Satellite Detected Surface Waters Extent and Evolution in Northern Quang Binh Province

Name: Satellite Detected Surface Waters Extent and Evolution in Northern Quang Binh Province
Creator: United Nations Satellite Centre (UNOSAT)
License: http://www.opendefinition.org/licenses/cc-by-sa

✦ DISCOVERED BY ORIONAIUnited Nations Satellite Centre (UNOSAT)Imagery and land coverViet Nam

Viet Nam

About this dataset

This map illustrates the satellite-detected surface waters extent and evolution in north of Quang Binh Province, Vietnam, as observed from the Sentinel-1 images acquired on 12 and 24 October 2016. Within the analysed area, an increase of surface waters extent was observed from the 24 October 2016 image: ~4,400 ha of surface water were observed the 12 October 2016 and reached ~6,400 ha the 24 October 2016. All over the analysed zone, it corresponds to an evolution of about 45%. As example, in Tien Lang lake and dam an increase of water surface of 77 ha was observed corresponding to an evolution of ~70% by comparison to the water surface detected on 12 October 2016. 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 Surface Waters Extent and Evolution in Quang Nam Province

This map illustrates the satellite-detected surface waters extent and evolution in Central and Eastern Quang Nam Province, Vietnam, as observed from the Sentinel-1 images acquired on 07 November 2016 and 01 December 2016. Within the analysed zones representing 75% of the total province area, an increase of surface waters extent was observed between the 07 November 2016 and 01 December 2016. ~26,200 ha of surface water were observed the 07 November 2016 and reached ~39,000 ha the 01 December 2016. All over the analysed area, it corresponds to an evolution of about 50 % : Thang Binh District (+5,300 ha), Nui Thanh District (+2,800 ha), Tam Ky Township (+1,530 ha) and Phu Ninh District (+1,140 ha). This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR - UNOSAT.