Majurmarg-60, Panipokhari, Maharajgunj,
Kathmandu, Nepal, e-mail:kpkaphle@gmail.com
Abstract
Geological and
hydro-meteorological hazards are common in all parts of Nepal. In many cases
both of them are interrelated and initiate each other to bring the disaster. Because
of the location of Nepal in the geo-dynamically very active Himalayan belts it
frequently suffers from these hazards and there is a considerable loss of about
865 lives every year (on average), huge loss of properties and damage of
infrastructures. Hazard when interact
with vulnerability it brings the disasters in the affected areas. Hazard
maps are very important for disaster management, land use planning,
infrastructure development planning, environment protection etc. Such maps
identify the risk areas so that precautionary measures against possible
disaster can be taken in advance. Preparation of hazard maps, their application
to identify different types of hazards and possible risk areas and take precautionary
measures to save the vulnerable people, public properties and infrastructures
are extremely important in disaster risk management and environment protection.
There is a need of good coordination and combined efforts of the government, NGOs, INGOs as well as bilateral and
multilateral agencies to deal with all types of disaster and save
the vulnerable people, infrastructures and protect the natural environment.
1. Introduction
It is believed that the Himalayan Mountain Belt
(Greater Himalaya) is the result of collision of the Indian plate with the Eurasian
(Tibetan) plate (Fig.1) in Tertiary time and
it was succeeded by the uplift of the Himalayas. Subduction of Indian plate under the Tibetan plate is still continued. The Nepal Himalaya occupies the
central part of 2500km long youngest and highest mountain belt in the earth (Fig.2). Because of its location in the Himalaya,
complex geology, rugged topography and continues geodynamic activities there in,
Nepal Himalaya as a whole is prone to different types of hazard. In the world scenario
Nepal is ranked in 11th position among 200 countries with respect to earthquake
risk and 30th in terms of flood risk. The residents of this region as a whole
are vulnerable to Earthquake. There are more than 3000 glacier lakes in the
Higher Himalayan regions of Nepal Nepal
Fig.1: Collision of the
Indian Plate with Tibetan Plate and formation of the Himalaya Fig.2: Location of Nepal
Himalaya
All types of hazards when interact with vulnerability bring the disasters
which disturb the normal life and social system, degrade the environments and
aggravate the poverty and ecosystem in the affected areas. In last 27 years
natural disasters have caused tremendous losses of lives and property in Nepal.
The disasters have brought about the average loss of about 6% of the annual
development expenditure of the government. Both the natural and anthropogenic
disasters are deteriorating the natural environment in Nepal
Nepal Himalaya can be divided into five distinct
morpho-geotectonic zones (Fig.3) separated by
major linear geological structures (Thrusts/ Faults). Each thrust/ fault forms the tectonic boundary line
between the two consecutive zones and control the basic frame work of the Himalaya . All of them dip towards north. MCT is the oldest thrust among them. MFT is
the youngest and most active ones. However, other thrusts are also contributing
in geodynamic activities and causes geogenic hazards like earthquake, landslide, debris flow, rock avalanche,
soil erosion, land subsidence, sinkholes and similarly Hydro-meteorological
hazards like many cases both of them are interrelated and initiate each other
to bring the disaster. Each zone is under risk of some hazards and they are
described in brief.
The Inner Himalaya (Tibetan Tethys) Zone
lies in the northern most part of the
Himalayan belt in between Tsangpo Suture Zone in the north and South Tibetan Detachment
Fault System (STDFS) in the south. The common geohazards in this zone are
earthquake, ice avalanche, windstorm and drought. The Higher Himalaya (HH) region lies in between STDFS in the north and
Main Central Thrust (MCT) in the south (Fig.3).
In this region the common geohazards are Glaciers and GLOF, Ice avalanche,
Earthquake and Debris flow. Similarly the
Lesser Himalayan (LH) zone
lies in between the MCT in the north and MBT in the south. This zone is prone to
natural hazards like Earthquake, Landslide, Flood, Debris flow, Soil erosion, Thunder/
wind storm, Hailstone etc. At places land subsidence in Kathmandu valley has already
started and sinkholes are common hazards in some parts of Pokhara. The Sub-Himalaya/
Siwalik Foot Hills (SH) lie in between MBT in the north and MFT in the
south. MFT is very active and can be traced at many places in Dharan, Sindhuli,
Butwal and Godabari (Kailali) area. Earthquake, Soil erosion, Landslide, Debris
flow, Rock block fall, Flood, fire, Epidemic are the main hazards that
frequently hit this area. The Terai Plain
(TP) area is the northern fringe of Indogangatic plain. It lies towards
south of the Siwalik foot hills and extend east to west throughout the country.
