Issues in Mountain Development is a series released from time to time to brief planners,
development workers, researchers, and donors on recent trends, findings, and issues
affecting mountain development. The papers in this series can be quoted with due
acknowledgments. Comments are welcome.
Habitat and Hazards in
the Himalayas of Nepal
The mountains present more hazards than the plains because of their verticality and
fragility. Taking examples from Nepal, this paper establishes that current, increasing
interventions have augmented the magnitude of damage incurred in the mountains. Hence the
need to take environmental impacts into account when planning infrastructure in mountain
areas. This would imply a knowledge of the structure of the terrain on the part of the
builder.
The Context
Nepal lies in a tectonic zone where the mountain-building process still continues. As a
result, the area is subject to landslides, avalanches, glacial lake outburst floods,
flooding, and a host of indirect or `creeping' hazards. Thus the mountain environment,
although often referred to as `fragile', is actually quite dynamic and `volatile'.
Modern communications have enabled the compilation of improved public records of hazard
events, but the introduction of modern infrastructural facilities that are built without
taking into consideration potential hazards has meant that the probability of extensive
damage has increased. This is not a development paradigm but rather a development paradox.
Development interventions in Nepal started in the mid-fifties only and awareness of
deterioration in natural mountain habitats increased from that time. The spread of modern
medicine and increasing development interventions were not accompanied by concomitant
advances in planning in Nepal. This meant that awareness of the desirability of limiting
families to within sustainable limits did not become part of the received wisdom in a
general sense. The increases in population that occurred along with development
interventions soon meant that agriculture was extended on to marginal lands; lands that
were not capable of providing yields that were commensurate with the labour and investment
expended on them. The result was, as we see today, poverty, increasing outmigration of
families from the hills and mountains on a permanent basis, and increasing temporary
outmigration of men (and now, all too often, women) to seek casual labour in an effort to
supplement the meagre incomes from the rapidly deteriorating farmlands.
At the same time, interventionist policies dictated investments in mountain roads and
other types of infrastructure, but without the accompanying concern about
environmentally-friendly construction. The more localised disasters increased because
little allowance was made in engineering techniques for how hazard-prone an area might be.
Thus, we have the two interfaces of habitat and hazard - the hazards
inherent in the natural environment and the hazards augmented by the public infrastructure
built without making allowances for possible hazards. At the same time, ever present are
the dwellings and structures that have been built locally and which themselves are prone
to hazard. Poorly-constructed dwellings can, at a time of natural disaster, substantially
increase the number of lives lost. However, there is no doubt that the people of the
Himalayas have lived with such disasters in the past and have coped. They devised
indigenous responses to the crises produced by their awesome (and sometimes cruel)
environment. What they are called upon to deal with now is a rapid, modern intervention in
infrastructural construction; an intervention that has increased the magnitude of the
crises with which their traditional responses can no longer cope.
| Although
historical records leave behind some impressions of the impacts of the bigger disasters,
there are scores of smaller events that remain unrecorded or, at very best, within the
folk memory of a village or region. |
A cursory comparative
assessment of the three major earthquakes in Nepal between 1934 and 1988, and glacial lake
outburst floods, between 1935 and 1985, shows a decrease dwellings and other buildings; to
carry all this out, economic growth is, of course, a sine qua non. Needless to say, some
indigenous buildings have their strong points, otherwise the population would not have
continued to build the same type of dwelling in the same locations, generation after
generation; hazards to person and property have certainly not decreased over the
centuries. |
|
|
| Landslides and Flood Damage (N.B.
10-25% of hill roads following river valleys are completely washed out every four to five
years through a combination of floods and landslides.)
