Landslide Mapping in Nepal

Landslide Mapping in Nepal
the impacts of the Gorkha earthquakes and the monsoon
Colm Jordan
Tom Dijkstra
Stephen Grebby
British Geological Survey
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Alex Densmore
Nick Rosser
Jack Williams
Mark Kincey
Durham University
Nepal Landslide Mapping 2015
In May 2015 the UK Government requested rapid and frequent
advice from the British Geological Survey and Durham
University on the impacts of the Gorkha earthquake-induced
landslides on housing, infrastructure, rivers etc.
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We used satellite imagery to produce landslide inventories to underpin the
advice
The UK team also integrated international mapping into the inventories
Outputs
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Landslide inventory maps
Landslide inventories (databases) updated frequently
Results released openly and used by national and international agencies
and Govt. ministries e.g. UNOSAT, World Food Programme etc.
Ongoing landslide response
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We are now working on monthly inventories of monsoon rainfallinduced landslides using satellite imagery and web/social media
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Landslide Inventories: dates and format
Delivered on:
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4th May (> 400 landslides)
5th May
8th May (>3000 landslides)
30th June
5th August
28th August
…next one is being prepared
…and more to follow.
Inventory format:
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PDF Maps
Spatial database (GIS) e.g.
shapefile and GoogleEarth KMZ
Point/line/polygon per landslide
with map grid reference
Date of source satellite image
Landslide type
Confidence level
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Harmonisation:
The urgency to provide post-earthquake information led to variable
landslide metadata e.g. different sets of attributes recorded by
different agencies and often low resolution satellite images used
A lot of work and coordination is required to normalise the landslide
representations and attributes
Ongoing Monsoon Landslide Monitoring
Satellites are being specially tasked to collect images
throughout the monsoon
Purple - Radarsat ascending; yellow – Radarsat descending; red – very high resolution optical over four sites
We are also using
web and social
media (twitter)
trawls for landslide
monitoring during
the monsoon
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Ongoing Monitoring in the Upper Bhote Kosi
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Installation of landslide monitoring equipment at 10 sites in the Upper Bhote
Kosi, Sindhupalchok, to investigate the mechanics of post-earthquake slope
failure in collaboration with NSET-Nepal and BGS, funded by NERC Urgency
Study of how science is used in post-earthquake response and recovery, and
how the international research and humanitarian communities could work
together more effectively in future. Builds on EwF research before the
earthquake on the role of earthquake and landslide science in DRR
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Data Sharing & Coordination
The UK helped to coordinate international mapping efforts and compiled data
from NASA-ICIMOD volunteers, USGS, MDA and NGA into the inventories
We worked hard to ensure that the data are shared freely and openly on several
portals e.g.
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http://www.bgs.ac.uk/research/earthHazards/epom/Nepalearthquakeresponse.html
http://ewf.nerc.ac.uk/2015/05/28/nepal-updated-28-may-landslide-inventory-following25-april-nepal-earthquake/
• https://www.disasterscharter.org/image/journal/article.jpg?img_id=155056&t=14308234
47790
• https://data.hdx.rwlabs.org/group/nepal-earthquake
• http://www.mapaction.org/deployments/depldetail/240.html
• https://unosatgis.cern.ch/live/EQ20150425NPL/
• https://geohazards-tep.eo.esa.int/geobrowser/#!&context=Community
• https://umap.openstreetmap.fr/en/map/nepal-landslidescollection_41452#9/28.1507/85.3404
And that the results are ingested into e.g. Logistics Cluster for users such as the World
Food Programme
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Example of an international data portal
European Space Agency Geohazards Technology Exploitation Platform
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Next Steps for UK team (and others)
1. Produce additional monsoon landslide inventories (primarily from
satellite imagery, but also twitter reports)
• Harmonisation and standardisation required
• More image interpretation e.g. 13 August (19x22km) Pleiades image
showed 340+ landslides; continued mapping will form a very
valuable resource to better understand landslide triggering and
hazard in Nepal > working on September images now
2. Make the monsoonal landslide inventories and maps widely available
(recognising we are entering the reconstruction phase)
• Common platform(s) for inventories
3. Modelling: are the areas hardest-hit by the earthquake-triggered
landslides also the most-affected by monsoon-triggered landslides?
4. In-situ monitoring of some landslides (Upper Bhote Kosi)
5. Consider the future landslide susceptibility in Nepal
Are there members of the audience who have not seen our results, but
would like to have access or collaborate? Contact Colm Jordan at
CJJ@BGS.AC.UK
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Acknowledgements
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UK Department for International Development
European Space Agency
Committee on Earth Observation Satellites
MDA CSA – Radarsat (Marco van der Kooij)
UNOSAT - UNITAR
Natural Environment Research Council
International Charter, Space and Major Disasters
Imagery used: Cartosat, DMCii, EO-1, GeoEye, Landsat, Pleiades,
Radarsat, ResourceSat, SPOT, TerraSAR-X, WorldView
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Pre-earthquake DMCii image – Dhunche Area
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Post-earthquake Pleiades image – Dhunche Area
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Post-earthquake Pleiades image – Dhunche Area
(landslides highlighted in red)
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Relevant Social Media Posts in the last week
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