Landslide Risk Reduction in Sri Lanka2016/12/01 · Landslide Risk Reduction in Sri Lanka Eng (Dr.)...
Transcript of Landslide Risk Reduction in Sri Lanka2016/12/01 · Landslide Risk Reduction in Sri Lanka Eng (Dr.)...
Landslide Risk Reduction in Sri Lanka
Eng (Dr.) Asiri Karunawardena, Director General,
National Building Research OrganisationSri Lanka
Landslides in Sri Lanka
• Landslides have become a frequent natural hazard in central
highlands of Sri Lanka, which disturbs its life, causes damage to
property, constructed facilities and infrastructure.
• Nearly 20% of the land area from 65,000 sq. km of total area in
Sri Lanka is identified as landslide prone. Nearly 30% of total
population live in these areas.
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No. of Deaths
Number of lives lost due to landslides/slope failures:2000-2017
Landslide Potential Area
Landslides in Sri Lanka
Ladupita,Kiriwanella- Nuwara Eliya District 2007Paradeka - 2006
Mulhalkele 1986 Watawala 1991-92
Kalawana 2003
Ratnapura 2003
Ratnapura 2003
Padiyapelella 2007
Peradeniya 2006
Reactivation of Beragala Landslide (BadullaDistrict) 2009
Landslides in Sri Lanka
Landslide along major roads
Outer BoundaryKahagolla Landslide
Pilimathalawa 2007 Nildandahinna - 2007
Damages due to Unplanned Construction
Recent Cutting Failures
Non Engineered Construction Leading to Cutting Failures Along Main Roads
Landslides in Sri LankaMain triggering factor- Rainfall
2014-06-01
2014-10-29, Meeriabedda
2014-12-26
Our Strategies In Landslide Risk Management
• Landslide identification and hazard zonation mapping
• Integrate from Hazard to Risk management
• Landslide monitoring and early warning and awareness
• Landslide risk assessment for development and construction projects
• Landslide Special Investigations
• Structural mitigation works
• Related policy development and planning
Former Landslide
Slope range and slope category
Bedrock geology and Structure
Colluvium and
Landform and Erosion
Hydrology and Drainage
Rainfall
Human Settlements & Infrastructure
Landuse & Management
LANDSLIDE HAZARD MAP
*Ground Surveys
*Field Investigations
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Available Maps*
Unpublished materials
Residual soil
Key
Map
Attribute
Maps
Final Product
Mappin
g P
rocess
Terrain factors & Weightings
• BEDROCK GEOLOGY - 20
• SOIL COVER - 10
• SLOPE RANGE & CATEGORY - 25
• HYDROLOGY & DRAINAGE - 20
• LAND USE & MANAGEMENT - 15
• LAND FORM - 10
Allocated weights for attributes and
factor maps according to the statistical
analysis and experts knowledge
Landslide Identification & Hazard Zonation Mapping
Mapped Area
A typical hazard zonation map
Landslide Hazard Zonation Maps at different levels,
Regional, District & Local Authority level
Map of Kandy Municipal area
Map of Nawalapitiya Urban Council area
Landslide Hazard Zonation Maps
Development of Flow paths
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Day 2016.5.17_17:00
2016.5.18_ 0:00
Damage 28dead,99missing
DEVELOPMENT INTEGRATED LANDSLIDE HARZED MAPS
BUILDING FOOTPRINTS
INTEGRATED LANDSLIDE HAZARD ZONATION MAP
BUILDINGS EXPOSURE TO LANDSLIDE HAZARD
DATABASE ON ELEMENTS AT RISK – Data Base
Searchoption in different
levels
Retrieve datafrom selected area or
building
Investigation and Identification of
Vulnerable Communities and
High Risk Settlements
Details of the Risk Levels of the landslide prone locations at all
districts
# Province DistrictNumber of Houses inHigh Risk
1 Uva Badulla 6,418
2 Central
Kandy 1,292
Nuwara Eliya 3,496
Matale 210
3 SabaragamuwaRathnapura 757
Kegalle 824
4 SouthernMatara 591
Hambantota 343
5 Western Kalutara 929
DMC
NBRODOM
Pelmadulla
Elapatha Kahawatt
a
Nivithigala
Kalawana
Dynamic
Model
Early
Warning
Automatic Rainfall
Measurement System
Alert 75 mm/day
Warning 100mm/day
Evacuation, Off limit 75 mm/hour or 150mm/day
Warning and
Evacuation
Standard threshold limits
of the Rainfall for
landslides
Rainfall data is used in computer simulation and early warning is issued depending on threshold limits
Real Time Landslide Monitoring & Early Warning
• 100 automated rain gauge stations in pre-selected catchments in landslide prone districts
Schematic diagram of the socio-technical management system on
landslide early warning
Site specific/CB Monitoring, Forecasting and Early Warning
Extensometer
Data Logger for tilt sensor
Tilt Sensor
Protection Box
Extensometer
Invar Wire
Crack, Scarp Protection Pi pe
Movable Pile Protection Pipe
Landslide Movement
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Disp
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mm)
Extensometers and Groundwater Level for Badulla Landslide
SB-1
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Railfa
ll (mm
/day
)
Rainfall (mm/day)
Cumulative Rainfall (mm)
15- 27 Dec. 2014Cumulative rainfall: Total 652mm
8 Aug. -21 Dec. 2014Cumulative rainfall: Total 873mm
24 Dec 2014218mm/day
Cumu
lative
Rainf
all (m
m)
Horizontal Drainage Drilling 2016/6/15-Surface Drainage Ditch 2016/6/24-
2016/7/6 Fire Incident(SB-3,4)2016/8/1 Re-installation
15.7mm/3days
(7.6mm/day)10.0mm/2days
(5.8mm/day)
Instrumentation and Monitoring
Thank
you