- 1979: The Bijayapur Khola (30m) and Karra Khola (60m) bridges (cost Rs 8 million)
- 1981: 27km of the 114km Arniko Highway was damaged (cost Rs 62 million)
- 1983/84: Dharan-Dhankuta Road damage (500m) (cost Rs 23 million/km)
- 1987: 350km of road damaged, 41 bridges damaged of which 15km of road and 3 bridges were
completely destroyed; the worst portion was the Charnawati landslide damage to the bridge
and road(Rs l90 million) (cost between Rs 520 to 730 million in total)
- 1991: Seti Bridge collapse, Pokhara
- 1993: damage to the Prithvi Highway, Tribhuvan Highway, E-W highway, Phidim-Taplejung
Highway, Bardibas-Sindhuli road, Dhalkebar-Birtamod road. Floods were devastating, along
the Tribhuvan highway 2,000 landslides occurred (over 200 of them major) and the road was
washed out in 20 places. Traffic was stalled between Kathmandu and the Terai for 28 days.
Road rehabilitation costs from 1979 to 1993 were Rs 2,250 million or $US 50 million.
The 1993 floods and landslides alone caused the following damage.
- 1,612 people lost their lives
- 85,00 families affected through loss of or severe damage to their homes
- extensive areas of cultivated land were damaged and crops destroyed
- damage to the Bagmati barrage (Rs 50 million)
- damage to the Kulekhani* hydro project (Rs 200 million)
- destruction of bridges at Malekhu, Belkhu, Agra Khola, and Bhainse
* This project had been damaged before by landslides in 1984. Even considering the
fluctuation in dollar exchange rates over the years documented here (from approximately 45
to 55 rupees per U.S. Dollar), the cost in terms of human lives and destruction to both
public and private property is enormous.
Sources: Deoja 1994, Dhital et al. 1993, and Upreti and Dhital 1996. |
Traditional buildings are vernacular mostly (non-engineered) and are
often built with mud and timber and quite often, in the villages, with wattle and daub.
Since damage data on buildings in Nepal in the past were never specific, it is difficult
to project a damage ratio for them (UNDP/UNHCR 1994). As with the mountain risks and
hazards themselves, damage ratios of Nepali buildings in the near future can only be
modified within the limitations of the structures themselves. The possibility of damage is
not going to go away, at least not in the short term.
Despite awareness about the importance of safe habitat in hazard-prone areas, people in
the mountains continue to build and rebuild in the same areas for generation after
generation. Never was this more acutely brought home than in November 1995. Several days
of continuous rainfall triggered life-threatening hazards in several areas of Nepal.
One such spot is Bagarchhap in the Manang district of Nepal, an important transit point
to trekking spots like Annapurna and Muktinath. It rained from the 9th to the 11th of
November and then a debris flow occurred on November the 10th upstream from Bagarchhap
bazaar. At 18.30 on the 10th the banks of the stream also burst bringing down a tremendous
amount of debris flow. There was a sound like thunder and large boulders of gneiss and
schist came down, destroying 14 houses. Again, on the 11th of November, at half-past
twelve, the thunder was heard again and more debris came down, moving left from the head
of the village. Of 70 foreign trekkers staying there that night, 9 were killed, 11
Nepalese also lost their lives; 6 of them were porters and cooks attached to the trekking
parties. Of the 14 buildings destroyed, seven were lodges and two shops. But the fact is,
in 1968, a similar debris flow took place in the same area and the whole village was
destroyed; after some months the people returned and settled on the debris fan (WIDPTC
1995).
The Nepalese say that the extraordinary beauty of the Himalayas was created by the gods
to make their inhabitants forget the excruciating hardship and ever present danger of
survival in loss of human lives and in damage to domestic habitats (Box 1). However, no
direct comparison can be made of separate events without taking into consideration the
various associated factors. On the other hand, the cost of damage to public infrastructure
from floods and landslides (Box 2) also incurs enormous fiscal and psychological setbacks
to a developing country like Nepal.
