12 JUL 1970 ALAKNANDA FLOODS DEVASTATION

Recent and past floods in the Alaknanda valley: causes and consequences

Article (PDF Available) in Current science 105(9):1209-1212 · November 2013 with 165 Reads
Impact Factor: 0.93 ·

1st Naresh Rana
16.53 · Hemwati Nandan Bahuguna Garhwal University

2nd Sunil Singh

3rd Y P Sundriyal

4th Navin Juyal
Abstract
Uttarakhand Himalaya in general and Alaknanda and Bhagirathi valleys in par-ticular have experienced one of the worst forms of disaster in recent times (Figure 1). Flash floods are common in the Himalaya, but the kind of destruction witnessed this time was unparalleled in recent history. Houses collapsed like a pack of cards and the roads and bridges swept away in the turbulent flood waters. Probably the worst causality of the cen-tury was the destruction of Kedarnath valley. According to the data published in various national dailies, nearly 4000 people were either killed or lost, 2232 houses were damaged, 1520 roads in dif-ferent parts of Garhwal were badly dam-aged and about 170 bridges have been washed away. According to economists, the tourism industry in Uttarakhand will suffer a loss of ~12,000 crore rupees, which is around 30% of the state’s GDP. Over the years increased frequency and magnitude of flash floods in Uttara-khand Himalaya is worrying the inhabi-tants. Was it due to the commercial forest felling that was prevalent until around 1980s, or the recent rampant ter-rain tampering for hydropower projects? In order to appreciate the sensitivity of the terrain towards unusual weather events like cloudburst, let us look into the genesis of two major flash floods, viz. 26 August 1894 and 20 July 1970. These floods are reasonably well docu-mented 1–5 . The 1894 flood occurred well before the commercial forest felling ex-tended into the inner catchments of the Alaknanda, whereas the 1970 event oc-curred when the commercial forest fell-ing was at its peak in the Alaknanda valley. However, both floods owe their genesis to the breaching of dams created by landslides on the tributaries of the Alaknanda river, a common geomorphic expression during unusual rainfall events in the monsoon-dominated Himalaya 1,3 . On 6 September 1893, a tributary of the Alaknanda river called Birahi Ganga (Figure 1) was blocked by ~5000 million tonnes of rock mass that rolled from 900 m high valley flank. The debris blocked the river forming a lake 270 m high, 3 km wide at the base and 600 m wide at the summit 1,2 . It was estimated that the lake would have taken at least a year to fill. The dam would partially breach only after the water began to top-ple it, which would cause flash floods in the downstream till Haridwar. The untiring efforts of Pulford, the then superintending engineer and his team, particularly Pandit Hari Krishen Pant (district surveyor of Garhwal), helped to meticulously estimate the magnitude of downstream inundation. An excellent telegraph system was installed between Birahi Ganga and Haridwar for real-time monitoring and timely warning of the flood. Around May 1894, pilgrim traffic on the way to Kedarnath and Badrinath was diverted to the new pedestrian route
Discover the world’s research

100 million publications
2.5 million new publications each month
10 million members
Join for free

Discover more categories

RainfallFloodsLakesRiversWaterWatershed ManagementWatershed HydrologyClimate ChangeWater ResourcesHydrological Modeling
Figures

