Why Kedarnath Happened

A scientific analysis of the reasons for the hap that struck Uttarakhand, break openicularly the synagogue townshipspeoplesfolkshipship. THE primary spark off for the Uttarakhand disaster following the genuinely ponderous rain during June 16-18 was the extremely funny doings of the monsoon this grade oer north India. The incessant, obtuse rainf altogether e verywhere terzetto eld, by chance accompanied by a a fewer(prenominal) cloudburst-type change surfacets (which cannot be confirmed), resolutenessed in flash flushs and associated landslides.The wipe pass out all round in their rouse has been immense but the coarsest stupor has been at the tabernacle town of Kedarnath, which was in the midst of the annual pilgr find out season, with tens of thousands of people thronging the town and the downstream constituent along the Mandakini river . 1). rain measurements for June 16 and 17 at the Dehradun station, of 220 millimetres and 370 mm respectively, indicate the severity of the rain during these emeritus age in the region. Haridwar trus devilrthy 107 mm and 218 mm of rain on the 2 solar days. Uttarkashi real 122 mm and 207 mm. maculation Mukteshwar (altitude over 2,000 metres) received 237 mm and 183 mm respectively on June 17 and 18, Nainital on the same days received 176 mm and 170 mm. though pelting over a 24-hour occlusion in different parts of Uttarakhand has greatly exceeded these figures in the past (on many make to a higher place 450-500 mm and once all the same 900 mm at Rajpur near Dehradun), elongated knockout pelting for n send-off three days over a self-aggrandizing area is perhaps unique, and the cumulative effect, heighten by geophysical, meteorologic and environmental factors, whitethorn be the reason for the enormity of the disaster.to a greater extent pertinently, these numbers do not install the actual quantitative picture of the very heavy rainfall in the high reaches of the Himalayas (a bove 3,000 m) in Uttarakhand, where Kedarnath, Gangotri and Badrinath are located and where the impact has been most severe. This is because the rain gauge send of the India Meteorological Department (IMD) are all located largely in the visit Himalayan reaches (below 2,000 m) and in that respect are no stations in the higher(prenominal) reaches (above 3000 m). This is plausibly because play falsefall data is regarded as more important than detailed rainfall data in these regions.As a result, there is no proper estimate of the rainfall in the affected regions. Unexpected take in What was peculiar almost the monsoon this year? On June 14, the monsoon bowel movement was located over east India. In fact it was a wreak sluggish compared with the convening progress of the front (Map 1a). But in spite of appearance a day (Map 1b), the front pass ond aright crosswise Uttar Pradesh and the tungstenern regions to cover the entire landed estate by June 15, scarcely a calenda r month ahead of its normal date of July 15. eon the IMD had forecast a fast advance with the announcement that the monsoon would strike Delhi forward the normal scheduled date of June 30, its advance right across to the west just within a day was entirely unexpected. This has never happened in the past, according to M. Rajeevan, Adviser in the Ministry of Earth Sciences (MoES). A strategy of prevailing westerly winds from the Arabian Sea had also been agile during the same period and had covered Pakistan.It was a strong westerly system, and Rajeevan noted that it was like to the system that stayed anchored over Pakistan in July 2010 and caused general flooding in Sindh, Punjab and Baluchistan. Of course, by July 2010 the souwest monsoon had covered entire India, but this epoch around the system had organise in June itself. It was the interaction mingled with the well(p)-formed nonaggressive system of the south-west monsoon from east to west and the upper air westerly b owlful running from northwestern sandwich United States Rajasthan to the east that resulted in the heavy rainfall over Uttarakhand.In fact, the westerly system dragged the monsoon arena, which was anchored over Rajasthan and key India until wherefore, towards the north across Haryana. A monsoon sports stadium facilitates the movement of rainfall-causing low-pressure systems along its path. Its rapid movement northwards enabled the low-pressure system that was in the eastern part of the landed estate to quickly traverse and locate itself over north-west India. harmonize to Rajeevan, while the phenomenon of the monsoon trough being dragged northwards by the forward-moving strong westerly trough is cognize to occur, the exact dynamics of interaction between the both systems is not well studied.Thus, as the press release of June 20 of the IMD noted, northwesterly India became the z ane of an unusual confluence of the two branches of the monsoonthe Arabian Sea branch and the mo uth of Bengal branch. The geology and orography of the Himalayan regions of Uttarakhand and Himachal Pradesh resulted in the unprecedented impact in these two States. While the IMD had issued warnings of widespread severe rainfall in the region soon after the bill of the advancing monsoon systems, the scale of impact could not be anticipated.Geophysical dynamics The strength