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Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
Geotechnical Measures for Uttarakhand Flash Flood-2013, India
C. Ghosh1 and I. Pal2
1National Institute of Disaster management, New Delhi, India
Email: cghosh24@gmail.com
2Disaster Preparedness, Mitigation and Management (DPMM), Asian Institute of Technology, Thailand
E-mail: indrajit-pal@ait.asia
ABSTRACT: Many “Run of the River” projects in the North West part of Himalaya have been frequented by “Cloud Burst” induced flash
flood in since 2009, which is primarily attributed to climate variability and land use pattern changes due to unregulated developmental
perspectives against the rising demand of tourist related establishments. Given the ageing population of vulnerable constructions along the
hilly terrains, safety issues require more attention in the form of technical auditing cum inspections, routine monitoring, emergency drills,
surveillance systems, and regularly updated emergency action plans. Added to this accelerated events of “cloud burst” induced flash flood in
the hilly region has opened up Dam safety issues, which are rather debated in the court of law for which geo-professional intervention are to
be looked into. This paper explains the climatic and other geo-morphological changes that might have caused Uttarakhand Flash Flood-2013.
Damages to the geotechnical structures in the form of excessive erosion, landslides, siltation of catchment area of several Dams in
Uttarakhand state of India are described along with some illustration of landslides mitigation by simple bio-engineering solution as one the
means of reconstruction measures across the state.
KEYWORDS: Climate change, Landslides, Cloud burst, Retaining walls, Bio-engineering, Vetiver grass, Soil nailing, Geocell
1. INTRODUCTION
The 2400km long Himalayan arc in the northern territory of India is
the home of vigorous seismo-tectonic activities and also subjected to
weather imbued hydro-geological-hazards that cause avalanches,
landslides and flash floods. Landslides and slope instability
problems are now being noticed in numerous Himalayan towns.
Natural drainage often gets blocked or obstructed by human activity
and surrounding hillsides get denuded because of increased human
pressure. According to the Intergovernmental Panel on Climate
Change scenarios, it is very likely that heavy precipitation will
become more frequent and it’s likely that future events will become
more intense and localised. The Uttarakhand state in India is one of
the 11 states facing mostly rainfall induced landslides and also
affected with earthquakes (Fig.1). The problems are mounting up
not merely due to the steep slopes, but because of the poor
stabilisation of the slopes and absence of geotechnical and
geological measures in the road constructions. Moreover, growing
dimensions of human settlement and the climatic variability as
notably found in the last one decade or so, have been causing
extensive flash flood induced damages and loss to the establishment
along the river terrains. As on date cloud bursts, flash floods,
landslides added with many ongoing hydropower projects in this
state, each project entailing dam, tunnels that need to be blasted
through, the roads, townships and deforestation, the distress and
damage potential goes up multi fold, particularly when there are no
credible environment of social impact assessments at project or
basin level (SANDRP). Systematic studies on the carrying capacity
of reservoir dam and undefined means and methodologies towards
credible compliance mechanisms to ICOLD standards are some of
the important issues to be discussed in the paper.
According to ICOLD, there have been about 200 notable reservoir
failures in 20th century in the world so far. Realizing the importance
of dam safety, many countries in the world have initiated action to
review the safety of dams in their countries. The review conducted
by US Army Crops of Engineers has revealed that out of 8819
review inspection completed, 2925 dams were evaluated as unsafe.
Of the various causes, inadequate spillway capacity was the primary
deficiency found in 81% of the unsafe dams. The height of new
dams and the volume of new reservoirs are increasing, while older
dams are approaching an age at which material deterioration and
decreasing operational reliability may dictate some repair and
upgrading. Certainly, both the growing dimensions of new dams and
the aging of older dams suggest a somewhat more rigid approach to
safety aspects. Given the ageing population of dams, safety issues
require more attention in the form of inspections, routine
monitoring, evaluations, surveillance systems, and regularly updated
emergency action plans. It is also important to update dams to
contemporary standards, especially regarding spillway capacity and
resistance to earthquakes.
Among all disasters riverine flooding is the most common of all
environmental hazards and it regularly claims over 20,000 lives per
year and adversely affects around 75 million people worldwide
(Smith et al., 1996). The reason lies in the widespread geographical
and geomorphological distribution of the tracks of rivers and
floodplains and low-lying coasts, together with their longstanding
attractions for human settlement (Ologunorisa and Abawua, 2005).
