Satellite detected water extents in Bolikhamxai and Khammouan Provinces, Lao PDR as of 28 July 2025

Name: Satellite detected water extents in Bolikhamxai and Khammouan Provinces, Lao PDR as of 28 July 2025
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

**UNOSAT code: TC20250722LAO, GDACS ID: 1001181** This map illustrates the satellite detected water extent in Bolikhamxai and Khammouan Provinces, Lao PDR as observed from Sentinel-1 satellite images acquired on 28 July 2025 at 05:50local time (22:50 UTC). Within the analyzed area of approximately 14,000 km², about 200 km² of land appears to be affected by floodwaters. Based on WorldPop population data and the flood extent, approximately 14,000 people are potentially exposed or living close to the 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 the 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 water extents in Vientiane Capital, Vientiane and Bolikhamxai Provinces, Lao PDR as of 27 July 2025

**UNOSAT code: TC20250722LAO, GDACS ID: 1001181** This map illustrates the satellite detected water extent in Vientiane Capital, Vientiane and Bolikhamxai Provinces, Lao PDR as observed from Sentinel-1 satellite images acquired on 27 July 2025 at 06:00 local time (23:00 UTC). Within the analyzed area of approximately 19,000 km², about 130 km² of land appears to be affected by floodwaters. Based on WorldPop population data and the flood extent, approximately 12,000 people are potentially exposed or living close to the 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 the backscattering properties of the radar signal