Satellite detected water extents in Vatovavy Fitovinany region, Madagascar as of 8 February 2022

Name: Satellite detected water extents in Vatovavy Fitovinany region, Madagascar as of 8 February 2022
Creator: United Nations Satellite Centre (UNOSAT)
License: http://www.opendefinition.org/licenses/cc-by-sa

✦ DISCOVERED BY ORIONAIUnited Nations Satellite Centre (UNOSAT)WaterMadagascar

Madagascar

About this dataset

**UNOSAT code: TC20220201MDG** This map illustrates satellite-detected surface waters in Vatovavy Fitovinany region, Madagascar as of 8 February 2022 at 05:20 local time. The flood analysis were carried out by using an automated analysis with Artificial Intelligence based methods. Within the analyzed area of about 3,800 km2, 210 km2 of lands appear to be flooded. Based on Worldpop population data and the detected surface waters in the analyzed area, the potentially exposed population is 57,200 people mainly located in district of Vohipeno with ~ 30,000 people, and Manakara Atsimo with ~ 27,000 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.

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.

Related datasets

Satellite detected water extent in Vohipeno District, Vatovavy Fitovinany Region, Madagascar as of 05 January 2024

**UNOSAT code: TC20240102MDG, GDACS ID: 1001040** This map illustrates satellite-detected water extent in Vohipeno District, Vatovavy Fitovinany Region as observed from a Sentinel-1 image acquired on 05 January 2024 at 05:20 local time. Within the extent of this map of about 600 km², a total of about 50 km² of lands appear to be affected with flood waters. Based on Worldpop population data and the detected surface waters, about 17,700 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 the 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.