Death and destruction due to flooding continue to be too common
phenomena throughout the world today, affecting millions of people
annually. Floods cause about one third of all deaths, one third of all
injuries and one third of all damage from natural disasters
(Askew,1999). India has to face loss of life and damage to property
due to severe floods during the monsoons of 1955, 1971, 1973,
1977, 1978, 1980, 1984, 1988, 1989, 1998, 2001, 2004, and there
after urban floods in major cities of India are taking place almost
every year.
National Mission of Sustainable Himalayas, one of the nine
missions under National Action Plan on Climate Change, had made
a recommendation for protection of areas around the four pilgrimage
sites of Gangotri, Yamunotri, Kedarnath and Badrinath (Figure 1)
by creation of spiritual and ecological buffer zones around pilgrim
places in the ecologically-sensitive region. The mission noted that
construction of roads should be prohibited beyond at least 10 kms
from protected pilgrim sites. In order to reduce the damage impact,
Figure 1: Flash flood induced damages in Uttarakhand where
massive reconstruction work is under way
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
national parks and sanctuaries, can be maintained as special areas,
where there would be minimal human interference. It is therefore
highly important to strictly regulate developmental initiatives in
close vicinity of streams and rivers. Appropriate legislative
interventions would be required for formulating a policy in this
regard and firm executive action in accordance with letter and spirit
of this policy would be required to ensure compliance of the same.
2. CLOUD BURSTS INDUCED FLASH FLOODS
A cloudburst is an extreme weather event often associated with
climate variability across the globe, sometimes with hailstorm and
thunder, which normally lasts no longer than a few hours but is
capable of creating flood conditions. Colloquially, the term
cloudburst may be used to describe any sudden heavy, brief, and
usually unforecastable rainfall over a very specific area or typically
in the mountainous areas in India. Meteorologists say the
precipitation rate equal to or greater than 100 mm per hour is a
cloudburst. These events are often reported when there is a shift of
hot air from the ground up towards clouds which carry a large
amount of rain drops. The temperature difference eventually causes
the break, leading to the sudden discharge of water. The associated
convective cloud can extend up to a height of 15 km above the
ground. During a cloudburst, more than 20 mm of rain may fall in a
few minutes. In such high amount of intense rainfall in the hilly
areas of Uttarakhand state of India in June 2013, the country faced
severe shock and devastation due to flash flood.
There are a number of global instances of cloudburst. In 1906
Guinea (Virginia in USA) received 234,95 mm of rainfall for 40
min, in 1916 Plumb Point (Jamaica) experienced 198,12 mm of
rainfall for 15 min, Foc-Foc (La Reunion) in 1966 mm of rainfall for
13 hours, Ganges Delta (India) experienced 2,329 mm of rainfall for
20 hours in 1966, in 2010 Leh-Ladakh (India) received 250 mm of
rainfall for 1 hour and in 2010 Pashan (Pune, India) received 182
mm for 1.5 hours. Figure 2 shows the cloudburst in Himachal
Pradesh lying in the West side of Uttarakhand state in August 2015,
killing 4 people. On July 1, 2016, 30 people are killed and 15
missing due to cloudburst in the Pithoragarh and Chamoli districts
of Uttarakhand that measured 100mm of rain fall in 2 hrs.
Figure 2: Flooded Dharampur market and bus station after a
cloudburst in Mandi district, Himachal Pradesh in August 2015
(Photo: The Indian Express)
There are numerous examples in the past when flash floods in the
Himalaya have been responsible for causing land slip and washed
away village, bridge, roads disrupt communication for days (Dhar et
al., 1975). In September 1880, due to intense fall of rain in the
Garhwal-Kumaon hills, landslips and flash floods destroyed
numerous villages. Same kind of incident reported in Darjeeling and
Jalpaiguri district in June 1950. In July 1963, a portion of Pahelgam
town and Kashmir washed away by sudden swift rising of nearby
river. A major incident also took place in July 1970 in Alkananda
valley in the Garhwal Himalaya. In recent past Uttarkashi, a district
of Uttarakhand suddenly waterlogged due to flash flood caused by
cloudburst. The district also faced the heavy flood in 1978, 1997 and
1998, mass landslide in Varunawat hill in 2003, 2007 and 2007, in
Bhatwari village in 2011 (Onagh et al., 2012).