| Earthquakes 1934
earthquake ( Jan 15th)-8.4 on the Richter scale
- 8,515 deaths (4,296 in Kathmandu)
- 80,890 houses completely destroyed
- 20,7248 buildings badly damaged
1988 earthquake (Aug. 21st)-6.6 on the Richter scale (eastern Nepal)
- 717 deaths
- 23,000 homes completely destroyed
- 65,00 homes severely damaged
1980 earthquake (July 29) - 6.5 on the Richter scale
- 178 deaths
- 40,000 houses destroyed
This earthquake was restricted to a 40,000sq.km. area which included Bajhang, Bajura,
Darchula, and Baitadi (districts in far west Nepal). |
Glacial
Lake Outburst Floods Nine major glacial lake outburst floods took place between 1935
and 1985, of these 3 were on the Bhote Koshi*, a tributary of the Sun Koshi (1935,1964,
&1981); 2 on the Arun River* (1964 and 1982); 1 on the Trisuli River* (1964); 1 on the
south slope of Ama Dablam (1977); 1 on the Barun Khola (1981); and the Bhote Koshi/Dudh
Koshi/Namche GLOF (1985). Of these, the most complete records are for the latter. In that,
5 persons died, 30 houses were destroyed, and the Namche Hydel project was destroyed . The
cost of the damage to the latter was Rs 40 million (US$ 800,000).
* These originated in Tibet, China. Source: Ives 1986 and Deoja 1994 |
However, should an earthquake the size of the 1934 earthquake take place today, and
experts believe that a much bigger one could be in the offing (Bilham et al. 1995), the
additional infrastructure would mean much greater losses in life and property.
The proneness of the Himalayas to hazards is awesome. The risk the Nepalese mountain
farmer takes when she or he plants crops on carefully tended terraces at breath-taking
heights and on painfully steep gradients can be in no way assessed in comparison to the
risk an average European might take in crossing a busy road. In the latter we are dealing
with risks to the individual and in the former to whole communities. In this environment,
even rainfall is a risk (Chalise et al. 1995).
However, it is landslides that the people of Nepal are most familiar with, every
monsoon triggers more and more, especially in areas recently excavated to add more
infrastructure (Upreti 1995). So what can be done to make the human habitat safer?
Hazard mitigation involves both public infrastructure and private property. Concern for
the risks that the establishment of public infrastructure posed to mountain communities
led to ICIMOD introducing a mountain risk engineering programme to train engineers mainly
in engineering geology. The philosophy behind this being that additional impacts caused by
construction are bound to accelerate natural destabilisation and that, therefore,
infrastructural development cannot be the domain of a single discipline. A programme on
Mountain Risk Engineering commenced in 1988. In 1991 a handbook was published (Deoja et
al. 1991) which is in actual fact a comprehensive text on many of the issues related to
building roads.
ICIMOD's Mountain Risk Engineering project is in its third phase. Important as public
infrastructure and methods of building might be, ICIMOD realises that hazards in the
mountains are a natural process that cannot be changed, mitigation is the most that can be
hoped for. In this respect, the Centre, under the Landslide Hazard Management and Control
Project, has been documenting work on mountain risks and hazards, and particularly in
their mapping, management, and control in China (Li Tianchi 1996), India (Thakur 1996),
Nepal (Upreti and Dhital 1996), and Pakistan (Malik and Farooq 1996).
On the part of the Government of Nepal, there has been a realisation for some time now
of the hazards that some indigenous dwelling structures and poor building materials pose
to the inhabitants; particularly when this hazard is compounded with the natural hazards
described above. Extensive surveys of building materials, foundations, walls, floors, roof
types, and openings in some hazard-prone areas have taken place (UNDP/UNHCS 1994) in
preliminary attempts to design buildings that can better withstand mountain seismic
hazards. Vulnerability of rural buildings was examined in order to identify weak points
inherent in construction practices and materials. The strategy in mind is to formulate
policies and plans for upgrading existing on the highest mountains on earth. In light of
what we know about the recurring danger of serious hazards in this habitat, they are
obviously right.