Figure
Enlarge
Full-text (PDF)
Available from: Naresh Rana
COMMENTARY CURRENT SCIENCE, VOL. 105, NO. 9, 10 NOVEMBER 2013 1209Recent and past floods in the Alaknanda valley: causes and consequences Naresh Rana, Sunil Singh, Y. P. Sundriyal and Navin Juyal Uttarakhand Himalaya in general and Alaknanda and Bhagirathi valleys in par-ticular have experienced one of the worst forms of disaster in recent times (Figure 1). Flash floods are common in the Himalaya, but the kind of destruction witnessed this time was unparalleled in recent history. Houses collapsed like a pack of cards and the roads and bridges swept away in the turbulent flood waters. Probably the worst causality of the cen-tury was the destruction of Kedarnath valley. According to the data published in various national dailies, nearly 4000 people were either killed or lost, 2232 houses were damaged, 1520 roads in dif-ferent parts of Garhwal were badly dam-aged and about 170 bridges have been washed away. According to economists, the tourism industry in Uttarakhand will suffer a loss of ~12,000 crore rupees, which is around 30% of the state’s GDP. Over the years increased frequency and magnitude of flash floods in Uttara-khand Himalaya is worrying the inhabi-tants. Was it due to the commercial forest felling that was prevalent until around 1980s, or the recent rampant ter-rain tampering for hydropower projects? In order to appreciate the sensitivity of the terrain towards unusual weather events like cloudburst, let us look into the genesis of two major flash floods, viz. 26 August 1894 and 20 July 1970. These floods are reasonably well docu-mented1–5. The 1894 flood occurred well before the commercial forest felling ex-tended into the inner catchments of the Alaknanda, whereas the 1970 event oc-curred when the commercial forest fell-ing was at its peak in the Alaknanda valley. However, both floods owe their genesis to the breaching of dams created by landslides on the tributaries of the Alaknanda river, a common geomorphic expression during unusual rainfall events in the monsoon-dominated Himalaya1,3. On 6 September 1893, a tributary of the Alaknanda river called Birahi Ganga (Figure 1) was blocked by ~5000 million tonnes of rock mass that rolled from 900 m high valley flank. The debris blocked the river forming a lake 270 m high, 3 km wide at the base and 600 m wide at the summit1,2. It was estimated that the lake would have taken at least a year to fill. The dam would partially breach only after the water began to top-ple it, which would cause flash floods in the downstream till Haridwar. The untiring efforts of Pulford, the then superintending engineer and his team, particularly Pandit Hari Krishen Pant (district surveyor of Garhwal), helped to meticulously estimate the magnitude of downstream inundation. An excellent telegraph system was installed between Birahi Ganga and Haridwar for real-time monitoring and timely warning of the flood. Around May 1894, pilgrim traffic on the way to Kedarnath and Badrinath was diverted to the new pedestrian route Figure 1. Map showing the Alaknanda and Bhagirathi valleys; red polygons show the approximate location of flood damage. Figure 2. Gohna lake during early 1930 (a) and 2008 (b).
Page 1
COMMENTARY CURRENT SCIENCE, VOL. 105, NO. 9, 10 NOVEMBER 2013 1210 which was constructed much above the anticipated flood level. Similarly, eight suspension bridges between Chamoli and Haridwar were dismantled in order to protect them from being washed away from the anticipated flood. As predicted, on 25 August 1894, water began to trickle over the dam and at midnight the dam was partially collapsed, sending flood surges downstream. The flood lasted until the morning of 26 August causing unprecedented damage to the property around Srinagar town; however, no loss of life was reported. During July 1970 (after 76 years), the Alaknanda valley witnessed the second major flood. This was attributed to a cloudburst on the night of 20 July 1970, on the southern mountain front in the Alaknanda valley (between Joshimath and Chamoli). According to an estimate, flood transported about 15.9 × 106 tonnes of sediment within a day6. The catastro-phe was so large that it wiped out the leftover of the 1894 Gohna lake (Figure 2). In addition, a roadside settlement between Pipalkoti and Helong called Belakuchi in the Alaknanda valley was washed away along with a convoy of 30 buses by the roaring Alaknanda river. However, around 400 pilgrims en route to Badrinath were saved due to the alert-ness of a police constable who guided them to run uphill7. Besides, 13 bridges were swept away and far away at Harid-war, around 10 km stretch of the Ganga canal was clogged with sediment and uprooted trees. This time again Srinagar town had