Flash floods are characterized by sudden rise and recession of flow
of small volume and high discharge, which causes damages because
of suddenness. It generally takes place in hilly region where the bed
slope is very steep (Pal et.al, 2014). Flash flooding occurs when
precipitation falls too quickly on saturated soil or dry soil that has
poor absorption ability. The runoff collects in low-lying areas and
rapidly flows downhill. Flash floods most often occur in normally
dry areas that have recently received precipitation, but may be seen
anywhere downstream from the source of the precipitation, even
many miles from the source. Among all other factors cloudburst is
one of the causes of flash floods in hilly areas. Flash floods have
high velocities and tremendous erosive forces, and only extremely
solid structures can withstand their destructive force. Rivers flowing
beyond its capacity could turn into a deluge if there is a cloudburst.
Such occurrences can also result in massive erosion of land, leading
to landslides and destruction of roads and national highways.
The damage potential of flash floods is confined to the direct
neighbourhood of the river (Figure 3), where the total damage
usually is not very extensive in spite of the high flow velocity. The
individual damage to structures or persons in such floods is very
high. In recent times, flash floods have caused large losses of life
only of people unfamiliar with the potential hazard, such as tourists,
who camp in the mountain canyons. In some areas, flash floods can
be avoided to some extent by flood control reservoirs (Plate, 2002).
Figure 3: Human settlements affected by flash flood in state of
Uttarakhand in June 2013, (a) Destruction of tourism infrastructure
built over river bed (b) Buildings in steep hill slope in danger due to
flash flood induced river bank erosion
(a)
(b)
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
3. UTTARAKHAND FLASH FLOOD-2013
The flash flood event of Uttarakhand (2013), which is the worst
disaster India faced after Indian Ocean Tsunami (2004) that killed
more than 5000 people is attributed to some of the following factors,
such as the uncontrolled tourism, illegal construction, unplanned and
ill planned construction around several pilgrimage sites, widening of
road without considering the geology and geomorphology, race of
hydel projects, blasting during roads and dam project, large number
of vehicular traffic infested with tourism. Absence of robust early
warning system makes the situation worse for the disaster response
managers of the state.
The Kedarnath shrine area (located at 3584 m above msl) (Figure
4a) faced two flash flood events, one starting around 8.15 pm on
June 16 and second at 6.55 am on June 17. The flood originated
from catchment that includes two mountain peaks: Kedarnath and
Kedarnath Dome (6831m elevation). Following torrential rains huge
boulders broke away from Kedar Dome and ruptured the
downstream Chorabari glacier (Figure 4e) and lake reservoir (Figure
4d), about 6 km upstream from the Kedarnath temple (Figure 4b)
along the Mandakini river (Figure 4c). This description seems to
suggest that this was also an event of GLOF (Glacial Lake Outburst
Flood) (www.sandrp.in). Figures 5a and 5b show the Indian Space
Research Organisation (ISRO) generated “Bhuvan” image,
describing the location of Kedarnath temple and it’s vulnerable
location, where Glacial Lake Outburst Flood (GLOF) have taken
place in addition to heavy rain fall in June-14-17, 2013.
Figure 4: Areal view of Kedarnath flash flood (2013) along with the
Chorabari Lake that was reported to burst out on 17th June 2013,
causing severe impact the Shrine complex
This event caused widespread damages and losses that have
contributed to decline in economy, tourism of Uttarakhand state of
India but it offers opportunities for advancement and growth. If
planned effectively, the recovery and reconstruction program could
offer opportunities to rebuild better, take advantage of economically
productive options. Reconstruction in Uttarakhand is to be taken up
as an opportunity to reduce the vulnerability of the state against
impending natural and manmade disasters by relocating settlements
in safer sites, introducing new building technologies for hilly
terrains, up-dating national building codes for disaster safe hill
areas, and by enhancing (through multiple strategies) disaster
preparedness at different levels. The reconstruction process shall
enable effective recovery support to flash flood impacted areas of
Uttarakhand in a unified and collaborative manner. It also focuses
on how best to restore, redevelop and revitalize the health, social,
economic, natural and environmental fabric of the community and
build a more resilient state.
