Landslides: Mitigation Measures
Summary
TLDRThis educational program delves into landslide mitigation strategies, emphasizing the importance of cost-effective measures using indigenous technologies. It outlines four primary mitigation types: altering hazards, averting impacts, adopting special building standards, and avoiding hazardous areas. The script covers various techniques such as drainage measures, slope grading, retaining walls, and vegetation reinforcement. It also highlights the significance of public awareness, participation, and the integration of geosynthetic materials in slope protection. The program underscores the need for a comprehensive approach involving inventory, risk assessment, and policy formulation for effective landslide management.
Takeaways
- 🛑 Landslides cause significant losses to life and property, highlighting the importance of mitigation measures.
- 💡 Mitigation efforts should be cost-effective and utilize indigenous technologies where possible.
- 🔄 Four types of mitigation strategies are altering, averting, adopting, and avoiding to manage landslide risks.
- 💧 Drainage measures are crucial, including controlled runoff water flow and sediment load management to reduce soil erosion.
- 🌊 Diversion of upstream rivers and underground drainage can help in preventing landslides in vulnerable areas.
- 🏗️ Slope grading and modification techniques like terracing can improve stability and reduce landslide risks.
- 🚜 Soil or debris removal, including creating benches and retaining walls, is effective for small to medium-sized landslides.
- 🌳 Afforestation and reinforced vegetation increase the shear strength of slopes and prevent erosion by surface water.
- 🌱 Geofabric and geotextiles are used in slope protection, providing initial erosion control until vegetation can take over.
- 🏰 Retaining structures like retaining walls and breast walls are essential for stabilizing slopes and preventing secondary landslides.
- 🚨 Awareness and public participation are vital components of landslide mitigation, including avoiding old landslide areas and maintaining infrastructure.
Q & A
What are the primary goals of landslide mitigation measures?
-The primary goals of landslide mitigation measures are to reduce the frequency of landslides, minimize the damage to life and property, and to use cost-effective indigenous technologies in the process.
What are the four types of mitigation measures mentioned in the script?
-The four types of mitigation measures are altering the hazards, averting the impact, adopting special building standards, and avoiding the hazard areas altogether.
Why are drainage measures important in landslide mitigation?
-Drainage measures are important because they control the flow of runoff water, reduce soil erosion, and prevent the buildup of pore pressure in sediments that can facilitate landslides.
What are contour drains and how do they help in landslide mitigation?
-Contour drains are channels made along different contours at reasonable intervals on slopes to direct surface water away, preventing percolation into the ground and thus reducing the risk of landslides.
What is the purpose of perforated drain piles in landslide mitigation?
-Perforated drain piles are used to control groundwater levels, which can build up pore pressure in sediments. They are made of materials like PVC or steel and are installed at an angle to allow water to drain, reducing the risk of landslides.
How does slope grading contribute to landslide prevention?
-Slope grading involves modifying the slope to improve its stability. Techniques such as slope benches, terracing, flattening slopes, and removing loose material can help reduce the risk of landslides.
What is the difference between a retaining wall and a breast wall in the context of landslide mitigation?
-A retaining wall is constructed in the valley side to prevent small or secondary landslides along the toe of larger landslides, while a breast wall is built on the hillside of the road to provide lateral support to the slope.
Why is soil or debris removal an effective measure for landslide mitigation?
-Soil or debris removal is effective because it involves removing the slide mass from the crown portion downwards, creating benches and constructing restraining structures like retaining walls, which prevent the reactivation of old landslides.
What role does vegetation play in landslide mitigation?
-Vegetation plays a crucial role in landslide mitigation by preventing erosion through natural anchorage provided by tree roots, which increases the shear strength of the slope material. Afforestation and reinforced vegetation also protect against rain and wind erosion.
How can geosynthetic materials like geogrid and geotextile be used in landslide mitigation?
-Geogrid and geotextile are used to reinforce soil and similar materials. They help in strengthening the slope, allowing vegetation to grow and hold the soil, thus preventing erosion and increasing the overall stability of the slope.
What is the importance of public awareness and participation in landslide mitigation?
-Public awareness and participation are vital in landslide mitigation because informed communities can take preventive measures, avoid high-risk areas, and contribute to the overall effort of disaster preparedness and mitigation.
