the coming years.
Essay on Landslides: Definition, Action Steps and Control
What should you do if you think a landslide is about to happen:. By maintaining these channels and drains we can reduce the landslides. Decks and verandas tilting or moving away from the main house. Approximately 40 houses have been completely or partially destroyed in Kandy and surrounding area owing to inclement weather conditions and landslides. . In the past, when the landslides occurred on the higher slopes they were hardly noticed because there was no inhabitance on the higher slopes. The maps will now help sort out the danger zones so that they could be cleared of all human habitation. Separation occurs along discontinuities such as fractures, joints, and bedding planes, and movement occurs by free-fall, bouncing, and rolling. The two major types of slides are rotational slides and translational slides.
As per the nbro results, since 1970, 36 out of the 57 landslides in Badulla District and 43 out of 71 landslides in Nuwara Eliya District have occurred near human settlements and agricultural lands. A wide variety of ground movements, such as rock falls, slope failure, and shallow debris flows can classify landslides. The flowing ground water in pores and fractures of loose rock and soil materials could produce an increase of weight, which cause a slump or earth flow. These haphazard development activities and inadequate attention to construction aspects have lead to landsides and consequently property damage and loss of life. Most landsides can be prevented if proper landslide essay in english investigations are performed in time. Landslide warnings have also been issued in Yatawatte, Rattota, and Pallepola of Matale district. . In some hilly Districts, in Sri Lanka, the National Building Research Organization (nbro) has already delineated areas according to the potential risk for development activities. Landslides range in size from a single boulder in a rock fall to a debris avalanche, which may have huge volumes of rock and soil capable of covering many kilometers. Do not return until the site has been inspected.
When rainfall or some other water source increases the water content of the slope the weakness is irritated, reducing the strength of the materials. Some times the trees are totally uprooted. Erosion creates steep slopes that make the downward and out word movement of rock and soil masses. There are generally three types of creep: (1) seasonal, where movement is within the depth of soil affected by seasonal changes in soil moisture and soil temperature; (2) continuous, where shear stress continuously exceeds the strength of the material; and (3). Mapping slide area Flash floods Land use maps. Or, if you prefer to keep them in the house for everyday use, make sure you know where to find them when an emergency occurs. As a result of that holes are created in the slopes. The rock and mud left over after a landslide may pick up anything in its path, such as trees, houses, and cars, causing bridges and tributaries to become blocked which causes flooding throughout its path.
273 words essay on Landslides
A landslide hazard zonal map is being prepared in 20 districts that have been identified as landslide prone to guide local decision makers in permitting constructions in such areas. Springs, seeps, or waterlogged ground in areas that are not usually wet. When construction is planned in any of these hilly areas, it is necessary to adopt prudent measures that would enhance the stability of the landmass and any structure built. Mostly in Sri Lanka small scale irrigation channels and drains are neglected. 1992 at Watawla Railway station is a typical example for the above causes. Over landslide essay in english 570 million years old) and they are made up of interlocking minerals. The landslides occurred in 3 Jan. Controlling of clearing of forests for firewood and timber would minimize the landslides up to a considerable extent. First aid kit. The WC is on the west of the HC and the VC on the east. The crystalline rocks are of Precambrian age (i.e. Two houses in Bogambara, Kandy have also been gravely damaged leaving one person seriously wounded.
This is the wet zone. Lateral spreading in fine-grained materials on shallow slopes is usually progressive. They often take place in conjunction with earthquakes, floods and volcanoes. In same instance, prior to implementation any such measures may need detailed studies and significant input from professionals such as geotechnical engineers and engineering geologists. Now the National Building Research Organization (nbro) is to issue new guidelines for development, construction and human settlement activities in all landslide prone areas. Similarly, in developing the road and railway network in the Hill County, early British engineers paid serious attention to the design and maintenance of culverts to evacuate excess water and minimize slope instability. Leaning trees, retaining walls, or fences. Creep is indicated by curved tree trunks, bent fences or retaining walls, tilted poles or fences, and small soil ripples or ridges. A relatives house). This should be prevented and also the prohibition landslide essay in english of rock blasting works on unstable slopes could minimize this problem.
Mapping lava flows, ash falls and lahars, map damage. This also paved the way of for landslides. Eventually these slopes were rendered barren and the process of erosion was set in motion. More specifically, it should be determined whether a landslide has occurred in solid rock, weathered overburden or colluviums, a clear distinction to make between the latter two conditions. The agriculture department has to form quick growing and deep-rooted trees. This is why one can notice landslides even in dense forest areas such as those on the knuckles Range. As a result of the rapid increase of population, more land was required for housing and cultivation. It is good, if you can make them aware the causes for landslide by providing a good knowledge about landslide. So propitiation of gem mining in unstable slopes could also minimize this problem. However, dry flows of granular material are also possible. As a result the actual man land ratio in these rural communities affected by landslides will be very much higher. Map amount, extent of damage.
Prohibiting the cultivation of the steeps of mountainous could be another mode of reducing the effects of landslides. Among the man made causes poor land management, depletion of forest cover, unsystematic drainage, silting water bodies on unstable hill slopes, road cuts (not well planed) and blasting operations. Forecasted damage including areas designated AS unsafe methods OF minimizing THE effects OF landslides As a first mode of minimizing the effects of landslides we have to identify and map out the vulnerable areas in the hilly regions. Areas that have not moved in the past. However, the homes built at the toe of steep slopes are frequently vulnerable to slides and debris flows that originate on property controlled by others. Get help with your essay today, from our professional essay writers! These are land use pattern, non-engineered construction, mining and quarrying, non-engineered excavation and deforestation leading to soil erosion. Retaining walls and rock lying should be constructed methodically and when constructing them you should take the necessary methods and instructions. Derana January 9, people have been evacuated to two shelters in Ella and Mahiyangana in Badulla district due to land slide threats. So the re-plantations in the created holes avoid the filling of rainwater.