Figure 5: Geo-spatial view of Flash flood area and its vulnerable
surroundings before the flash flood of June 17, 2013 (ISRO,
“Bhuvan” image)
Unprecedented destruction by the rainfall witnessed in Uttarakhand
state (Figure 6) was also attributed, by environmentalists, to
unscientific developmental activities undertaken in recent decades
contributing to high level of loss of property and lives (Kala, 2014).
Roads constructed in haphazard style, new resorts and hotels built
on fragile river banks and more than 70 hydroelectric projects in
the watersheds of the state led to a "disaster waiting to happen" as
termed by certain environmentalists (Shadbolt, 2013). The
environmental experts reported that the tunnels built and blasts
undertaken for the 70 hydro electric projects contributed to the
ecological imbalance in the state, with flows of river water restricted
and the streamside development activity contributing to a higher
number of landslides and more flooding.
Figure 6: Rescue scenario of flash affected people by Indian Army
and National Disaster Response Force deployed from June 18-27,
2013
(a)
(b)
(d)
(c)
(e)
(b)
(a)
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
4. DAMAGED HYDRO-ELECTRIC PROJECTS
A large number of hydropower projects (Figure 7) are coming up in
the state of Uttarakhand and some of them have suffered damage
due to the heavy rainfall induced flash flood in Uttarakhand and
nearby state of Himachal Pradesh. Some of the projects that have
suffered but unassessed damage include (SANDRP):
a. 520 MW under construction Tapovan Vishnugad Hydro
Electric Project (HEP) has suffered damaged by rains on June
16, 2013: While construction of diversion tunnel was
completed in April 2013, the same was washed away due to
heavy rains on June 16. It also caused serious damages in the
coffer dam of the project.
b. 400 MW Vishnuprayag HEP of JP Associates has suffered
serious, but as yet unassessed damage. As per MATU PR
(http://matuganga.blogspot.in/), the project has also been cause
of damage in Lambagad village,
c. 76 MW Phata Byung HEP of Lanco in Mandakini Valley in
Uttarakhand
d. 99 MW Singoli Bhatwari HEP of L&T in Mandakini Valley in
Uttarakhand and it was reported that the water level of the river
has gone up due to the silt dumped by dams.
e. Kali Ganga I, Kali Ganga II and Madhyamaheshwar HEP, all
in Mandakini Valley hit by mudslides
f. Assiganga I-IV projects on Assiganga river in Bhagirathi basin
in Uttarakhand
g. 65 MW Kashang HEP in Sutlej basin in Himachal Pradesh
h. 280MW Dhaulganga Project of NHPC in Pithoragarh district of
Uttarakhand and it was reported the power house and township
were submerged,
i. The 330 MW Srinagar project, a cause for downstream
destruction, has itself suffered massive damages on June 17,
2013, with breach of its protective embankment.
Figure 7: Some of the DAMs in Uttarakhand state that raises the
concern for maintaining appropriate E-flows in the rivers from the
Himalaya (Source: www.sandrp.in).
5. RECONSTRUCTION STRATEGY
Understanding the nature of disaster risks through hazard mapping
is of paramount importance for disaster risk management and
disaster resilient development planning, and requires a detailed
mapping and modeling exercise that includes climate change
projections. The key is really to understand the nature and
geographical distribution of risk and expected damages and to
incorporate these risks into planning, design, specifications of
infrastructure assets. Making these risk maps available to the public
in conjunction with training can improve widespread understanding
and is the first step towards planning a strong reconstruction
strategy.
The impact of post-disaster reconstruction on affected communities’
livelihoods and on their resilience to future disasters cannot be
analyzed immediately after the reconstruction period is over. Yet,
much research draws conclusions about the appropriateness of
various reconstruction approaches based on research carried out
during or shortly after their implementation. Significantly less
attention has been given to the long-term changes triggered by
reconstruction, and on whether the vulnerability of the concerned
communities to eventual future disasters is indeed mitigated.
