16th of December 2021 Tropical Cyclone RAI-21, Philippines. Preliminary Satellite-Based Comprehensive Damage Assessment

Name: 16th of December 2021 Tropical Cyclone RAI-21, Philippines. Preliminary Satellite-Based Comprehensive Damage Assessment
Creator: United Nations Satellite Centre (UNOSAT)
License: http://www.opendefinition.org/licenses/cc-by-sa

✦ DISCOVERED BY ORIONAIUnited Nations Satellite Centre (UNOSAT)EnvironmentPhilippines

Philippines

About this dataset

**UNOSAT code: TC20211216PHL** A category 5 Tropical Cyclone RAI-21 struck the Philippines on the 16th of December 2021, causing damage, devastation, and destruction. The Tropical Cyclone RAI-21 made landfall north of General Luna city on Siargao Island, the easternmost island of the Philippines, and continued westward through the central part of the country. The Philippines National Disaster Risk Reduction and Management Council (NDRRMC) has stated that 2,182,791 families have been affected in 11 out of 17 regions of the Philippines. About 3M people, ~ 30% of the affected area population – need emergency humanitarian assistance. According to OCHA, the death toll has reached 177 persons, with more than 275 persons injured and 630,000 displaced. More than 159,000 houses have been damaged, 61,900 have been destroyed. These figures are likely to rise as the after-effects of the Tropical Cyclone are fully realized. Preliminary assessment has shown devastating damage to houses, roads, and bridges disrupting aid movement into the affected areas. This report summarizes satellite-derived building damage analysis covering the most affected areas within Region IV-B (Mimaropa), Region VII (Central Visayas), Region VIII (Eastern Visayas), and Region XIII (Caraga) of the Philippines.

Documentation

UNOSAT datasets and maps are produced using a variety of methods. In general, analysts closely review satellite imagery, often comparing two or more images together, and determine notable changes between the images. For damage assessments, refugee or IDP assessments, and similar analyses, these changes are then manually documented in the vector data by the analyst. For flood extractions, landcover mapping and similar analyses, a variety of automated remote sensing techniques are used to extract the relevant information which is then reviewed and revised as necessary by the analyst. In all cases, resulting data is then loaded into a standardized UNOSAT geodatabase and exported asshapefiles for dissemination. This is a preliminary assessment and has not yet been validated in the field. It is important to consider the characteristics of the source imagery used in the analyses when interpreting results. For damage assessments it should be noted that only significant damage to the structural integrity of the buildings analyzed can be seen in imagery, while minor damage such as cracks or holes may not be visible at all. For flood extractions using radar data it is important to note that urban areas and highly vegetated areas may mask the flood signature and result in underestimation of flood waters. Users with specific questions or concerns should contact unosat@unitar.org to seek clarification.

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Damage assessment in Siargao Island, General Luna, Surigao del Norte of Philippines as of 26 December 2021

**UNOSAT code: TC20211216PHL** This map illustrates potentially damaged structures/buildings in Siargao Island, General Luna, Surigao del Norte of Philippines as detected by Pleiades image acquired on 26 December 2021 and WorldView-3 acquired on 23 December 2021. Within the analyzed area, UNOSAT has identified 1,769 damaged structures, 380 potentially damaged structures. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to the United Nations Satellite Centre (UNOSAT).