AN OVERVIEW ON FORECASTING ASSESSING AND MITIGATING AVALANCHE
RISKS
Sandeep Sushil Srivastav1 and Dr Shri Ram2
Department of Civil Engineering.
Madan Mohan Malviya Uniiversity of Technology, Gorakhpur, India
E-mail:,1sandeepsushilsrivastava@gmail.com, 2src_gkp@rediffmail.com
ABSTRACT
Avalanche events depend not only on the
accumulated snow cover over the mountain
slope but also the subsequent snowfall intensity.
Spatial snow holding capacity of mountain
slopes and the probability of initiation of snow
avalanches over parts of Beas River valley,
Uttarakhand, India, was attempted using maps
showing terrain characteristics and satellite
images along with meteorological information.
Contributory factors in retaining the snowfall,
snow fall variation and snow pack
characteristics were ranked and assigned weight
age towards the avalanche initiation based on
the reported events in the region. Spatial
distribution of Snow Accumulation Zone (SAZ),
Snow fall Area (SFA) and Snow Pack Stability
(SPS) assessment criteria was developed.
Mountain forests play a crucial role in
avalanche mitigation by hindering avalanche
formation. Nevertheless, due to the complex
interactions between ecological conditions,
terrain,
snowpack
and
meteorological
parameters the protective effect of forests may
be reduced. Channels, it is still the forecasters
ultimate responsibility to check and modify the
computer's prediction. This new way of
avalanche forecasting, which we call 'computer
aided avalanche forecasting'. The goal was to
review past and current avalanche research,
education, and forecasting efforts around the
world, and based on these to provide
recommendations and a roadmap for future
efforts. In this paper, we present future key
directions and priorities in the areas of
research, education and forecasting. Our future
research topics are location unique, but the
results of which have worldwide implications.
KEYWORDS:
Forecasting,
Mitigation,
Avalanche risks.
INTRODUCTION
Avalanches are one of the major geological
hazards in the Himalayan-Hindukush belt of
South Asia causing enormous damage to life
and property particularly in areas close to
the snowline. On a global scale, the South
Asian region is one of the hot spots of
avalanches and associated slope failure
phenomena. Masses of snow-and ice crystals
admixed with air decending from mountain
top at very high speed and flowing like
rivers of snow and ice blocks in the valley
below are known as avalanche. A avalanche
is defined as a fast, down-slope moving
mass of snow along-with associated debris
which is capable of damaging most
manmade structures such as highways,
railways, houses etc.
FACTORS USED FOR CLASSIFICATION OF AVALANCHES
Classification Factor Classification efinition
CLASSIFICATION
CLASSIFICATION
DEFINITION
FACTOR
FACTOR
Avalanche Consist of snow
Loose snow avalanche
crystals of snow admixed with
air, the loose in aggregate set in
motion by snow-storms.
Type of occurrence
Avalanches that start to move
Slab avalanche
suddenly over wide areas,
normally large in scale.
Avalanches that contain no
Dry snow avalanche
water.
Type of snow
Avalanches that contain water.
Wet snow avalanche
Surface layer avalanche
Slip surface exists
within the snow cover
Surface layer avalanche
Full- depth avalanche
Slip surface occurs on
the ground surface
CHARACTERISTIC FEATURE OF
AVALANCHE MOVEMENT
Powder
This type avalanche often reaches a depth of several tens of meters, taking
avalanche
the form of snow powder moving at a high speed. These most often occur
during snowfalls at low temperature.
Flow avalanche
This type of avalanche appears to move as a flow of water over the snow
surface. These are seen as full- depth avalanche occurring when atmospheric
temperature increases.
Mixed
avalanche
Powder type and flow avalanches occurring in combination. This type
avalanche can occur quickly when large quantity to snow falls over unstable
snow cover.
REVIEW OF LITERATURE
Michaela Teich et al., (2011-12). They have
given their review about the Forecasting
forest avalanches. They studied about snow
and weather situation as they characterized
winter 2011/12 by several large snowfall
events in December and January which
resulted in a well above average snow depth
i.e. about 1.5 to 2 times the normal snow
depth in most part of Swiss alps. In mid
February, the snow pack structure in open
unfrosted terrain generally consisted of a
well consolidated middle and lower part
without significant weak layers, more snow
and snowpack parameters (in addition to
snow depth and new snow height) could be
implemented into the model to increase its
applicability for forest avalanche forecasting
Krister Kristensen et al., (2011-12).They
studied about the “Avalanche forecasting
and risks mitigation for specific objects at
risks” They assessed Objects and individuals
can be exposed to different levels of
avalanche hazard there is a need in Norway
for both regional and local avalanche
forecasting. It would be useful to discuss
procedures on how to communicate danger
locally and the relationship between regional
and local forecast.