The reconstruction strategy has to look into the nature of the high
vulnerability of mountain communities. Key activities that should be
undertaken include:
a. supporting sustainable agricultural, pasture and forestry
practices in mountain areas as a key element of disaster risk
reduction for both upland and lowland communities;
b. carrying out baseline vulnerability studies in mountain
community areas using gender analysis to ensure that disaster
risk reduction initiatives and emergency relief and rehabilitation
efforts target those most at risk;
c. increasing awareness and developing integrated strategies and
policies on disaster risk management at the national level;
d. integrating local environmental knowledge and community
memories in disaster risk reduction strategies.
e. increasing capacity building in all the elements of disaster risk
management, including preparedness, mitigation, response and
rehabilitation;
f. facilitating mountain communities access to resources through
several tools such as microcredit and banking, non-farm income
opportunities, as well as disaster mitigation strategies that offer
payments to mountain communities;
g. The reconstruction of Uttarakhand will have to be:
state-led and build upon local capacity with “build back
better” approach
comprehensive and integrated into the local economy and
livelihood regeneration
coordinated with the resources of the state and local
knowledge
sustained and accountable to:
o Roads and bridges that are reconstructed with new
technologies and knowhow
o Hill area infrastructure that are to be reconstructed and
upgraded
o Tourism Infrastructure and trekking routes
rehabilitated and reconstructed
o Bring forth improved capacity on disaster
preparedness and management.
o Ensure community participation in all aspects of
development, including those managed by outside
agencies and private contractors.
Realizing that heavy rain fall in Uttarakhand has caused extensive
damages along the river courses and the extent of devastation
became widespread due to landslides, the following sections present
some of the example of landslides stabilization measures by
innovative techniques, including bio-engineering solutions, followed
elsewhere in the country and abroad. Anthropogenic hazards play an
important role towards the risk factor of the region. Being an
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
important pilgrim destination, the region is facing high influx of
human and vehicles seasonally. Hence, high pressure on natural
resources creates an imbalance in ecology and environment. To
cater the huge seasonal pilgrim pressure; roads, bridges, hotels,
guest houses and other constructions related to hospitality and
support services throughout the year, certainly put pressure on the
natural equilibrium in terms of land use change, land degradation,
over exploitation of water resources etc.
The accelerated pace of erosion in this geo-dynamically sensitive
region coupled within supportably big growth in human and
livestock. (Pal, et. Al, 2014). Majority of the tributaries in the
watershed are seasonal in nature and major tributaries and small
rivers are perennial in nature. Therefore, the flow of water in the
river basins or throughout the watershed is not uniform or steady.
Due to the unpredictable water level rise during monsoon or during
heavy rainfall in the region, it is quite challenging to alert and
evacuate the people from the area of probable inundation. With the
limited data and documentation, Pal et. al (2014) attempted to
identify the potential hazard zone for the cloudburst and flash flood
hazard in the Asi Ganga River basin along with a part from the
Bhagirathi river basin. The identified vulnerable zone is useful for
the administrators and policy makers to prepare effective evacuation
plan and disaster management plan.
District administration and non-governmental organizations (Pant
and Pande, 2012) are taking few steps towards the mitigation and
preparedness for earthquake, landslides and forest fires by means of
imparting training to the officers and communities, distribution of
posters, brochures and pamphlets etc. Advance stock of food grains,
fuel and other essential commodities are done by the district
administration keeping in mind the previous experiences. Being
situated at the higher elevation, the district is infested with number
of watersheds.
6. INFRASTRUCTURE RESTORATION
All reconstruction projects must be cost-effective, be both
engineering and technically feasible, and meet environmental
planning and heritage preservation requirements of the nation.
Some of the important facts based on which entire reconstruction
program requires to be streamlined are:
a. Uttarakhand has a total area of 53,484 km², of which 93% is
mountainous and 64% of which is covered by forest. Most of the
northern part of the state is covered by high Himalayan peaks
and glaciers, while the lower foothills are densely forested.
Tectonically the state is very much susceptible to earthquake,
landslides, flash flood and forest fires. While taking up
reconstruction work the authority has to look into the hazard and
vulnerability profile of the state
b. Landslides, which are mostly happening along the non-
engineered hill roads or areas where drainage control measures
are not effective or in places where pre-existing sliding mass
gets aggravated due to rainwater infiltration; have been found
contributing more to soil erosion and siltation in river valleys.
How landslides can be prevented by advanced techniques
available in the country so that road communication remain
intact during emergency operation in the hill areas of
Uttarakhand
c. Deforestation is often blamed for landslides, but accountability
of the same has to be critically examined by expert group.
Possibility of innovative bio-engineering measures for slope
stabilization, while keeping in view of the conventional
practices followed in the hill area development so far.
d. While DAMs are needed to meet energy and economic
development requirements of the nation, building them in the
eco-sensitive areas of Uttarakhand is a construction-intensive
activity involving blasting, excavation, debris dumping,
movement of heavy machinery, diversion of forests and rivers.
