This map illustrates potenital satellite-detected inundated areas and water in and north of Sar-E Pol city, Afghanistan. UNOSAT analyzed imagery from the Pleiades satellite collected 1 May 2014 in response to heavy rainfall occurring on 23-24 April 2014. UNOSAT extracted areas of water and inundated soils to indicate likely flood affected lands. This map includes both permanent water bodies, such as streams, and potential flood waters together due to limitations in source data. It is likely that flood waters and inundation have been systematically underestimated along highly vegetated areas and within built-up urban areas because of the special characteristics of the satellite data used. This analysis has not yet been validated in the field. Please send ground feedback to UNITAR /UNOSAT.
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.
Caveats / Comments
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 firstname.lastname@example.org to seek clarification.