to bear the brunt, virtually the lower town was completely destroyed by the flood. This flood was widely debated in the country. There were people who were of the opinion that it was independent of deforestation. According to them, defor-estation in the Himalaya has a trivial effect on erosion, run-off and thus flood-ing. Although in minority, there were groups of people particularly the local inhabitants, who strongly believed that the flood owed its genesis to the large-scale commercial forest felling in the preceding years. In fact, recent scientific studies support the suggestion that flood and deforestation in the Alaknanda valley are closely related3,4. The 1970 Alaknanda flood was responsible for raising the ecological consciousness of the people that finally resulted in the birth of the now world-famous Chipko movement in 1973 (ref. 3). Figure 3. a, Profile taken along the left bank of the Alaknanda river at Srinagar indicat-ing the highest flood levels (HFLs) measured using differential GPS. b, Photograph of ITI building partially buried under mud. c, Photograph shows the HFL of 1970 and 2013 floods near ITI Srinagar (Garhwal). Figure 4. a, Cross profile from river bed to Bhainswara village showing HFLs, b, Pho-tograph of past 600 year flood deposit at Bhainswara. Dotted yellow line shows the height of the 1970 flood. c, Sediment deposited after the June 2013 flood (photograph taken on 20 June 2013). Note that the 2013 flood deposit over topped (~4 m) the 1970 flood sediment.
Page 2
COMMENTARY CURRENT SCIENCE, VOL. 105, NO. 9, 10 NOVEMBER 2013 1211 Figure 5. Extent of flood inundation around Srinagar (marked with red dashed line). Summarizing the above incidences, it can be suggested the flood of 26 August 1894 was a natural landslide-induced dam burst phenomenon and hence antici-pated well in advance thus precious lives were saved. On the contrary, the 1970 Alaknanda flood which caused large-scale damage to the life and property was undoubtedly conditioned by the large-scale commercial forest felling (anthro-pogenically induced); hence we failed to predict it. Geological evidences of past floods (e.g. slack water and palaeoflood deposits) are scanty; however, in some sheltered locations around Srinagar, Bhainswara and Devprayag (Figure 1), at least 1000-year-old history of floods in the Alak-nanda valley can be reconstructed4,5,8. Wasson et al.5 concluded that during the last 600 years, the floods were an out-come of the natural dam bursts in the upper Alaknanda catchment and the 1970 event was the highest in magnitude. But this record seems to have been broken by the recent flood. It was found that (i) the 16 June 2013 flood deposits invariably overlie the 1970 flood sediment and occur at an elevation of 536 m at ITI to 516 m at Bhainswara (Figures 3 and 4), implying that June 2013 flood was the highest in the Alaknanda valley at least during the last 600 years. (ii) Flood sediments are incised into two surfaces, e.g. at Bhainswara before the Alaknanda river attained its pre-flood base level, implying that the flood peak receded in two distinct pulses (Figure 4). On the basis of field observations, the vertical and lateral extent of flood is prepared (Figure 5), which can be used as a refer-ence map for preventing any construc-tional activity below this zone in a fast-growing Srinagar town. According to Wasson et al.5 all of the large floods in the Alaknanda river catchment appear to be the result of land-slide dam bursts rather than glacial lake bursts, and these are likely to continue and possibly worsen as the monsoon intensifies over the next century. The floods generated by the breaching of landslide-induced dams carry large amounts of sediment that may dominate the sediment yield in the Himalaya9. Ac-cording to Korup10, the sediment yield associated with the breaching of land-slide dams is second only to post-volcanic eruption yields, but is greater than yields from glacier lake outburst. The past floods (at least 1894 and 1970) were associated with landslide-induced dam breaching; the current flood does not seem to fit into such a conventional cate-gory. It has now been demonstrated3,4 that deforestation coupled with cloud-burst in the upper Alaknanda catchment was the major factor responsible for the 1970 flood. Commercial deforestation in the region is banned since 1980; hence deforestation cannot be implicated for the recent flood. If the rivers were not blocked by landslide dams, because breaching of such dams not only sends short-lived, high-intensity flood surges, but also transports enormous sediment load into the lower reaches9,10, how was such a large quantity of sediment flushed by the Alaknanda river during 16 and 17 June 2013? In case of the upper catch-ment