Such activities cumulatively impact mountain ecology of
Uttarakhand and for this what kind of 3rd party assessment to be
initiated by State Govt and MoEF
e. The Uttarakhand state needs to come up with an action plan to
save its mountain ecosystem vis-à-vis “Char Dham” tourism
infrastructure networks, in which mountain people’s livelihood
is to be looked into. How newly established “Uttarakhand
Reconstruction Authority” shall regulate pilgrims, guide Dams
carefully built and aim for sustainable development.
f. Implication of heavy rainfall warning by the nodal weather
forecasting agency of the country and nation’s capability to
know precondition before “heavy rainfall” in Uttarakhand have
become crucial issues. Mere deployment of advance weather
forecasting system in the region may not suffice the need of the
affected society until country’s knowledge institution work
together to devise “cloud burst” forecasting system. It’s required
to identify the gap between theory and practice in weather
modelling by making scientific research more relevant to
decision makers and for those agencies involved in post-disaster
reconstruction and risk reduction.
g. Realising that high population densities living in informal and
highly vulnerable settlements in hill areas of Uttarakhand - how
effectively the benefits of participatory and owner-driven
reconstruction process be initiated for Uttarakhand through
various rural reconstruction programs, where social networks
are stronger, and innovative building technologies are affable to
construction workers.
h. The seismic fault-lines of this earthquake-prone state were not
kept in mind while building roads and other
infrastructure. These tectonic fault-lines have been cut for roads
where seismic movements in the fault-lines are to be accounted
for.
6.1 Roads and Slopes
The non-engineered roads construction practices in most of the
damaged areas in Uttarakhand and roads conditions seen before the
heavy rain often corroborates that rain fall is the main reason for
landslides. However, in some of the cases, utmost care is taken to
maintain atleast a healthy drain system along the road but the same
is not continued routinely for majority. It is true that the state is
located in the midst of young and unstable mountains and the area is
subjected to intense rainfall but neither of these characteristics can
cause substantial damage to the roads/infrastructure, if they were
constructed following technical guidelines available in the country.
The landslide problems around the Monsoon occur not because of
the steep slopes, but because no attention is paid to the stabilization
of roads and its allied components in scientific manners. Some of
the perennial landslides problems in India have been tackled by
Border Roads Organization (BRO) well.
While in the neighboring state of Himachal Pradesh in India,
Himalaya, taking advantage of the hard rocky strata, roads
infrastructure created decades ago (Figure 8) have been functioning
well, the long term performance of these roads requires continuous
monitoring. Geotechnical intervention in such road networks are
minimal and hence in the reconstruction phase of the post-flash
flood due importance are to be accounted for.
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
Figure 8: Road construction on rocky mountain in Himachal
Pradesh, India remain undisturbed till stability of the rocks are
tested by earthquakes and other hazards in the vicinity
Figure 9a shows one of the many roads in the hilly areas that goes
out of order due to poor drainage resulting that they require proper
geotechnical measures. In many cases such problems, can be
mitigated by providing perforated drains as shown in Fig. 9b and the
drained water can be tapped for other uses (inset Figure 9b)
Figure 9: Incipient cross drainage due to heavy rain fall during
Uttarakhand flash flood (2013) and suggested simple correction
measures by inclined drain. Inset image showing application site of
the same
Figure 10a shows the disruption of the roads in Uttarakhand and
defying the role of proper placement as well as proper maintenance
of cross drainage. As a recovery measure for such situation, Figure
10b, shows one of the ways to to look into such problems. Figure
11a, shows one of the severe landslides in Uttaarakhand state that
remained unsolved by simple measures of slope protection, e.g.
retaining walls, gabion mat, soil nailing, etc. The reality mitigating
such slopes by multi agency and multi-objective control measures is
shown in the Figure 11b.
Figure 10: Torrential water flow severed the road link thus
disrupting the communication. Lots of debris and muck formed out
of flash flood might have caused such problems, for which adequate
culvert or aqueduct were not in place. Suggested restoration
measures with Geo-net protecting the culvert
Figure 11: a) Typical facets of fragile slope in Uttarakhand state and
multi-purpose and b) multi-objective of typical slope stabilization in
Japan (Source: Ministry of Land, Infrastructure, Transport)
(a)
(b)
(b)
(a)
(a)
(b)
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
6.2 Modern slope stabilization measures
While flash flood induced geotechnical failures were found in plenty
in the state of Uttarakhand, it’s also important to be aware of the
typical stabilization measures for normal slopes, some of which are
exemplified in Figures 12 to 18.
