Mapping the Impacts of Typhoon Goni inCatanduanes
Geomatics for Environment and Development
MANILA OBSERVATORY
November 9, 2020

Summary• Low-lying municipalities (with elevation less than 10 meters
above sea level) were flooded (flooded extent was estimated
2to be 4.3 km ) due to rainfall exceeding 150 mm during theonslaught of Typhoon Goni in Catanduanes.
• 1,577 people or less than 1% of Catanduanes’ population
were flooded.
• Buildings in different parts of the province were damaged.
More than 10,000 houses were damaged.

Low-lying Areas in Catanduanes

Typhoon Goni (Nov. 1, 2020)

Low-lying municipalities:
Viga
San Andres (Calolbon)
Virac
Panganiban (Payo)
PandanCaramoran

Bato
Bagamanoc
BarasGigmoto
San MiguelFlooded Areas in Catanduanes

Typhoon Goni (Nov. 1, 2020)24-hour Total Rainfall
Global Precipitation Measurement (GPM)
31 Oct 8 PM – 1 Nov 8 PM
http://sharaku.eorc.jaxa.jp/GSMaP_NOW/index.htm• Highlighted in blue are the observed flooded areas
in Catanduanes (4.3 km2) after >150 mm of rain
due to Typhoon Goni on Nov. 1, 2020.
• Flood was detected by thresholding the difference of pixel
values of Sentinel-1 SAR image taken on Nov. 1, 2020 andOct. 2, 2020 in Google Earth Engine.
• Please note that flood extent could be underestimated inurban areas due to complex backscattering over built
surface.
• Note also that no ground validation was done for this map.

11 Flooded municipalities in Catanduanes
Bato
San Miguel
ViracViga•

Panganiban (Payo)
San Andres (Calolbon)
Caramoran
Bagamanoc

SAR – Synthetic Aperture Radar

GigmotoPandanBaras

Flooded Areas in Catanduanes

Typhoon Goni (Nov. 1, 2020)

Flooded Population in Catanduanes

Typhoon Goni (Nov. 1, 2020)

Estimated Population in Flooded
Municipalities• Roughly 1,577 or less than 1% of
Cataduanes’ population wereflooded.
• This estimation is based on thedetected flooded area and PSA’s
barangay population data of 2015.
• More than 100 residents wereflooded in Bato, Virac, Panganiban,Viga.
••

PSA – Philippine Statistics Authority
SAR – Synthetic Aperture RadarAffected Population in Catanduanes as of Nov. 8, 2020

Typhoon Goni (Nov. 1, 2020)• NDRRMC reported that Goni affected atotal of 66,954 persons inCatanduanes, 25% of the province’s
population.
• Virac, San Andres, and Baras have thehighest number of affected population(>8,000 persons).
•NDRRMC – National Disaster Risk Reduction and Management Council

Damaged Buildings in Catanduanes

Typhoon Goni (Nov. 1, 2020)• Highlighted in yellow are the location ofbuildings and in red the possible location ofbuilding damage due to inundation and strong
winds of Typhoon Goni.
• NDRRMC reported a total of 12, 656 damaged
houses of which 4,814 were totally damaged
and 7, 842 were partially damaged.
•••

•
••
•
•

Building locations were from OSM.
Damaged areas were detected using synthetic aperture radar dataof Sentinel-1 of European Space Agency by ARIA-SG team of Earth
Observatory of Singapore (EOS) in collaboration with NASA-JPL andCaltech.
Please note that no ground validation was done for this data.

NDRRMC – National Disaster Risk Reduction Management Council
OSM – Open Street Map
AI – Artificial IntelligenceNASA - National Aeronautics and Space Administration
JPL – Jet Propulsion LaboratoryDamaged Buildings in Catanduanes

Typhoon Goni (Nov. 1, 2020)

abacbcDamaged Houses in Catanduanes

Typhoon Goni (Nov. 1, 2020)• NDRRMC reported that Goni damageda total of 12,656 houses inCatanduanes.
• Virac, San Miguel, Baras, Bato, San
Andres have the highest number ofdamaged houses (>1,000 houses).
•NDRRMC – National Disaster Risk Reduction and Management Council

Affected land cover in Catanduanes

Typhoon Goni (Nov. 1, 2020)• Based on this map, flooding affected22
2.7 km of annual cropland, 0.2 km of2barren/open area, and 0.2 km of
perennial cropland in the province.
• Note that the land cover data used was 5years old and that flood detection fromradar images tends to be underestimated.

• Aside from the agricultural damage
caused by floods, crops were also
damaged due to strong winds.

Typhoon Goni (Nov. 1, 2020)

Typhoon Goni (Nov. 1, 2020)

Typhoon Goni (Nov. 1, 2020)

For queries, requests, comments, suggestions, pleaseemail manila@observatory.ph