A.Ganju and A.P.dimri (2002). They studied
about Prevention and Mitigation of
Avalanche Disasters in Western Himalayan
Region. In this paper they discuses the cause
of avalanches, the magnitude of their
destruction power and the techniques
followed in India by the Snow and
Avalanche Study Establishment (SASE), a
DRDO Laboratory, for mitigating avalanche
disasters in Western Himalayan Region for
the defense forces. The authors suggest that
an integrated plan for mitigating the
avalanche disasters should be set up at
national level, involving defense forces and
state governments. There is also a
requirement for improving the accuracy of
avalanche forecasting by developing
avalanche-forecasting models for different
areas. If models are to produce accurate
results, there is a need to enlarge the
observatory network (Automatic Weather
Station based). For projected weather
conditions there is a requirement to develop
a Quantitative Precipitation Forecast (QPF)
model. And finally, there should be some
national policy for creating well equipped
and trained Avalanche Safety and Rescue
Organization
Omer Murat Yavas et al., (2009). They
studied about Avalanche Disasters in Turky.
Their study
For decreasing the losses and damages
because of snow avalanches, using of
avalanche risk
Map which creates from avalanche maps is
best method. Par avalanche structures will
project according to these maps. This will
provide financial benefit. Maps are used in
selection of resettlement areas because of
natural disasters. This will provide safe
settlement against avalanche.
Jurg Schweizer et al., (2009).They studied
about On forecasting large and infrequent
snow avalanches. They have analysed the
avalanche activity for the well documented
Salezertobel avalanche path near Davos
(Switzerland) for the period 1950–1951 to
2007–2008. The return period for an
avalanche to the road level (now protected
by a shed) was 5 years. For the analysis,
they used snow and weather data from two
locations, one representative for the starting
zone , the other for the run-out zone. The
data collected at the valley bottom were as
useful as the data from the elevation of the
starting zone. Forecasting based on data
from
Weissfluhjoch—though
highly
correlated with large avalanche events —
caused more false alarms than when the data
from Davos were used. Though the
conditions at the elevation of the starting
zone are undoubtedly better captured with
automatic stations at this elevation, the data
might not be appropriate for forecasting
extreme events due to their inherent low
predictability.
G.B.Crosta et al., (2006). They studied
about Forecasting hazard scenarios and
implications for the evaluation of
countermeasure efficiency for large debris
avalanches. They assessed the design criteria
for passive counter measures are lacking,
and very often the working conditions are
also unknown. Regardless of the
uncertainties and variations, the most
important parameters necessary to the
reasonable design for all mitigation
structures are those of a kinematic type are
debris moving velocity, maximum discharge
or hydrograph and volume. Also, designs of
mitigation structures are very site specific
and must include both the character of the
subject event, and the runout path and
deposition zone. One of the important tools
for mitigation structure evaluation is a
mobility analysis of the entire runout
process, which may not be used to estimate
the hazard zones in potential debris released
areas and the dynamic parameters during
runout.
Markus Eckerstofer et al., (2013).They
studied about Avalanche research, education
and forecasting in Svalbard, Norway – A
roadmap provided by an expert workshop in
Longyearbyen, April 2013.
Using the
research efforts undertaken to date as
starting point, the three interrelated topics
of, avalanche research, education and
forecasting were discussed during the expert
workshop. This was complimented with
several field trips into the local surroundings
to help the participants familiarize
themselves with the local issues and snow
and avalanche setting Future avalanche
research, avalanche education, avalanche
forecasting to improve climate and snow
observations
K.Srinivasan et al., (2005). They studied
about Usefulness of mesoscale weather
forecast
for
avalanche
forecasting.
Qualitative and site-wise prediction of
avalanches as well as integrated avalanche
forecast models require precise weather
forecast. Ideally speaking, the numerical
forecast of the following weather elements
up to 7 km altitude at least 24 h in advance,
preferably 3 days in advance, is required for
the purpose of avalanche forecasting or for
the use of avalanche forecast models.
Peter Carter et al., (2004). They studied
about “Evaluating the stuff block ant tilt
board snowpack stability tests as snow
avalanche forecasting tools”. Result
indicates during the winter there were eight
major avalanche cycles with each cycle
producing numerous natural avalanches
outside the ski area.
MAJOR CAUSES OF SNOW AVALANCHES
ITEM
DESCRIPTION
Topographic factors
Prime factor
Vegetation factors
Weather factors
Exciting factor
Other factors
AVALANCHES PRONE AREAS IN
INDIA
The snowbound belt of Western and Central
Himalaya and to some extent in Eastern
Himalaya known as avalanche prone area.
Indian Himalaya stretches from east to west
for about 2500 km across 72°E to 96°E long.