Outlines
🏞️ Landslide Mitigation and Management
This paragraph introduces the topic of landslide mitigation and its importance for national safety and property protection. It emphasizes the need for cost-effective measures using indigenous technologies and outlines four types of mitigation: altering hazards, averting impacts, adopting special building standards, and avoiding hazardous areas. The paragraph also discusses various primitive measures, starting with drainage as a key strategy to reduce soil erosion, including methods like contour drains, diversion ditches, and underground drainage. It touches on the use of perforated drain piles for groundwater control and different types of drains for surface and subsurface water management. Additionally, it mentions slope grading and soil/debris removal as important measures for landslide prevention.
🚧 Structural Measures for Landslide Prevention
This section delves into structural solutions for preventing landslides, such as the construction of retaining and breast walls to provide stability to slopes and prevent secondary landslides. It differentiates between the two, explaining that breast walls are built on the hillside of the road, while retaining walls are on the valley side. The paragraph also covers other restraining structures like grip walls and the use of geosynthetic materials like geofabric and geogrid to reinforce soil. It discusses the importance of mulching and afforestation for erosion control and increasing the shear strength of slopes, as well as the use of grouting to strengthen moistened soil. The paragraph concludes with the mention of hydroseeding for vegetation growth and erosion control, and the use of rock bolts and mesh draping for rock mass stabilization.
🏘️ Human Settlement and Landslide Awareness
This paragraph focuses on the importance of evaluating geological suitability before allowing urban settlements on hill slopes. It stresses the need for public awareness about landslide-prone areas and the role of display boards in warning people. The text also highlights the significance of public participation in mitigation measures and the avoidance of areas with signs of old landslides. It suggests preventive measures such as relocating facilities, maintaining roadside drains, and following building codes and bylaws to ensure safety. The paragraph also discusses the importance of a comprehensive plan for disaster preparedness, including landslide inventory, risk assessment, and the use of remote sensing and GIS techniques for effective mitigation strategies.
🛡️ Community Involvement and Landslide Mitigation Strategies
The final paragraph wraps up the discussion on mitigation measures, emphasizing that the effectiveness of these measures depends on the site-specific conditions of landslides. It underscores the role of everyone in the community, particularly the importance of people's participation in managing landslides. The paragraph concludes by thanking the learners for their attention to the program, highlighting the collective effort required to tackle the challenge of landslides.
Mindmap
Keywords
💡Landslides
💡Mitigation Measures
💡Drainage Measures
💡Slope Stability
💡Retaining Walls
💡Geosynthetic Materials
💡Grouting
💡Afforestation
💡Risk Assessment
💡Public Policy
💡GIS and GPS Techniques
Highlights
Importance of mitigating landslides to prevent heavy losses to the nation and damage to properties.
Need for cost-effective measures using indigenous technologies for landslide mitigation.
Four types of mitigation: altering, averting, adopting, and avoiding landslide hazards.
Drainage measures as a crucial step to reduce soil erosion and control runoff water.
Use of contour drains and open diversion ditches to prevent water percolation in the ground.
Implementation of perforated drain piles to control groundwater and reduce pore pressure.
Slope grading techniques such as terracing and slope flattening to improve stability.
Soil or debris removal work as an effective measure for small to medium-sized landslides.
Construction of retaining and breast walls to prevent secondary landslides and stabilize slopes.
Difference between retaining walls and breast walls in terms of their location and function.
Use of geofabric and geogrid to reinforce soil and protect slopes against erosion.
Grouting of loose soil to increase its strength by injecting cement or lime slurry.
Hydroseeding as a process to control erosion and promote vegetation growth on slopes.
Prevention of rock falls using rock bolts and wire mesh in rock cuts and tunnels.
Importance of evaluating geological suitability before urban settlement on hill slopes.
Creating awareness and public participation in avoiding landslide-prone areas.
Structural mitigation measures including adherence to building codes and by-laws.
Landslide inventory and risk assessment for better planning and disaster preparedness.
Role of remote sensing, GIS, and GPS in preparing landslide hazard maps for mitigation.
Comprehensive planning and public policy formulation for hazard management.