The possible common hazards in this area are the earthquake, flood, soil
erosion, river bank cutting/ collapse, cold & hot waves, fire, epidemic etc.
3. Common Hazards and Their Risk in Nepal
3.1 Earthquake
From
Microseismicity map of Nepal (Fig.4) one can
see very clearly that a number of earthquakes of small magnitude (<4), moderate
magnitude (4 to <6) and few with high magnitude (>6) had occurred in the
past. Similarly Earthquake Hazard map of Nepal Kathmandu
Valley
Fig.4: Microseismicity map of Nepal
Recent
studies carried out by different organizations and individuals have shown that
Kathmandu is ranked as one of the world's most vulnerable cities for an
earthquake disaster. DMG/NSC (2007); and JICA (2002) reported that if an
earthquake similar to that of 1934 hits the Kathmandu
valley, there will be a huge loss of lives and property. The Kathmandu Valley
Earthquake Risk Management Project (KVERMP, 1999) has predicted that an
earthquake similar to that of 1934 would cause 40,000 deaths and 95,000 serious
injuries from 600,000 to 900,000 residents of the Kathmandu
valley could be homeless and almost 60% of the infrastructures will be either
damaged (40%) or destroyed (20%). Many losses will bring by creeping disasters such
as fire, epidemic etc. after the earthquake.
Fig.5: Earthquake Hazard Map of Nepal
Table-1: Some major Historical
Earthquakes in Nepal
|
Year
|
Richter
scale
|
People
killed
|
Houses
destroyed
|
Remarks
|
|
1255AD
|
>8
|
No
proper records
|
No
proper records
|
No
proper records exist
|
|
1310BS
|
Big
earthquake
|
No
proper records
|
No
proper records
|
No
proper records exist
|
|
1373BS
|
"
|
No
proper records
|
No
proper records
|
No
proper records exist
|
|
1810AD
|
>8
|
No
proper records
|
No
proper records
|
Almost
30% people of KTM valley were affected
|
|
1833AD
|
7.8
|
No
record
|
4214
houses collapsed
|
KTM
valley highly affected
|
|
1866AD
|
>8
|
No
proper records
|
No
proper records
|
No
proper records available
|
|
1934AD
|
8.4
|
8519
|
80,890 houses collapsed and 207,248 damaged
|
Huge loss of lives, properties and damage of
infrastructures.
|
|
1966AD
|
6.5
- 7
|
24
|
>1300
houses collapsed
|
Hilly
districts of Far-western
|
|
1980AD
|
6.5
|
178 died and injured 391
|
40,000
houses damaged
|
Far-western
|
|
1988AD
|
6.6
|
721
died and 6553 injured
|
65,432,houses
collapsed 235,403 damaged
|
Houses
and physical structures collapsed
|
Source:
Earthquake Catalogue
Fig.6: Bhaktapur Durbar square, before
and after the 1934 earthquake.
3.2 Landslide and Debris Flow
Landslides
are the most common geogenic hazards that affect some parts of the country
every year. Topography, high angle slopes, fragile geology, deforestation, haphazard
road cuttings, improper cultivation practices on high angle sloppy lands in the
mountain region and high precipitation during monsoon time are the major causes
of soil erosion and landslides in Nepal (Fig.7
& 8). High intensity rainfall (cloud burst), earthquake etc.
contribute to trigger landslides. As a result loss of lives, damage/ blockage
of road, destruction of houses, and other infrastructures, cultivated land/
crops etc. take place. Some of the examples are
the occurrences of more than 2000 landslides in 7 districts of Central Nepal during 1993 landslide and flood disaster. Tribhuvan Highway was washed away at 20 places and 3
major concrete reinforced bridges on Agra Khola, Belkhu Khola and Malekhu Khola
along Prithivi Highway were collapsed. In this disaster 1336 people lost their
lives, 408,109 people of 72,091 families were affected and 32,765 houses were
collapsed and infrastructures of millions of Dollars were damaged (MOHA).