And 26°N to 37°N lat. From the main
Himalayan belt, the main mountain system
is divided into three principle zones. These
are the Great Himalaya, Lesser Himalaya
and the Outer Himalaya. The Himalaya have
about 43,000 km2 of permanent ice bound
area. The Himalayas are well known for the
occurrence of snow avalanches particularly
Western Himalayas I .e. the snowy regions
of Jammu and Kashmir, Himachal Pradesh,
Sikkim and Uttarakhand
Uttarakhand - Parts of Tehri Garhwal and
Chamoli districts are vulnerable areas.
Jammu and Kashmir - Higher reaches of
Kashmir and Gurez valleys, Kargil and
Ladakh and some of the major roads.
FACTOR
• Inclination of slope
• Shape of slope
• Orientation of slope
• Vegetation cover and height
of trees
• Vegetation cover and its thickness
• Depth of snow cover
• Wind velocity
• Atmospheric and snow temperatures
• Increase in weight of snow
cover because of snow
• Dropping from cornices or
snow covers
Himachal Pradesh - Chamba, Kullu- Spiti
and Kinnaur vulnerable areas.
AVALANCHE ZONES
Red Zone - The most dangerous zone where
snow avalanches are most frequent and have
an impact pressure of more than 3 tonnes per
square metre.
Blue Zone - Where the avalanche force is
less than 3 tonnes per square metre and
where living and other activities may be
permitted with connection of safe design but
such areas may have to be vacated on
warning.
Yellow Zone - Where snow avalanche occur
only occasionally.
AVALANCHES OCCURRENCE
When the weight of the snowpack exceeds
the shear strength within it and the mass of
snow slides down slope. When a large slab
of snow breaks free from the layers beneath
and starts moving downward with a
relatively high velocity – it accounts for
around 90 percent of avalanche-related
fatalities. When a snowpack becomes
saturated with water and tends to spread out
from a point.
TYPES OF DAMAGE
Damage to roads caused by avalanches the
scale of damage can differ depending on the
scale and type of avalanche traffic blocked
by snow deposited on road surface
avalanches damage road structures, such as
retaining walls, overturned as well
structures damaged by an avalanche during
construction of roads occur most frequently.
AVALANCHE INCIDENTS IN INDIA
DURING PAST YEARS
Catastrophic snowstorm and avalanches
played havoc in the Himalayan State of
Uttarakhand, a snow avalanche triggered
from the Gomukh glacier area caused the
death of one person and injured nine persons
on 3 June 2008. Among the injured, one
tourist was from the United Kingdom and
three were from the United States.The area
attracts thousands of pilgrims and tourists
every year who visit the Gomukh glacier
and the shrine at Gangotri. In another
incident on 24 June 2008, an avalanche
triggered by heavy precipitation near the
Hemkund Sahib shrine in Rudraprayag
district of Uttrakhand killed six pilgrims on
the spot and injured more than 40 people. In
another event on 21 September 2008, 3
persons were killed in a snow storm and
another 37 persons were rescued from
Kalindi-Badrinath track in the Garhwal
Himalaya, Uttarakhand.
In Himachal Pradesh on 22 September 2008,
an avalanche triggered from the snow
covered peaks wrecked havoc along the
Manali-Leh Highway in Mandi district by
killing seven persons and twelve persons
went missing. In Jammu and Kashmir
during the first half of February 2008. More
than 30 persons were killed in avalanches
during 8-9 February 2008 particularly in
Doda, Ramban and Kishtwar districts of the
state, village of Ramban district, six persons
of a family were buried when an avalanche
struck their house. In another fatal incident
in Jammu and Kashmir on 18 November
2008, six army personnel were killed.
INDIAN INITIATIVES TO MITIGATE
AVALANCHE RISKS
In India, the Snow and Avalanche Study
Establishment (SASE), is an unique agency
dedicated to the study of avalanche related
hazards and their mitigation. It was set up in
1969 near Manali to combat the hazards of
snow and avalanches. SASE was initially
assigned the task of studying snow and
avalanche problems along certain mountain
highways in the snowbound belt of Indian
Himalayas. This was subsequently extended
to encompass various other roads. SASE’s
major activities and achievements include
Avalanche mapping, in which a number of
highways and lateral road axes in Jammu
and Kashmir, Himachal Pradesh and
Uttarakhand have been studied for
identification and registration of snow
avalanche paths, snow drift deposition and
ice formation sites, frequency and severity
of avalanche activity, and the extent up to
which highways are affected. SASE’s
produced an avalanche atlas with details
such as frequency of occurrence of
avalanches, magnitude of damage, proposed
control measures, etc. Automatic Weather
Stations (AWS) network has been
established in high altitude regions of
Jammu and Kashmir, Himachal Pradesh and
Uttarakhand for acquiring uninterrupted
snow and meteorological data. The data
from all the stations are received at RDC
SASE.An observatory network has been set
up for acquiring snow and meteorological
data which aids in avalanche forecasting,
also high altitude manned observatories
have been set up in Jammu and Kashmir,
Himachal Pradesh and Uttarakhand.