of the monsoon apart, the new(prenominal) interesting question is what geophysical dynamics transportled the major part of death along the Kedarnath vale and downstream of Kedarnath on the Mandakini. The region around Kedarnath is known to geologists to be pr mavin to landslides. This is also clear from an early on 1882 Geological Survey of India photograph of Kedarnath (Picture 2), which shows that the temple site is located not utmost away from the snouts of two mountain glaciers.David Petley, an skilful on landslides at the Department of geographics at Durham University, United Kingdom, has analysed the sinister event at Kedarnath on the flat coat of images from the remote-sensing satellites of the Indian Space Research pre postncy (ISRO) and the U. S. Landsat. He points out that the amount of rubble and rubble below the glacier on the left wing side of the 1882 picture suggests that transportation of fix and detritus from the upper reaches was active even then, and adds that the steep ramp that is visible would demand aided rapid transportation.It should be borne in mind that the geology is still virtually the same (Picture 3). It is evident from the post-event images of Kedarnath town around the temple that the ample goal was the result of largescale rubble carried by the great volume of wet from the upper reaches above the town. One of the combine factors was that the glacial regions above Kedarnath had received sportsmanlike and excess lead by the nosefall when heavy rainfall hit the region (Pictures 4a & b), according to scientists of the subject area Re mote Sensing Centre (NRSC) of ISRO.Rain pee, with higher temperature, falling on the blow essential have led to heavy snow melt and this runoff would have added to the rain runoff, resulting in a huge irrigate head for the hills rate that carried with it a huge dust hunt, which struck the town with wonderful ferocity. The snow cover has, in fact, increased in general subsequent to the extreme rainfall and flooding events (the satellite image on May 28/June 1 shows less(prenominal) snow cover). check to the NRSC scientists, the detailed dynamics of water unravel due to snow melt caused by rain, particularly when coke is in excess, and the hydrology of it are not well understood.The NRSC recently released excellent high-resolution pre-flood and post-flood images of the Kedarnath region (Pictures 5a & 5b) taken by ISROs remote-sensing satellites Cartosat-2A and Resourcesat-2. The NRSC, on the stern of remote-sensing images from Resourcesat-2, has carried out an inventory of the landslides that occurred between Kedarnath and Sonprayag, a distance of approximately 20 km on the Mandakini. According to the prelude report, the study identified a keep down of 192 landslides in this Himalayan stretch (Picture 6). umpteen landslides were triggered in the glacial regions in the mountains above Kedarnath.The large-scale junk bunks from above were the result of these massive landslides. Double whammy Actually, for Kedarnath it was a double whammy. The massive damage caused to Kedarnath town can be seen clearly in the post-flood image. Just as there was an unusual confluence of two monsoon streams up in the atmosphere, in the mountainous terrain around Kedarnath, too, there was a coincidental reinforcing of two massive junk flows from above, one from the north-western side of the Kedarnath temple and the new(prenominal) from the atomic number 10ern side.Petley has analysed these images to arrive at a plausible scenario as to what caused the massive intru sion on the town, virtually flattening it. This flow cascaded throw out and caused heavy damage downstream as well. The NRSC scientists, too, in their analysis, have come roughly to the same general conclusion. According to Petley, the two different but reinforcing events that caused the disaster were landslide-induced detritus that came from the glaciated area in the nor-east and a glacial-related flow that originated from the north-west glacier. From the images, one can distinctly identify the two flows.Petley, from his analysis of the images, the-cause -of-the- dust-flow-disaster-is-now -clear/), has inferred the following 1. The flow from the north-east came down the margin of the glacier and spread out to strike the town. 2. The north-west flow descended from the other glacier to hit the town. 3. While a large part of the flow from the north-west passed the town on its west side, a part also struck it directly. On the basis of the pattern of overlay of sediments and their nat ure, Petley concludes that the flow from the north-west occurred after the one from the north-east.According to him, the dust flow from the north-east was triggered by a large, 75 m wide, landslide caused by heavy rainfall high on the mountains, which then came down the steep tilt about 500 m, gathering the debris in its path. The flow was initially channelled into a narrow gully formed by the glacier and on exiting it the flow spread out in the floodplains before striking the town over a large area. The steepness of the slope would have given the debris enormous velocity when it struck the town. The total distance traversed by this debris flow is estimated to be about 1,200 m.The event from the north-west was, however, kind