Satellite detected waters in Ha Tinh and Nghe An Provinces of Viet Nam as of 18 October 2020

Name: Satellite detected waters in Ha Tinh and Nghe An Provinces of Viet Nam as of 18 October 2020
Creator: United Nations Satellite Centre (UNOSAT)
License: http://www.opendefinition.org/licenses/cc-by-sa

✦ DISCOVERED BY ORIONAIUnited Nations Satellite Centre (UNOSAT)WaterViet Nam

Viet Nam

About this dataset

**UNOSAT code: TC20201013VNM** This map illustrates satellite-detected surface waters in Ha Tinh and Nghe An Provinces of Viet Nam as observed from a Sentinel-1 image acquired on 18 October 2020. Within the analyzed area of about 9,000 km2, a total of about 500km2 of lands appear to be flooded. In Ha Tinh province, the water extent appears to have increased of about 300 km2 since 15 October 2020. Based on Worldpop population data and the detected surface waters, about 220,000 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 UNITAR-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 waters in Ha Tinh and Nghe An Provinces of Viet Nam as of 21 October 2020

**UNOSAT code: TC20201013VNM** This map illustrates satellite-detected surface waters in Ha Tinh and Nghe An Provinces of Viet Nam as observed from a Sentinel-1 image acquired on 21 October 2020. Within the analyzed area of about 8,000 km2, a total of about 300 km2 of lands appear to be flooded. In Ha Tinh province, the water extent appears to have receded of about 200 km2 since 18 October 2020. Based on Worldpop population data and the detected surface waters, about 100,000 people are potentially exposed or living close to flooded areas. The potentially exposed population is mainly located in the districts of Cam Xuyen with ~15,000 people, Can Loc with ~15,000 people and Thach Ha with ~15,000 people. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR-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.