Fig.7: Jyotinagar/ Srawandanda Landslide in
Butwal, Rupandehi district (37 houses collapsed)
Fig.8: Laprak Landslide in Gorkha district (Source R.P,
Khanal, DMG) >500 houses and 2600 people on risk
Fig.9: Seti River
Bank/ Highway Bridge
Collapse, Pokhara Fig.10: Partial Filling of Phewa Lake
3.3 Flood
Flood
is also another most frequent hazard that is becoming an annual episode due to
heavy and prolong rain fall during monsoon season in Nepal. The low land areas
in Terai and some parts of mid valleys are frequently suffered from flood hazard.
It is because of poor land and water management system. Flooding also takes
place due to blockage of natural drainage by huge landslide and man made
structures like dam or bunds. Severe flood causes flood disaster and the extent
of damage of infrastructures and loss of properties and lives is hard to
predict. From the records of 1983 - 2009 it is clear that almost 35% of the
total death is due to flood and landslide (Disaster Review-2010). The huge
amount of sediments carried out by the rivers from the mountains during
landslide/ debris flow and deposited them in low lands or in lakes (Fig.10). Occasionally debris flow deposit blocks
the river as a result it changes the course and gets flooded large areas.
Squatter settlements along the river bank, old flood plains or terraces and at
the base of slope or on old landslide debris deposits are vulnerable to flood
and landslides. In many cities encroachment of river banks and flood plain areas
by the people and haphazard construction of houses and compound walls etc. have
narrowed down the stream course. As a result during heavy rain fall they
suffered from bank cutting and damage of bridge embankments and flooding on
either sides as a result damaging houses and infrastructures (e.g. in Bagmati,
Bishnumati, Tukucha and other streams in Kathmandu; Seti river in Pokhara; Sardu
Khola and Seuti Khola in Dharan; Tinau Khola in Butwal; Rapti Khola in Hetaunda
etc.). Settlements along the Seti River banks and Laltin Bazaar in Pokhara are
vulnerable to block fall due to bank collapse and flooding due to blockage of
river flow respectively. Because of river bank cutting and block fall the highway
bridge on Seti River
Fig.11: Koshi
River
3.4 Glacier Lake Outburst Flood (GLOF)
In
the last 100 years, because of global warming and consequently rapid melting of
glaciers has created a number of glacial lakes due to blocking the glaciers by
its terminal moraines and ice blocks in the Higher Himalayan region of Nepal.
There are more than 3000 glacial lakes, out of
which 27 are dangerous that can burst at any time. Their size and volume of
water are increasing year after year. Once the force of impounded water (glacier
lake, Fig.12) increased or some seismic
vibrations takes place due to earthquakes such blocked structure can be burst
and sudden release of voluminous water as glacier lake outburst flood causing damage
the infrastructures, public properties and loss of lives further downstream by
sudden flow of huge amount of debris and flood water mainly in the Lesser
Himalaya and Sub Himalaya region all along the river courses, their banks and
cultivated terraces. Only after the events of 1985 Dig Tso GLOF and its severe
effect like damage of Namche hydropower plant, agriculture lands etc. the Department
of Hydrology and Meteorology (DH&M) and ICIMOD had started their study on
most dangerous 6 glacier lakes and possible GLOF (Mool, P.K. et al 2001). Out
of these, Tsho Rolpa glacier in Koshi River and Thulagi glacier in Marshyangdi River
3.5 Land Subsidence and Sinkhole Hazard
Land
subsidence problem arises mainly in the urban areas like Kathmandu
and Pokhara. It is due to the weak ground consisting of loose soft sediment, over
extraction of the ground water and construction of heavy structures like multi
story buildings in Kathmandu Valley. Karstification is widespread in the form
of sinkholes, cavities, cavern and subsoil pinnacles in Pokhara valley, mainly in
the west of Seti River especially in old city area, dam site, Devid fall,
Gupteshor areas (Fig.13) and in Hengja area are
prone to sinkholes.
Fig13: A big sinkhole in Pokhara, Old
Gupteshor Fig.14: Thunderstorm and lightning
3.6 Windstorm and Thunder Storm
These
hazards are quite common in Nepal mainly during the month of May - July. Every
year some people lost their lives and loss properties by these disasters (Fig.14) in different parts of Nepal
3.7 Natural Radiation
Natural
radiations from radioactive bodies
are due to continues emanations of Gamma rays which can cause health hazard like
cancer, birth defects etc. in the long run. Such radioactive bodies are
recorded in different parts of Makwanpur (Fig.15A),
Sindhuli, Kathmandu , Baitadi (Fig.15B), and Darchula districts. Suitable precautionary
measures are warranted in such vulnerable areas.