Use of rubble masonry is a routine practice in the hill roads (Figure
12a) and vulnerability of such type of protection measures
especially during heavy rainfall requires no special mention.
However, typical soil nailing option as shown in Figure 12b or for
some of the ongoing National Highways construction in the
neighbouring state of Himachal Pradesh, where massive rouble
masonry wall constructions are followed (Figure 13a), application of
nailing technique followed elsewhere (Fig. 13b), can be adopted for
the reconstruction hill slopes ravaged the flash flood in Uttarakhand.
In Figure 14a, slope protection measures taken as such can be made
performing better during heavy rain fall by application of geonet or
geogrid as typically shown in Figure 14b. Even in some of the
convention rubble masonry slope protection walls as shown in
Figure 15, the inclination of the week hole pipes, go out of order due
to poor maintenance. In such cases composite geosynthetics layers
can be used to keep drainage operational during extreme weather
events.
Figure 12: Conventional method of Stone masonry wall (a) vs. Soil
nailing (b) that typically used for stabilizing slopes
Figure 13: Typical road side hill slope protection measure in hilly
areas vs. Nailed slope in Japan
Figure 14: Unprotected slope vs. Protection by geo-net
(a)
(b)
(b)
(a)
(a)
(a)
(b)
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
Figure 15: Provision of weepholes in normal construction and ill
performance due to poor maintenance
Many Dams during flash flood, went out of order due to excessive
erosion and water currents. The documentation of the damages and
loss has not been done yet but in the case of one Dam, which was
newly built and yet to start operation (Figure 16a) at the Srinagar
town of Uttarakhand, it has removed the silts deposit about 200m
away downstream due to release of water through sluice gate and
thus filled up valley town with 2 to 5m thick silt load as shown in
Figure 16b. As many of the existing building in the Srinagar town,
came under silt, during reconstruction densification of the same can
be achieved by geosynthetic vertical drains.
Figure 16: Silt deposit at Srinagar, Uttarakhand due to water release
by the Dam
6.3 Bio-engineering measures
Realizing that heavy rain fall induced flash flood carries everything
that come on its way; it’s high time to look into the reconstructions
measures that must be sustainable. It is very much possible to adopt
slope stabilization measures by combination of reinforced earth, soil
nailing, etc technique with bio-engineering measures by Vetiver
grass (Truong and Baker, 1996; Dalton et. al, 1996). Climate
change/extreme weather phenomena and impact of deforestation and
changes in the flora-fauna of mountains, possibly due to
multipurpose hydro power projects and other tourism-driven
vulnerable establishments along the towns and river banks needs to
be assessed. Though it’s not yet possible to bring all climate related
facts into one fold and justify the cause-effect role, at least
reconstruction measures can take care of the landslides and erosion
control measures by local yet simple techniques. This section
provides the application of Vetiver grass, which is primarily of
Indian origin, but routinely used by more than 120 countries. Some
of the potential applications in the North East part of India wherein
proper methodologies along with some successful examples are
explained.
6.3.1 Application areas:
a. Landslides scenario in the country – highlighting
ineffective/inadequate drainage/stabilisation measures that
leads to progressive failure
b. Hill widening by cutting hills vs. man-made landslides
c. Live landslide hotspots vs. inappropriate technological
overtures
d. Landslides prevention measures by conventional slope
stabilisation methods, such as gravity retaining walls vs.
modern techniques using geosynthetics
e. Important hill roads where slope stabilization measures are
taken with extremely high cost vs. bio-engineering measures
ensuring better safety with low or no cost
f. Vetiver grass – it’s origin, properties and potential for erosion
and landslide control
g. Successful Application of Vetiver grass where conventional or
many other methods failed but Vetiver caused complete
solution with hardly any cost and maintenance
h. Application of Vetiver grass – giving examples of successful
and failed application in India/abroad and signifying the role of
Vetiver grass for long term solutions
i. Guidelines for Vetiver application siting several examples of
landslides hotspots exclusively or in combination with
conventional slope retaining structures
Excepting a mere mention in the recent Indian Road Congress (IRC)
code for the application of Vetiver system, many nodal
organizations in the country are hesitant to adopt Vetiver system
(VS). However, a combination of modern techniques with Vetiver
system has to be emphasized and in order to harness that geo-
professional practices need to evolve technique to apply bio-
engineering solution in soil erosion and landslides problems.