Transcripts
so
[Music]
[Music]
dear learners
welcome
today in this program we will learn
about the
mitigation measures of the landslides
and its management well as we know the
landslides causes heavy losses to the
nation causes the loss of life and
damage to the properties so there is
very important
how we can mitigate with these
landslides
well there is a need to develop
appropriate measures for mitigating the
losses due to the landslides
it should be cost effective and most
important is that the effort should be
made to use indigenous technologies
well if we see the mitigation we can
have in four types
is altering
that is to modify the hazards involve
eliminating or reducing the frequency of
its occurrences
then averting that is redirecting the
impact away from a vulnerable location
by using structural device or land
treatment can shield people and
development activities from harm
and then adopting that means
pre-identified landslide hazards
requires special building standards and
construction practices in order to
reduce vulnerability to the damages
and then lastly the avoiding that means
they keep people away from the hazards
area or limit development in a risky
area there are various primitive
measures let's see one by one most
important is the drainage measures
suitable drain be made for the
controlled flow of runoff water which
will reduce soil erosion drainage
culverts must have the capacity to take
sediment loads otherwise it will choke
so we must take care of these small
things well upstream river should be
diverted from the landslide prone area
and underground drainage be made for
small channels
and streamlets while making the drains
there are different methods one is the
contour drain
contour drains may be made along
different contours at reasonable
interval
on slopes to channelize surface water to
prevent percolation in the ground
likewise open diversion ditches to
collect run of water on the hopple site
may be made and likewise catch water
drain connected to the near catchpit
areas are some of the best practices
well another important point is the
perforated drain piles may be
implemented to control groundwater which
otherwise built up pore pressure in the
sediments that facilitate landslide
perforated drain pipes are used where
ground water is significant which can be
judged from the seepage condition in an
area the pipes could be pvc or steel
fabricated
they are drilled at an angle of 15 to 20
degree nearly 3 meters below the ground
surface and length of the pipes depends
upon the site shallow surface drainage
include the interceptor subsurface
drainage horizontal gravity drain and
interceptor trench drain similarly for
subsurface drainage measures horizontal
drains vertical drains and deep trench
drains may be adopted as per site
specific requirement now another
important measure is the grading of
slope as we know that the slope is the
major cause of the landslide so we
should look into it the slope
modification techniques may be adopted
to improve slope stability
such as slope benches or terracing
flattening of slopes removal of float at
the slope head portion
and enlarging this toe of a slope these
not only reduces the slope but also trap
the sliding material and regular
monitoring of field slope should be
carried out for slow failures next
important is the soil or debris removal
work it is also known as geometry
modification measures these are
generally very effective in case of
small to medium sized landslides soil or
debris removal of this slide mass is
generally undertaken from the crown
portion
downwards in this process benches are
created at regular intervals depending
on the properties of the material
then construction of retaining walls and
breast walls these restraining
structures are constructed to prevent
small sized or secondary landslides that
often
occur along the toe of
larger landslides it also brings greater
stability to dangerous slopes now let us
see
the retaining wall and the breast wall
what is different between retaining wall
and the breast wall well breastfall are
made on the hill side of the road and
retaining walls are formed in the valley
side so the stout embankments backpacked
with boulders and gravels are
constructed at the toe of the slope on
the upper side of the road and heavy toe
butters of earth material are made for
lateral support of the slope whereas
retaining walls are constructed at an
angle of nearly 30 degree to sustain the
overweight grip walls this is another
type of restraining structure
it is mainly used where the material is
saturated
grip wall is a supporting wall
constructed by laying crips at right
angle to each other and these walls are
preferred instead of conventional
reinforced concrete retaining walls
gavin balls are also provided as
retaining structures where loose mass
exist on the slope while mulching and
adding ground cover this is an important
aspect where mulch protects against
rain and wind
and reduces loss of soil moisture during
extended dry periods then afforestation
and reinforced vegetation a thickly
vegetative slope prevents erosion by the
surface water because of natural
anchorage provided by the tree roots
thereby increasing shear strength of the
slope material
large size tree cuttings and removal of
vegetable cover
on hill slope should be stopped a
forestation is most commonly an
economical method applied in case of
treated slope on large scale
this not only provides effective
covering to the slopes to protect
erosion of soil and root material but
also the roots penetrate into the ground
helps in improving shear strength of the
subsurface material infrastructure
efforts required to adopt locally fast
growing varieties horticulture should be
given important than agriculture
especially in the hilly terrain then
another important measure is the
geofabric or choir jute mating geofabric
commonly used in slope protection work
it is made of natural material like coil
jute the quadruped matting is laid over