Fig.15A: Radioactive body in
Tinbhangale, Makwanpur and Fig.15B in Gorang, Baitadi (Kaphle &
Khan 1989).
Beside
these above mentioned hazards there are few other common hazards that have
created disaster in different part of Nepal. They are Fire, Cold and hot waves
and Epidemic. Therefore, they are also briefly described here even if they are
not geology related hazards.
3.8 Fire
Fire
hazard arises mainly by human activities or sometime by thunder storm/
lightning or by any other ways like electric shut or gas leakage etc. Fire disasters
are particularly common during dry season mostly in Terai areas where roof of
the houses are made up of dry bamboo and hays. 109 persons lost their lives by
fire in 1989. Similar events in 1992 has destroyed 13,876 houses and 10,956
families were affected and 97 people lost their lives, and in 1994 about 4440
families were affected, 312 houses were caught by fire, 47 persons died and 74
persons were injured. In the last 25
years about 1300 people lost
their lives by fire disaster.
3.9 Epidemic
Epidemic
is neither a geo-hazard nor a hydro-meteorological hazard but it appears to be
the main killer in Nepal
Table-2: Historical records of loss of lives by
different disasters in last 23 years (1983 – 2005)
|
Hazard/ Disaster
|
Loss of lives
|
Millions USD
|
||||
|
Earthquake
|
727
|
|
||||
|
Landslide, Flood, GLOF
|
7084
|
|
||||
|
Windstorm & Thunder
|
636
|
|
||||
|
Avalanche
|
102
|
|
||||
|
Fire
|
1196
|
|
||||
|
Epidemic
|
12024
|
|
||||
|
Stampede
|
71
|
|
||||
|
Total
|
21,840
|
Billions of Dollars
|
Source: MOHA and DWIDP
Disaster Review
Explanation:1= Earthquake, 2 =
Flood, Landslide and GLOF, 3 = Wind storm/ Thunder, 4 = Avalanche, 5 = Fire, 6
= Epidemic, 7 = Stampede.
4. Geohazards and Environmental
Degradation in Nepal
Environment is our surroundings i.e. atmosphere,
hydrosphere, lithosphere and biosphere. Natural Environment is mainly
influenced by (a) Geology (Ground condition/ Rock and Soil types) (b)
Topography (c) Drainage (d) Climatic condition (e) Deforestation (f) Changes
in natural physical features (g) Unplanned infrastructure development works (h)
Haphazard urbanization and expansion of settlement areas (i) Improper locations
of industries and industrial areas (Fig.17, 18A,
19, 20) (j) Improper land use (k) Mismanagement of sewage drains and
solid waste (Fig18A,
18B, 21) (l) Over use of insecticide and chemical fertilizer (m) Ground/
water/ air pollution and (n) contamination of drinking water (Fig.22) etc. Natural
hazards like earthquake, soil erosion, landslide, debris flow, flood, GLOF,
volcanic eruptions, tsunami, snow melting, sea level rising, glacial lake
outburst floods, storms/ cyclone etc. bring the changes on the dynamic earth.
All these hazards along with day to day human activities aggravate the fragile
eco-system in the affected urban or rural areas and degrade the natural environment.
Human activities interact with nature in every region and natural dynamics of
the earth bring the natural changes in the earth. There is ever increasing of
population pressure in an alarming rate in most of the fast growing/ developing
urban areas like in Kathmandu, Pokhara, Butwal, Bhairahawa, Hetaunda, Dharan,
Janakpur, Biratnagar, Nepalgunj, Surkhet, Dhangadhi etc.
Fig.17: Air pollution from Dabar
Nepal and Hetaunda cement industries in Hetaunda.
Fig.18A:
Haphazard disposal of decayed organic materials and chemicals from a Leather
factory Fig.18B: Disposal of solid waste by the sides of road in Biratnagar
Fig.19:
Stone crushing Plants close to Highway, near Thankot, Kathmandu and Fig.20: Brick
kilns in the
middle
of settlement a source of air pollution causes of health hazard.
High
population growth rate and migration of people from rural areas to urban areas
in search of jobs, business, education, health, safety, and other opportunities
for livelihood there has been uncontrolled expansion of urban areas without any
consideration of the geological and environmental aspects. All these natural
and human induced hazards are helping to induce disaster and environmental
degradation that directly affecting the people and their livelihood.