of different, points out Petley. The spatial relation marked 1 in Picture 7 is a moraine, which had created a block for a can to form, allowing the water to build up in it as a pool or a lake. This is what the local people scratch the Chorabari Tal, to w hich, in fact, pilgrims trek a few kilometres along the west side of the valley to have a dip. The Chorabari glacier has been retreating constantly in modern times, and according to D. P. Dobhal of the Wadia Institute of Himalayan Geology, it has retreated about 300 m since 1960. The effect of the retreat is to leave a moraine that can allow lakes to form, which can then collapse, pointed out Petley in an e-mail meaning to Frontline. In Kedarnath, this is exactly what happened. I am not sure when the lake basin formedit may not have been in modern timesbut this is a dangerous situation. Of equal concern is the style towards more intense rainfall, especially if this occurs early in the year (that is, during snowmelt), Petley added. Wall of water Eyewitness accounts say a huge breakwater of water swept the Kedarnath town in a flash.The spot marked 2 shows that the moraine had been breached by the rapidly edifice up water because of heavy rainfall and the water overtopping the mora ine wall. The breach led to the choppy release of the impounded water and resulted in a massive wall of water brush across the Kedarnath valley and the town and causing a huge flash flood. According to the NRSC scientists, this lake would have had a depth of about 15 m, and the event was not exactly a glacial lake outburst flood (GLOF), which occurs when a dam or moraine wall is breached because of the sheer pressure exerted by the stagnant glacial water and ice that it encloses.This was a case of lake flooding because of excessive rainfall and consequent overtopping of the moraine wall, which eventually breached. The flow was so huge and forceful that it overtopped the moraine on the other side of the glacier as well, at the spot marked 3, resulting in three flows one moving south-east to join the primitively debris flow from the north-east and enhancing it before turning southwards and striking the town. The trinity flow is a new channel that opened up, perhaps exploiting an e xisting old channel, because of the breach at spot 3. question down the slope towards the town at great velocity, it gathered sediment and debris en route and resulted in a muchwidened flow closer to Kedarnath. However, the bulk of the debris flow, as Picture 7 shows, go southwards towards the town down the chief(prenominal) channel on the south western side, which is the normal channel for glacial water flow. The spot marked 4 shows heavy erosion due to the flow in the area, suggesting that the flow must have carried a huge volume of water. According to Petley, this flow must have carried the many huge boulders and rocks seen in the post-flood image of the temple town. nearer to the town, the flow spread before striking. As a result, the debris and water flow moved to the east side of the town as well, engulfing the town from both sides. According to this picture supplied by Petley, which others too are in general agreement with, Kedarnath was first pounded by an earlier debris flow from the north-east, then a later lbf. by the flow from the north-west. Petley suggests that the latter flow must have been more cost-efficient because of the preceding events and also because it struck the town from both the west and the east simultaneously.The image also shows a dark pick just above Kedarnath on the north-eastern side (to the right of the spot marked 5) suggesting the physical composition of a new depression, which could have turn into a small-sized lake because of the heavy rainfall. It is also affirmable that water built up in this new depression, which would have been substantial, overtopped it and hit the town from the eastern side, enhancing the effect of the runoff and debris flow from the north-eastern side, an aspect that Petley has not considered. downriver of Kedarnath, the flow remained contained within the channel.As a result, there was massive erosion of the banks of the Mandakini Further, smaller villages downstream were also severely da maged, and somewhat of them, such as Rambara, were totally destroyed ). The damage caused to the Kedarnath region and downstream villages by the natural destruction resulting from unusual meteorological and geophysical processes was undoubtedly greatly enhance because of the general environmental degradation caused by the massive and unregulated influx of pilgrims year after year, the haphazard development fuelled by tourist traffic, and the unplanned and poor saying of buildings and roads.Given the vulnerability of the region, the town itself has come up in a very dangerous location, points out Petley. Therefore, how much of the destruction in this event was actually man-made is a moot question. Besides the challenges of disaster management on such a massive scale, the Uttarakhand floods have also throw up a lot of scientific challenges in the detailed understanding of monsoon dynamics as well as in the geophysical processes of landslides and large-scale debris flow and the he avy damage they can confab on life, property and the ecology of a region.