the slope and vegetation is allowed to
grow over it it is biodegradable it
initially protects the slope against
surface erosion till vegetation takes
over that role
geogrid and geotextile geogrid and
geotextile are geosynthetic material
that helps to reinforce soil and similar
material example of geogrid that permits
vegetation to grow fast and hold the
soil then grouting of loose and
moistened soil the strength of the
moistened soil may be increased by
injecting cement or hydrated lime slurry
into the soil mass under pressure grout
material such as lime cement sodium
silicate bitumen
etc is injected at high velocity through
a nozzle into bedding planes fractures
sand lenses etc it is commonly known as
short creed short creed it reinforce the
strength of the rock phase it includes
aggregate cement and water and may be
complemented by fine material chemical
adjectives and reinforcing fibers hydro
seeding is a process
where seed fertilizer lime
moisture retention polymer
tackifiers
and straw fiber mulch with water is
mixed in correct proportion to form a
slurry
and it is spread on the ground to grow
vegetation and it also controls erosion
well in case of
rock masses rock boards and wrap matches
are used in this process holes are
drilled at suitable interval so as to
pass through two or more chunks rock
board is a long anchor board to
stabilize rock blocks
it is mainly used in tunnels or rock
cuts and these are used to prevent rock
falls draping mesh is used to stop the
falling blocks it
reinforce the strength of the rock
masses
well human settlement on the hill slope
it is very important aspect the
geological suitability of this site must
be evaluated before giving clearance to
urban settlement on the hill slope
people normally build their houses just
on the hill slope by making a hill slope
into a table land without knowing the
engineering aspect of that
an important aspect of the mitigation
measure is also to create awareness
among the people and
they must be informed about the
landslide area so display boards may be
put at the areas which are prone to the
landslide to avoid accidents well public
participation is also equally important
as a part of the mitigation measure
we must avoid
the areas with old landslides
and the areas with the old length are
recognized by
occurrence of debris cover flatter
slopes occurrence of an awkward scar
along the break in the slope distinct
difference in the vegetation pattern
below
slight affected areas and adjacent areas
presence of spring along a curved line
presence of irregular drainage pattern
hunky nature of ground
a depression in longitudinal section of
a slope
these area may be avoided else the old
landslides are reactivated as you can
see in this photograph the old landslide
has been reactivated by the development
activities
well other preventive measures are
relocate or change the location of the
facilities to avoid landslide prone
areas we must construct developments
spurs check dams to protect slope
against river and stream erosion
roadside drains and culverts especially
during the raining season may be
regularly maintained to avoid
percolation of water
building construction on hill slope may
be avoided as far as possible but if it
is important it must be taken
the engineering design into the
consideration well
structural mitigation is also important
we must know the building codes and
building by-laws and we must follow them
building codes are for design and
material standards building permits
process inspections and licenses whereas
building bylaws are for enhancing safety
of new engineered construction to
acceptable risk we should not do things
like this as in this photograph you can
see a five-story building has been
erected on a drain without considering
its catchment that can bring enormous
amount of water
it is thus clear that
bull reliability to landslides combined
with other natural hazards and
socio-economic vulnerability of the
people living particularly in the hilly
region pose a great challenge to the
government the landslide hazards thus
need attention for comprehensive plan
for disaster preparedness and mitigation
well landslide inventory
includes the building up an inventory of
landslide that is the history of old
active and inactive landslides in an
important area
to be looked into which may form the
base information for undertaking further
detailed investigations and analysis for
designing optimal and effective action
plans
this will help in evolve integrated
mitigation
measures for landslides
using remote sensing
gis and gps techniques
landslide heather generation maps may be
prepared and make them available to the
concerned governmental and
non-governmental agencies for taking up
necessary measures is the prerequisite
in mitigating
the inside hazards landslide risk
assessment concerns
hazards and losses in terms of life and
properties it would help in generating
reliable database for better planning
and formulating various alternative
plans to minimize threat to human life
and property well monitoring and
analysis of the land size is an
important aspect the magnitude of
destruction depends on the location of
the landslide so recognition of precise
causes of landslide is very important
professor valdia
in 2002 has suggested formulation of a
public policy for hazards management and
strengthening of machinery
for coping with hazards risk through
public cooperation which are imperative
of the environmental security and
planning for development
dear learner
we
discussed about the mitigation measures
in this program
as we have seen there are various
mitigation measures
to check the landslides
but all depends upon the
site static conditions of the landslides
and as i mentioned about the management
of these landslides
everybody has a role to play
and the people's participation is very
important
the local community is very important
with this thank you
[Music]
you
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