FIg.21: Trees are dying due to haphazard
disposal of Solid waste in the middle of the Forest
in
Bharatpur/ Narayanghat
Municipality
|
5. Effects of Global Warming and Climate Change
Global
warming is a world wide problem. Due to global warming the climate is changing
year after year. As a result snowline in the high snow capped mountain is going
up, snow in the mountain is melting at fast rate, the number of glaciers and
their size are decreasing/ receding, as a consequence the number and size of
the glacier lakes are increasing. One of the example is about sixty years ago
there was no glacial lake in Imja glacier but now there appears a huge glacial
lake (Fig.23) which is the result of global
warming and snow melting. This glacier can burst at any time and bring GLOF
disaster.
Fig.23: Melting
of Imja Glacier and Development of
Glacier Lakes due to Global warming (Source ICIMOD)
6. Disaster
Management System in Nepal
6.1 Disaster Management
Disaster
management is the effective management of available resources and their proper
utilization for the pre-disaster preparedness and post-disaster rescue, relief
operation for the benefit of the disaster victims. Nepal
has accumulated considerable experiences in disaster management after the 1988 earthquake
in eastern Nepal and
landslide and flood of 1993 in Central Nepal . Both
of them were related to the post disaster rescue and relief operations. For
pre-disaster preparedness activities like preparation of hazard maps, follow
building code during construction, retrofitting of schools, hospital and public
buildings, special training to 12,000 police force and some military personnel
as well as civil servants, organizing public awareness programs, development of
warning system, proper storage of relief materials, alert of rescue groups, studies
and research on various types of natural hazards and anthropogenic hazards at
government and other non government agencies/ institutions are putting
considerable efforts on disaster management in Nepal. Now the focus is a bit
diverted from post disaster to pre-disaster preparedness. Out of 75 districts
20 districts are selected as highly disaster prone districts on the basis of
total disaster factors (i.e. high casualties and affected families in
2005/DWIDP-2005). Nepal Red Cross Society with coordination with government
organizations and international agencies is doing excellent work in this
aspect.
Natural
disasters cannot be stopped and they are not yet amendable to modification or
prevention. However, their impacts can be reduced significantly with the help
of proper methods of disaster management focusing on pre-disaster preparedness
activities. This was the central message of IDNDR declared by the UN for 1990 –
1999 AD. Disaster Management Strategy includes the whole cycle of disaster
management, starting from preparedness, mitigation, rescue, relief and
reconstruction to rehabilitation. Public awareness raising by training,
workshops, organizing earthquake safety day, rehearsal and drill etc. and
arrangements of early warning system are the part of preparedness. Government
has understood the importance of contingency planning for disaster management.
Exercises are going on for contingency planning for different scenario in
emergency situation. The government is aware of various types of disaster in
the country. To meet the challenges National Action Plan for disaster management
was prepared in 1996 which has been updated in 2005. A
"Comprehensive Data Base (Basic information) on Natural Disaster
Management Capabilities in Nepal Nepal
6.2 Organization Structure
Natural
Calamity Relief Act-1982 (amended in 1989 and 1992) has constituted an
organizational structure through which rescue, relief, rehabilitation and
resettlement programs are being carried out. In Nepal
7. Conclusion and Recommendation
In
Nepal among the natural hazards geogenic and climatological hazards are the
major ones which can bring the disaster at any time. Therefore, the disaster risk
management plan must equally focus on pre-disaster activities as the post
disaster activities to save the vulnerable people and infrastructures. Hazards
like earthquake, landslide, debris flow, flood, land subsidence, sinkholes etc.
should be treated as important parameters during planning, designing and
construction phase of the infrastructures, buildings etc.
Department
of Mines and Geology is regularly publishing geological maps and landslide
hazard zonation maps of different parts of Nepal; Engineering and Environmental
geological map of fast growing major cities of Nepal; and Microseismicity map
and Seismic hazard maps of Nepal. But similar flood hazard maps, GLOF hazard
maps, radiation hazard maps etc. are still lacking. All these maps are very
important for infrastructure development planning, hazard mitigation, disaster risk
management, environmental protection etc.
Government
should prepare an effective comprehensive management plan for disaster
preparedness. National Action Plan must be implemented by different concerning
government agencies with close cooperation of UN agencies, donors and NGOs just
to make easy to manage the disaster.
The
government, NGOs, INGOs as well as bilateral and multilateral agencies have least
coordination and most of them are even dealing with disaster in isolation.
Therefore, there is an immediate need of coordination among all these partners
and related organizations. Only then the objective of disaster management could
be fulfilled. Local people and committees are the first victims of natural
disaster and also the first respondents. Without their participation, disaster
cannot be well managed.
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