Flood Analysis in Pakistan Based on Time Series of Satellite Data Recorded from 28 July to 16 September 2010

Sat, 18 Sep 2010 22:10:25 GMT
Product ID: 1506 - English
Published: 19 Sep, 2010
GLIDE: FL-2010-000141-PAK
FootPrint (Lat x Long, WSG84 Geographic, decimal degrees)
TopLeft: 35.614 x 64.878
BottomRight: 23.74 x 74.448

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ANALYSIS SUMMARY:
This map presents a comprehensive overview of the maximum flood water extent across the affected provinces in Pakistan as detected by a constellation of satellite sensors throughout the course of this catastrophic disaster from 28 July to 16 September 2010. Flood waters depicted on the map have been symbolized with two classes, the first and primary class (shown in red), represents the maximum water extent across the affected provinces, as identified with a very high degree of confidence; the second class (shown in orange), represents potential flood waters which were identified with a moderate to low degree of confidence. Inset satellite images over selected locations across the affected region provide detailed examples of the type of damages and other flood related issues that will need to be addressed during the early recovery and reconstruction phases. Further, a spatial analysis conducted with satellite-derived flood data provided a preliminary estimate of the potential number of villages, towns, infrastructure sites as well as the length of roads and railway tracks directly affected by the flooding. These results have been quantified by administrative province (see included table). Across the whole of the flood affected region, it has been estimated that over 7,490 villages, 135 towns/cities and 190 health facilities were identified as potentially directly affected by the flood waters, the majority of villages completely inundated or surrounded by flood waters without open land evacuation routes. Over 5,000 km of primary or secondary roads were likely submerged along with 400 km of railway tracks and 400 bridges. Please note that the numbers of affected locations presented in this map and associated table likely represent absolute minimum estimates for the area assessed; because of limitations in available settlement and transportation datasets it is certain that the numbers of affected villages, towns and affected infrastructure / transportation lines are significantly underestimated. This disaster analysis was conducted with satellite imagery provided through the International Space Charter as well as from ESA, NASA and USGS.
CALCULATING THE MAXIMUM FLOOD EXTENT
The estimated total surface area of all satellite-detected flood waters during this event was 37,280km2 based on cumulative analysis from 28 July to 16 September 2010. This estimate includes both water classes shown in the map and has been controlled for the normal, pre-crisis water extent of major rivers, lakes and reservoir water bodies using the best available hydrological datasets. Because of the limited duration of the reported flash floods in the northern provinces of Pakistan (especially Khyber Pakhtunkhwa), as well as limitations of the satellite sensors used for this analysis, it is likely that the total extent of flood waters have been underestimated by potentially upwards of several hundred square kilometres. Nevertheless, the total impact of this probable underestimation is essentially negligible when calculating the overall accuracy and completeness of the flood water.
Satellite Data (1): ENVISAT ASAR IMP (HH)
Resolution: 24 meters
Image Dates: 1, 3, 6 September 2010
Source: European Space Agency (ESA)
Satellite Data (2): ALOS PALSAR (FBD & WB1)
Resolution: 25/100 meters
Image Date: 4 July & 5, 19 & 21 August 2010
Source: © JAXA, METI
Crisis Satellite Data (3): RADARSAT-2
Resolution: 25 meters
Image Date: 5, 10, 21 August 2010
Copyright: Radarsat-2 © MDA 2010
Source: Canadian Space Agency
Satellite Data (4): UK DMC2
Resolution: 32 meters
Image Date: 19 August 2010
Source: DMC International Imaging Ltd.
Crisis Satellite Data (5): Worldview-1
Resolution: 0.5m
Image Date: 2 August 2010
Source: USGS, Digital Globe
Crisis Satellite Data (6): QuickBird2
Resolution: 0.6m
Image Date: 14, 16, 24 & 29 August 2010
Source: USGS, GEOEYE
Crisis Satellite Data (7): GeoEye-1
Resolution: 0.5m
Image Date: 5 & 10 August 2010
Source: USGS, GEOEYE
Crisis Satellite Data: MODIS Aqua & Terra
Resolution: 250 meters
Image Dates: 28 July - 16 September 2010
Source: NASA Rapid Response
Landsat-7 imagery: ESRI WMS
Elevation Data: Aster GDEM
Source: METI & NASA 2009
GIS Data : NGA, OCHA, USGS
Transport Data: Google Map Maker
Transport Data Copyright:
© 2009 Google - Improve with Google Map Maker
Refugee Data: UNHCR
Hospital Data: WHO
Flood Analysis: UNITAR / UNOSAT
Map Production: UNITAR / UNOSAT
Projection: UTM Zone 42N
Datum: WGS-84