Satellite Detected Water Extent in the Phonhong & Viengkham Districts, Vientiane Province, Lao PDR

Name: Satellite Detected Water Extent in the Phonhong & Viengkham Districts, Vientiane Province, Lao PDR
Creator: United Nations Satellite Centre (UNOSAT)
License: http://www.opendefinition.org/licenses/cc-by-sa

✦ DISCOVERED BY ORIONAIUnited Nations Satellite Centre (UNOSAT)WaterLao People S Democratic Republic

Lao People S Democratic Republic

About this dataset

This map illustrates the satellite-detected water extent in the Phonhong & Viengkham Districts, Vientiane Province, in the northwestern part of Lao People’s Democratic Republic after the tropical storm SONCA-17. The UNITAR-UNOSAT analysis used a Sentinel-1 satellite image acquired on the 1 August 2017 and detected several areas with potentially standing waters. In the district of Phonhong 2,045 ha are likely flooded and in the district of Viengkham 1,077 ha. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR-UNOSAT.

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 Water Extent in Khamkeuth District, Borikhamxay Province, Lao PDR

This map illustrates the satellite-detected water extent in the district of Khamkeuth in Borikhamxay province, in the central-northern part of Lao People’s Democratic Republic after the tropical storm SONCA-17. The UNITAR-UNOSAT analysis used a Sentinel-1 satellite image acquired on the 11 August 2017 and detected several areas with potentially standing waters. In the district of Khamkeuth ~2,441 ha are likely flooded. Kindly note, the district of Khamkeuth has been partially analyzed due to the image does not cover the full district. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR-UNOSAT.