| The
capacity of human beings to forget, or set aside, the negative is quite frightening; it is
particularly frightening when one considers the astounding mountain folds of the
Himalayas, their young rocks, and unstable terrain. |
With this in mind perhaps, the
government has been busy over the last decade preparing a National Action Plan along with
activities connected with the United Nations International Decade for Natural Disaster
Reduction (HMG 1995). The plan has both a `Disaster Preparedness Action Plan Matrix and a
Disaster Response Action Plan Matrix'. The only problem with these is that action on the
former was scheduled to begin in 1996 with institutional arrangements and formalisation of
organisations and structures and action on the latter in 1997 only (HMG 1995). Sad to say,
these activities, coming as they do in the latter third of the Disaster Decade, were not
in time for the devastating floods of 1993 or for the Bagarchhap Landslide in late 1995.
Nevertheless, the response to crises in this Himalayan land has always been remarkable,
given the resources at its disposal. |
References
Bilham, R.; Bodin, P; and Jackson, M., 1995. 'Entertaining a Great Earthquake in
Western Nepal. Historic Inactivity and Geodetic Test for the Development of Strain'. In
the journal of the Nepal Geological Society, Vol. 11 (sp. Issue) 1995.
Deoja, B.B., 1994. Sustainable Approaches to the Construction of Roads and Other
Infrastructure in the Hindu Kush-Himalayas. Occasional Paper No. 24. Kathmandu: ICIMOD.
Dhital, M.R.; Khanal, N.; and Thapa, K.B. ,1993. The Role of Extreme Weather Events,
Mass Movements, and Land Use Changes in Increasing Natural Hazards. Kathmandu: ICIMOD.
Deoja, B.; Dhital, M.R.; Thapa, B.; and Wagner, A. (eds), 1991. Mountain Risk
Engineering Handbook (2 volumes and an awareness document). Kathmandu: ICIMOD
Chalise, S.R.; Shrestha, M.L.; Nayaju, R.P., 1995. Rainfall as the Primary Indicator of
Water Induced Disaster in Nepal. 'Paper presented at the `International Seminar on Water
Induced Disaster'. Kathmandu, Nepal, March 2024, 1995.
HMG, 1995. The National Action Plan for the IDNDR. Kathmandu: HMG/Nepal.
Ives, J., 1986. Glacial Lake Outburst Floods and Risk Engineering in the Himalaya.
Occasional Paper No. 5. Kathmandu: ICIMOD
Li Tianchi, 1996. Landslide Hazard Mapping and Management in China. Kathmandu: ICIMOD.
Malik, M.H. and Farooq, S., 1996. Landslide Hazard Management and Control in Pakistan.
Kathmandu: ICIMOD.
Thakur, V., 1996. Landslide Hazard Management and Control in India. Kathmandu: ICIMOD.
UNDP/UNCHS (Habitat), 1994. "The Development of Alternative Building Materials and
Technologies for Nepal." Prepared by Beca Worley International Consultants (New
Zealand) in association with TAEC Consult (P) (Nepal); SILT Consultants (P) (Nepal), and
Urban Regional Research (USA).
Upreti, B.N., 1995. "Reducing Natural Hazards in Nepal: Need for Action."
Paper presented at a Seminar organised by the Nepal Geological Society, Kathmandu.
Upreti, B.N. and Dhital, M.R., 1996. Landslide Hazard Management and Control in Nepal.
Kathmandu: ICIMOD.
Water Induced Disaster Prevention Technical Centre, 1995. Report on a Debris Flow
Disaster at Bagarchhap, Manang District. Kathmandu: WIDPTC.
For more information, contact:
B.N. Upreti
Head of Geology
Tri-Chandra Campus
Tribhuvan University
Kirtipur, Nepal |
and |
Greta Rana
Senior Editor
ICIMOD
Jawalakhel, Nepal
e-mail: grana@icimod.org.np |