Following considerable research and the successes of the many
applications presented elsewhere, it is now established that Vetiver,
with its many advantages and very few disadvantages, is a very
effective, economical, community-based and environmentally-
friendly sustainable bioengineering tool that protects infrastructure
and mitigates natural disasters. Once established, the Vetiver
plantings will last for decades with little, if any maintenance.
However, it must be stressed that the most important keys to success
are good quality planting material, proper design, and correct
planting techniques.
6.3.2 Characteristics of Vetiver system
Vetiver’s unique attributes have been researched, tested, and
developed throughout the tropical world, thus ensuring that Vetiver
is really a very effective bioengineering tool:
(a)
(b)
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
• Although technically a grass, Vetiver plants used in land
stabilisation applications behave more like fast-growing trees
or shrubs. Vetiver roots are, per unit area, stronger and deeper
than tree roots.
• As strong as or stronger than those of many hardwood species,
Vetiver roots have very high tensile strength that has been
proven positive for root reinforcement in steep slopes.
• These roots have a mean tested tensile strength of about 75
Mega Pascal (MPa), which is equivalent to 1/6 of mild steel
reinforcement and a shear strength increment of 39% at a
depth of 0.5m
Typical man-made slope instability problems created during hill
road widening process, for which conventional solution is not either
possible or economically feasible (Figures 17a and b) can be
stabilized by combination of small height breast wall and Vetiver
plantation as shown in Figure 18 a and b. The feasibility planting
vetiver grass even in the 90o angle hill cut is possible and the
stability of such slopes are exemplified. In order to propagate this
technique, a good deal studies, specially suitability of the Vetiver
grass at different geo-climatic conditions are to yet to catch the Geo-
professional domain studies and rightful practices to solve many
unsolvable slope stability problems by conventional methods. But
the wide scale erosion due to flash flood in Uttarakhand (Figure
19a) and potential danger awaiting for the India’s highest Dam
constructed decades back in the same state (Figure 19b), where
hydroelectric power generation is often limited by the fast
drawdown induced erosion are yet to be tackled by the current
geotechnical practices in the country.
Figure 17: Stabilisation measures for natural and man-made cut
slope in hill areas in Uttarakhand await geotechnical intervention
Figure 18: Typical application of Vetiver grass in the State of
Assam, India as a viable cost effective alternative for slope
stabilization
Figure 19: Some of the unsolved slope and erosion areas in
Uttarakhand (a) along the Mandakini river and (b) Tehri Dam
reservoir
(a)
(b)
(b)
(a)
(a)
(b)
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 48 No. 1 March 2017 ISSN 0046-5828
7. CONCLUSIONS
An effective reconstruction program for the Uttarakhand is required
for rebuilding state economy and reducing financial and societal
interruptions. Reconstruction works must start with the geotechnical
evaluations to identify vulnerable establishments in the State by
initiating damage surveys and looking into the erstwhile design
practices, construction methods, and building materials that either
failed under the forces generated by the heavy rain fall induced flash
flood or were successful in resisting such forces. In addition, the
reconstruction efforts should also look at land use management and
planning practices, as well as natural/man made hazard
identification and risk assessment. This is to be done in an effort to
learn whether actions of the Government, other than those involved
in designing and constructing buildings/dams/roads along the river
valleys and temple towns in Uttarakhand are up to the mark in
minimizing damages from natural hazards, including earthquakes.
For the disaster prone area in Uttarakhand, there should be always
an existing emergency disaster plan for better coordination among
the various agencies in the district or at the disaster. Given the
current policy of the State Government of pursuing hydro-power
projects, the potential cumulative effect of multiple run-of-river
power projects can turn out to be environmentally damaging but it’s
urgently required to have technical auditing of these projects. The
impact of environmental concerns required to be assessed by geo-
professionals, for which Indian Government has to device policy
frame work beyond the jurisdiction of normal EIA procedure that
not feasibly accountable for the damaged caused by recent flash
flood.
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