of the Mandakini valley (around Kedarnath) natural pile of sediment was available, which was left by the receding glaciers (moraines). When the cloudburst occurred, the sediments dominated by glacier boulders were lifted by the high-density water flow and transported down the valley towards the temple town de-stroying everything on its way. Shall we blame the debris flow or the obstruction caused by the recent pattern of construc-tion that mushrooms around the temple? Over the years we have occupied every space for making commercial settlement around the temple defying the law of the nature. Figure 6 a shows how the Kedar-nath valley looked during 1882 (ref. 11). When we compare it with the 2008 pho-tograph, one can see the large number of commercial settlements in the Kedarnath valley (Figure 6 b). Coming back to the Alaknanda valley, in absence of large-scale landslides during the recent flood and the glacier deposits located far up in the rain-shadow zone, it is pertinent to speculate that the sediments were locally generated by unnatural processes. Ac-cording to an estimate, nearly 11,100 km of road has been constructed during 2000–2012 (ref. 12) and currently 45 hydropower projects are operational and
Page 3
COMMENTARY CURRENT SCIENCE, VOL. 105, NO. 9, 10 NOVEMBER 2013 1212 Figure 6. View of Kedarnath valley during (a) 1882 and (b) 2008. 199 are at various stages of develop-ment13. Considering the extent of human interference, it is likely that the terrain sustainability is precariously bal-anced. A minor perturbation would have been enough to generate a cascading ef-fect on the terrain instability. And the impetus was given by the unusual rain during 16 and 17 June 2013, which caused the Himalaya to respond violently against the unscientific human interfer-ence. Let us not blame nature alone; unusual rainfall events have been taking place in the Himalaya. But the Himalaya has not witnessed such clogging of its rivers by the concrete structures. Not only this, the re-peatedly damaged banks (during 1894 and 1970 flash floods) have been reoccupied at most of the places. In the past nature warned us not to venture into areas that are flood-prone. But we greed ignored such warnings; we occupied the river banks and had to pay dearly this time. It was nature’s fury indeed to begin with, however, the tragedy was amplified by human folly. 1. Holland, T. H., Report on the Gohna Landslip, Garhwal, Selections from the records of the Government of India in the Public Works Department: CCCXX-IV(324), Office of the Superintendent of Government Printing, Calcutta, 1984. 2. Pal, S. K., Geomorphology of River Ter-races along Alaknanda Valley, Garhwal Himalaya, BR Publishing Corporation, Delhi, 1986, p. 158. 3. Kimothi, M. M. and Juyal, N., Int. J. Remote Sensing, 1996, 17, 1391–1405. 4. Wasson, R. J. et al., J. Environ. Man-age., 2008, 88, 53–61. 5. Wasson, R. J., Sundriyal, Y. P., Chaud-hary, S., Morhtikai, P., Sati, S. P. and Juyal, N., Quaternary Sci. Rev., 2013, 77, 156–166. 6. Kumar, G. and Shone, S. K., In Proceed-ings of the Seminar on River Valley Pro-jects, Roorkee University, Roorkee, 1970, p. 7. 7. State of India’s environment: a citizen report. Center for Science and Environ-ment, New Delhi, 1991, p. 166. 8. Srivastava, P., Tripathi, J. K., Islam, R. and Jaiswal, M. K., Quaternary Res., 2008, 70, 68–80. 9. Brunsden, D. and Jones, D. K. C., In The International Karakoram Project, Vol. 1 (ed. Miller, K. J.), Cambridge University Press, 1984, pp. 383–388. 10. Korup, O., Earth-Sci. Rev., 2012, 112, 115–125. 11. Grieshbach, C. L., Geological Survey of India, Ministry of Mines, Government of India – photo archive, 1882–1883; http:// http://www.portal.gsi.gov.in/portal/ 12. Public Work Department Uttarakhand; http://www.pwd.uk.gov.in 13. Uttarakhand Jal Vidyut Nigam; http:// http://www.uttarakhandjalvidyut.com ACKNOWLEDGEMENT. We thank the Department of Science and Technology, New Delhi for financial assistance vide grant num-ber SR/S4/ES-416/2009(G). Naresh Rana*, Sunil Singh and Y. P. Sundriyal are in the Department of Geo-logy, HNB Garhwal University, Srina-gar-Uttarakhand 246 174, India; Navin Juyal is in the Geoscience Division, Physical Research Laboratory, Navrang-pura, Ahmedabad 380 009, India. *e-mail: naresh_geo@yahoo

1 result (0.35 seconds)
Stay up to date on results for in 1970 floods in uttarakhand of alaknanda river and destruction.

Create alert

Help Send feedback Privacy Terms
About 4,810 results (0.59 seconds)
Dahisar West, Mumbai, Maharashtra – From your Internet address – Use precise location
 – Learn more
Help Send feedback Privacy Terms

 

 

 

 

 

 

 

Advertisements

Author: bcp211

BUSINESSMAN AND AGRICULTURIST

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s