Satellite detected water extent as of 26 April 2021 in Leyte Province, Region VIII, Philippines

Name: Satellite detected water extent as of 26 April 2021 in Leyte Province, Region VIII, Philippines
Creator: United Nations Satellite Centre (UNOSAT)
License: http://www.opendefinition.org/licenses/cc-by-sa

✦ DISCOVERED BY ORIONAIUnited Nations Satellite Centre (UNOSAT)WaterPhilippinesSource offline

Philippines

About this dataset

**UNOSAT code: FL20220412PHL** This map illustrates satellite detected waters, the potentially exposed population, and the related potentially affected croplands as deduced using a satellite TerraSAR-X image acquired on 26 April 2021 at 05:34 local time acquired over Leyte Province, Region VIII, Philippines. Within the analyzed area of about 30,000 hectares, a total of about 2,000 hectares of lands appear to be flooded. The water extent appears to have increased of about 900 hectares since 21 April 2021. Based on Worldpop population data and the detected surface waters, about 8,000 people are potentially exposed or living close to flooded areas. The exposed population appears to have increased with about 3,000 people since 21 April 2021. In this area, about 1,800 km2 of croplands appear to be likely affected by the flood waters. The affected croplands seems to have increased with about 900 hectares since 21 April 2021. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to United Nations Satellite Centre (UNOSAT). Important note: Flood analysis from radar images may underestimate the presence of standing waters in built-up areas and densely vegetated areas due to backscattering properties of the radar signal.

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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Satellite detected surface water extents in Bulacan, Nueva Ecija, Pampanga, and Tarlac Provinces, Region III, Philippines as of 3 November 2022

**UNOSAT code TC20221028PHL, GDACS Id: 1000942** This map illustrates the extent of surface waters in Bulacan, Nueva Ecija, Pampanga, and Tarlac Provinces, Region III, Philippines as observed from a TerraSAR-X image acquired on 3 November 2022 at 05:59 local time. Within the analysis extent of about 1,800 km2, approximately 160 km2 of land appears to be inundated and 140 km2 of croplands appear to be likely affected by the flood waters. Based on Worldpop population data and detected surface waters, approximately 84,000 people are potentially exposed or living close to flooded areas. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to United Nations Satellite Centre (UNOSAT). Important note: Flood analysis from radar images may underestimate the presence of standing waters in built-up areas and densely vegetated areas due to backscattering properties of the radar signal.