2. Philippines
The particular geographic and
geological setting of the
archipelago makes it naturally
prone to landslides, which can
be triggered by a single
volcanic, earthquake and
hydrogeological event or by a
combination of them.
With a rapidly growing
population and the continuous
demand for new lands, locals
are exposed to high risk
landslide events.
3. Tableofcontents
• Definition of Landslide
• Current methods of mitigation
• Bioengineering techniques and their uses in SE Asia
• Landslides in the Philippines
• Conclusion
4. Landslides
Landslides are commonly defined as down slope movements of soil,
sediment and rock.They take many different forms and are common
everywhere around the world but there are certain areas in which these
kinds of events occur more frequently.
5. CurrentMethodsofMitigation
Alteration of Slope Geometry
One of the most efficient ways of increasing safety, unsafe
material can be removed and replaced with stronger
matter. Benching or dividing a slope into segments can also
improve its stability.
6. Retaining Walls
Structures that retain
any material and
prevents it from
or eroding away.
used where there is a
lack of space for the
development of a
They can be divided
different types:
1. Gravity Wall
2. Brick
3. Stone
4. Reinforced Soil
5. Hybrid System
Current Methods of Mitigation
7. Landslide Warning Systems
They provide a rapid means of monitoring and communicating
information to vulnerable communities. Warning systems are
used to protect lives by indicating when landslides are likely to
providing time for notification and evacuation.
Current Methods of Mitigation
8. Pro: Very effective in mitigating landslide hazards
Con: Very expensive to build and to maintain; require
specialised training and are not suitable for developing
with limited budgets.
Current Methods of Mitigation
9. BioengineeringMethods
They rely mainly on the use of native plant materials, such as plant
stems or branches, rock, wood or soil.Appropriate vegetation can be
obtained from local sources of willow, alder and other native and
easily propagated varieties.
These systems are environmental compatible as they are visually non-
intrusive and blend naturally with the surroundings.As they require
minimal access to equipment and workers, they are feasible for
projects with tight budgets.
10. BioengineeringMethods
Natural RetainingWalls
Riprap – layer of large stones thrown together without order
Crib walls – can be built from natural materials like rock and timber
Gabions – rectangular blocks filled with rock and soil; held together by a
mesh basket in steel wire or natural fibres such as bamboo
These methods are the cheapest versions of normal retaining
structures.
11. Live Plants as Bioengineering Measures
Live staking consists of inserting and tamping live branch cuttings
into holes in the ground. Over time, the live stakes create a living root
mat that binds together the soil particles.
Plants like vetiver are also used to stabilise soil with its deep root
system.
BioengineeringMethods
12. Examplesofeffectiveslopestabilisationthrough
bioengineeringinSEAsia
1. Bangladesh – a few trials have been conducted using vetiver.
Results show a sufficient capacity in stabilising slopes from
rain, cut erosion and sliding.
2. Vietnam – has been using these methods for natural
disaster mitigation. Vetiver is very popular, especially when
combined with riprap wall and bamboo.
3. Hong Kong – vetiver has been used in holes with hard slope
cover to increase the effective stability of the area.
4. Philippines – drainage and riprap retaining walls are used
extensively.
14. Payatas 2000
The municipal solid waste slide mobilised after heavy rain. 278
people died and 650 others went missing.
ExamplesofRecentLandslides
inthePhilippines
15. Leyte 2006
A rock slide avalanche buried the entire village of Guinsaugon.
Starting out as a block slide, it turned into an avalanche,
causing the death of 1119 people and destroying millions’ worth
in properties.
ExamplesofRecentLandslides
inthePhilippines
16. Baguio City 2009
In October 2009,Typhoon Pepeng hit the Philippines, causing a
flood and a landslide that killed 501 people in the area of
Baguio.
ExamplesofRecentLandslides
inthePhilippines
17. Conclusion
Would bioengineering methods have mitigated those landslides and
prevented the loss of property and human lives?
Cherry Hills
Panaon
Baguio City
Over steeped
slopes
Bohol
Leyte
Deep seated
and involved
the rock
underneath
Payatas
Collapse of
unstable landfill
Bioengineering
would not have
been effective
against them
The only case where bioengineering techniques would have been effective
was the landslide in Quezon because it only affected superficial soil.
Location Reason for slope failure
18. Bioengineering techniques should only be seen as
complementary methods for slope stabilisation, to be used in
conjunction with ordinary methods.
In countries such as the Philippines, it is better to use existing
budgets to educate the local population.
The main focus should be on:
Conclusion
Risk Perception
Safe Behaviours
Response to Warnings
Involvement of General Population
