Landslides: Mitigation Measures

Summary

This 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

00:00

🏞️ 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.

05:03

🚧 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.

10:03

🏘️ 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.

15:03

🛡️ 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.

Keywords

💡Landslides

Landslides are a type of natural disaster involving the movement of earth materials down a slope. They can cause significant loss of life and property damage. In the video, landslides are the central focus, with various mitigation measures discussed to prevent or reduce their impact.

💡Mitigation Measures

Mitigation measures refer to actions taken to reduce the severity or impact of a hazard. In the context of the video, these measures include altering, averting, adopting, and avoiding strategies to manage landslide risks, such as modifying the hazard, redirecting impact, using special building standards, and limiting development in risky areas.

💡Drainage Measures

Drainage measures are techniques used to control the flow of water to prevent soil erosion and reduce the likelihood of landslides. The script mentions the importance of suitable drains, culverts capable of handling sediment loads, and methods like contour drains and open diversion ditches to manage surface water.

💡Slope Stability

Slope stability is the ability of a slope to resist failure or movement under the influence of various forces. The video discusses slope modification techniques such as terracing, flattening slopes, and removing float to improve stability and prevent landslides.

💡Retaining Walls

Retaining walls are structural barriers used to hold back soil, rock, or other materials. They are mentioned in the script as a means to prevent secondary landslides along the toe of larger landslides and to provide stability to slopes.

💡Geosynthetic Materials

Geosynthetic materials, such as geogrids and geotextiles, are synthetic products used to reinforce soil and similar materials. The script explains their use in slope protection work, allowing vegetation to grow and hold the soil in place.

💡Grouting

Grouting is a process used to improve the mechanical properties of soil or rock. The video describes how grouting involves injecting materials like cement or lime slurry into the soil mass under pressure to increase its strength and prevent landslides.

💡Afforestation

Afforestation is the process of planting trees in areas where there was no previous forest. The script highlights afforestation as an effective method to prevent erosion by providing natural anchorage through tree roots, which increases the shear strength of the slope material.

💡Risk Assessment

Risk assessment is the process of evaluating the potential for harm or loss. In the context of the video, landslide risk assessment involves identifying hazards and estimating potential losses to life and property, which aids in planning and formulating mitigation strategies.

💡Public Policy

Public policy refers to the government's actions or plans to address particular issues. The script suggests the formulation of a public policy for hazard management and strengthening the mechanisms for coping with hazards through public cooperation as part of environmental security and planning for development.

💡GIS and GPS Techniques

Geographic Information System (GIS) and Global Positioning System (GPS) are technologies used for mapping and analyzing spatial data. The video mentions using these techniques to prepare landslide hazard generation maps, which can inform government and non-governmental agencies about necessary mitigation measures.

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