Avalanche forecasting programmes have
been initiated which include issuing of
avalanche warning bulletins for generating
awareness amongst the users and reduce
casualty rates, snow bulletins for selected
regions of Jammu and Kashmir, Himachal
Pradesh and Uttarakhand are given to the
media and also broadcast on All India Radio
(AIR). Artificial triggering of avalanches by
different methods has been experimented
and the methodology for De-icing of roads
has been developed. Recent Initiatives
towards avalanche risk mitigation, a
Memorandum of Understanding (MoU) was
signed on 1 May 2008 by the Indian Space
Research Organisation (ISRO) with the
Snow and Avalanche Study Establishment
(SASE) of the Defence Research and
Development Organisation (DRDO) for the
installation of two Doppler Weather Radars
in the Himalayan region for climate studies.
The indigenously developed Doppler
Weather Radar (DWR) operate in the S band
and are capable of monitoring clouds,
precipitation systems and winds over large
areas of more than 400 km from the radar
location.
ASSESSMENT
OF
HAZARDOUS
SLOPES
Advise residents of avalanche risk areas
using published maps.
Afforestation programmes for areas where
there is risk of avalanches.
Trap avalanches by control measures.
Dispose avalanche potential snow packs by
artificial triggering.
Predict occurrence of avalanches through
stability analysis and issue warnings as and
when necessary.
Guide residents to emergency evacuation
shelters.
MITIGATION OF AVALANCHE
HAZARDS
Strategy
One way of coping with the hazard of
avalanche is to reduce their intensity and
destructiveness by raising barriers or such
engineering structures in their paths, or
diverting their course. The snow and
Avalanche Study Establishment roads has
achieved considerable success in forecasting
the occurrence of avalanche on strategic
roads. When stressed, the crystals of ice and
snow, characterized by microscopic
fractures, emit supersonic signals which can
be detected and monitored as warning
signals.
Pre-emptive artificial triggering
This experiment has been used for avalanche
of small size by repeatedly hurling explosive
projectiles on the snowy slopes, blowing off
the overhanging cornices and releasing
potential avalanche avalanches without
allowing them to grow to an unmanageable
size.
Avalanche – Preventing
In the upper part of the slope where
avalanches commonly develop and are
triggered, structures normal to the slope
direction are constructed. The retaining
structures in the upper part of the slope
prevent buildup of stresses in snow masses
in the formation zone and thus prevent
avalanche occurrence. Retaining walls of
steel and concrete help avert rupturing of
snow heels that give rise to slab avalanches.
Below the tree line the snow drift control
structures include snow bridges or snow
rakes of timber or aluminum, or steel tubes
and pre-stressed concrete, or snow nets of
wire or nylon ropes.
railroad project, questions often arise on the
forecasting of the danger to specific objects
at risk. highlights possible improvements of
the tested approach for forest avalanche
forecasting. To strengthen our assumptions,
further investigations of the snowpack in
forests and the comparison with its
development in open unforested terrain as
well as reanalyzing existing snow profiles
recorded in forests would be highly
valuable. Based on such investigations,
more snow and snowpack parameters (in
addition to snow depth and new snow
height) could be implemented into the model
to increase its applicability.
Avalanche ramps allow passage over
installations and buildings. Avalanche
wedges deflect the snow, break the speed of
descending masses of snow and ice and thus
provide protection to buildings and
installations. This is being done to protect
the temples of Badrinath. Underground
construction is the best measure against
avalanche chronically affected areas. The
Banihal tunnel on the jammu-srinagar
highway was constructed to avoid endemic
avalanches on the slope of Pir Panjal Range.
CONCLUSIONS
Extraordinary avalanche events result from
unusual snowpack’s, unusual storm events,
or both.. Avalanche activity was notable
throughout the region, and resulted in
considerable damage to buildings and
forests, disruption of recreational facilities
and transportation corridors, and several
fatalities. Damage and death tolls during a
similar event in the future might be much
higher since the mountain ranges of the
Himalaya are coming under increasing
development pressure, thereby increasing
the human exposure to avalanches.
DISCUSSION
Using the research efforts undertaken to date
as starting point, the three inter related
topics of, Avalanche research, education and
forecasting were discussed during the expert
workshop. This was complimented with
several field trips into the local surroundings
to help the participants familiarize
themselves with the local issues and snow
and avalanche setting during a highway or a
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