Night-Time Light Loss Assessment in Derna & Al Bayda (Libya) using Night-time Light Imagery

Name: Night-Time Light Loss Assessment in Derna & Al Bayda (Libya) using Night-time Light Imagery
Creator: United Nations Satellite Centre (UNOSAT)
License: http://www.opendefinition.org/licenses/cc-by-sa

✦ DISCOVERED BY ORIONAIUnited Nations Satellite Centre (UNOSAT)EnvironmentLibyan Arab Jamahiriya

Libyan Arab Jamahiriya

About this dataset

**UNOSAT code FL20230912LBY, GDACS Id: 1102204** Status: Significant light loss observed. Further action(s): Continuous observations planned for full assessment Severe floods in Libya have generated power supply outage in Derna and Al Baydā. About 5 km2 in Derna, and 4 km2 in Al Baydā became darker based on comparison of SDGSAT-1 images acquired before and after the floods. River delta area in Derna city lost the majority of night-time light, with power supply not fully restored as of 17 September 2023. In Al Baydā, power supply has been almost fully restored as of 17 September 2023. Continuous observations have been planned for full assessment of power recovery.

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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Power Supply Assessment in Derna & Al Bayda (Libya) using Night-time Light Imagery

**UNOSAT code FL20230912LBY, GDACS Id: 1102204** Status: Power outage observed. Further action(s): continue monitoring Based on the estimation from night-time light, power supply of Derna reduced by more than 90% after the floods. As of 24 September 2023, the power supply of Derna has been restored to about 80% of its pre-floods level. As of 19 September 2023, the floods affected areas in Derna were still in blackout. Night-time light within the floods affected areas accounts for 30% of Derna’s total night-time light. Based on the estimation from night-time light, power supply of Al Bayda reduced 60% after the floods. As of 24 Sept. 2023, the power supply of Al Bayda has been restored to 90% of the pre-floods level. After the floods, Derna suffered the most severe power outage. Outer areas of Al Bayda had more power outage than the city center. On 24 September 2023, power supply in most areas of Derna and Al Bayda has recovered to the pre-floods levels.