Essay on Landslides in India - Worlds Largest Collection
Landslides are thus associated with surface or subsurface streams or water flows originating from the mountains. If they were unstable a landslide would have taken them to the bottom of that hillside a long time ago. Studies carried out in several areas in Sri Lanka and suggested that small landsides could be easily avoided by paying a little more attention during construction. Jointing is a common property of nearly all rocks of the HC and the presence of joints impart a degree of permeability to these crystalline rocks. Most of it falls within the wet and intermediate climatic zones, where the heaviest rainfalls are experienced and it is in HC rocks that nearly all landslides in Sri Lanka occur. Colombo Page THE areas prone TO land slides In the case of occurrences of Landslides in Sri Lanka, ten major districts have been identified as Landslide prone areas. For example, heavy rainfall occurred from 17 to 25 December 1957 in the north- eastern part of Central Highland and many stations had 500mm of rainfall. Advertisements: Heavy rain, floods, or earthquake shaking can cause landslides. Furthermore, vibrations from machinery, traffic, and even thunder may trigger failure of weak slopes. The failure starts suddenly in a small area and spreads rapidly. Sri Lanka is made up predominantly of crystalline rocks, which underlie about nine tenths. The processes and activities that cause landslides are frequently referred to as triggering conditions. Loud sounds that occur during an earthquake also cause landslides.
Among them are 30 Buddhist monks from the Mawalangala Aramaya. Geodynamic measurements of strain accumulation. During the last rainy season, hilly areas belonging to Matara, Galle and Hambanthota districts were severely affected by large-scale Landslides and slope failures. Their sole motive was to fulfill their needs. Have an emergency- evacuation plan and a kit of emergency supplies for your family. In order therefore to be able to delimit landslide prone areas and to improve our ways of predicting landslides and of giving early warming of their occurrence a proper understanding of the geology and geological structure of such areas is an essential pre requisite. The landslides are thus associated with accumulating and/or flowing water on or below the surface in mountainous terrains. The counter forming project should be encouraged.
A little over three years later, that was in may and June 1989, the landslide events surpassed all the earlier events in severity and magnitude, claiming more than 300 lives, rendering a large number of poor families homeless. Food Canned or dried food. Personal hygiene Items like toothbrush, soap, sanitary pads etc. Toilet paper and plastic bags for an emergency toilet vii. A torch and spare batteries. Advertisements: The landslides are simply defined as the mass movement of rock, debris or earth down and have to include a broad range of motions whereby falling, sliding and flowing under the influence of gravity dislodges earth material. This is hardly surprising given the mindless destruction of the countrys natural environment over the past few decades in the name of development and progress. Natural Triggers Human Triggers Removal of Support erosion at the base of a slope by streams, waves, glaciers excavation at the base of a slope or excavation on a hillside Removal of Vegetation forest fires timbering Addition of Moisture rainfall. An idealized slump-earth flow showing commonly used nomenclature for labeling the parts of a landslide. The shift in the ecological balance over the years due to environmental degradation has now made even once landslide free areas vulnerable today. Other main landsides occurred due to high rainfall are, Keenakelle (elevation 1433m) in the Buddlla District (annual rainfall 2644 mm), Ginigathena area in Nuwara Eliya district (elevation 762m) in (annual rainfall 5086mm) and Patulapana in the Ratnapura district (elevation. Tornadoes Now casts; local weather. These practice particularly the maintenance of culverts, and drains have been neglected in recent decades and it may be contended that this is an overriding reason for the increasing trend of landslides to day.
Therefore, occurrence of frequent Landslides and slope failures could be considered as the most significant natural disaster in Sri Lanka. Previous incidents The 1986 January landslides in â claimed 51 lives, rendering nearly 100 families homeless and affecting more or less all the seven landslide -prone districts of the hill country. The intricate system of irrigation channels that existed in the hill country during the last century undoubtedly served the dual purposes of irrigation as well as slope stabilization, thereby minimizing the occurrence of landslides. Furthermore in the case of overburden the depth to solid rock, the strike and dip of the rocks and of the joints should be analyzed. The landslides that we see today occur when natural processes or human activities disturb a stable slope. It has been mentioned that under conditions of soil saturation up to 80 of the total shear strength of a soil is attributed to tree roots. Based on research the nbro has also revealed that 90 percent of the recent landslides in the country was due to human activity. Http whyperlink ia More than 100 people lost their lives during May 2003 floods in the Ratnapura district when intense precipitation of more than 300mm fell within a period of few hours on unstable hill slopes. The slope instabilities observed in reservoirs constructed in landslide prone areas such as Kotmale, indicated the effects of the fluctuations of the reservoir level in the surrounding areas which was not adequately foreseen by the design engineers. Warn neighbors who might be affected. Find out if there have been landslides in your area and where they might happen again. The Precambrian rocks are subdivided in to three major units, namely the highland complex (HC the Wanni complex (WC) and the Vijayan Complex (VC).
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(ml) Get help with your essay today, from our professional essay writers! Landslides, slope failures and rock falls are frequent phenomena in these areas causing severe damages to life landslide essay in english and property. Why has Indian agriculture started a declining trend in food production? Creep is the imperceptibly slow, steady, downward movement of slope-forming soil or rock. Landslides Topographic and land use maps.