#847 - Malawi Flood 2015 - Lower Shire (Archived)

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This project was archived.

  • Author: HOT, MapGive
  • Mapping for: Department of Disaster Management Affairs in Malawi - DoDMA , GFDRR
  • Purpose: Crisis Response
  • Priority: High

The Southern parts of Malawi along the Lower Shire river (that connects Lake Malawi and Zambezi River) are frequently flooded and affects the villages of farmers around. Since mid January 2015, they are critically hit (read eg this article).

HOT has been involved in 2014 in a Community Mapping and Training project with the national Department of Disaster Management Affairs in Malawi. DoDMA and GFDRR agreed about the necessity to have detailed data of the region, through a community mapping in the field, that could be used to build hazard impact scenarios with tools like InaSafe in order to improve the planning, preparedness and response activities HOT funded Project. At that time the flood prone area have been identified through local experience and knowledge from DoDMA headquarters, DoDMA districts officers, Heads of Groups of Villages and local people. All the residential areas have been mapped as well as all the buildings and water&sanitation objects.

Since the floods, GFDRR got a "TerraSAR-X/TanDEM-X © 2015 German Aerospace Center (DLR), 2015 Airbus Defense and Space / Infoterra GmbH" imagery, captured 13th Jan 2015, whose analysis shows clearly the flood extent. This extent has been intersected with residential areas from OSM and the output has been with a 50 m buffered. (Note: the blue outline on the map on the right is an automatic buffer created by the Tasking Manager, it does not mean anything, so please do not consider it).

This job aims at adding the missing buildings, that will serve to estimate the number of affected people for each settlement.

WARNING: sometimes the buildings have been created as a node. Please do not delete them as they generally encompass a lot of attributes from the field survey done in August-September 2014.

Imagery Details

When Bing high resolution imagery is not available, the imagery is from Digital Globe’s WorldView-2 satellite, captured on July 20, 2014 and provided by the MapGive project (see below). The images are greater than 50GB in size and have been pan-sharpened (combined panchromatic and multispectral images) for visual clarity and orthorectified for terrain corrected geographic precision. Additionally, the images have been contrast stretched using a custom stretch and processed into a Tiled Map Service (TMS) for performance. The offsets this specific imagery has with the Bing imagery are informed with the JOSM offset_db plug-in. Do not try to correct offsets with Bing Imagery, just use it "as is".


Through the MapGive project, the Humanitarian Information Unit (HIU) of the U.S. Department of State is providing the OpenStreetMap community access to updated satellite imagery services to help assist with humanitarian mapping.

Created by sev_osm - Updated - Priority: medium


Changeset Comment
Malawi, #Malawiflood2015, #MapGive, #hotosm-task-847 Source = WorldView-2, DigitalGlobe, NextView, 20 July 2014 or Bing
When saving your work, please leave the default comment but add what you actually mapped, for example "added buildings and a residential road".

[imagery url available only after accepting the license]

Access to this imagery is limited by the NextView license agreement.

You need to review and acknowledge the agreement.

If you map in an area where there is no high resolution Bing Imagery, then use the WordView-2 imagery provided through this TM job.

Please map:

  • all the buildings should be mapped. Please add a tag building:roof=permanent where the roofs are not made of traditional material (straw): eg all the shinny white or grey ones are actually metal sheet. PLEASE DO CARE THE BUILDINGS HAVE BEEN SOMETIMES MAPPED AS NODES FROM FIELD MAPPING WHAN THE MAPGIVE IMAGERY WAS NOT AVAILABLE. dO NOT DELETE THEM, THEY HAVE A LOT OF ATTRIBUTES

Map if missing:

  • all the residential areas precisely, close to the buildings, without going over the farm lands. You can find an example here.
  • all the roads and tracks. Tag them according to the Highway Tag Africa wiki page. Most roads connecting villages should either be unclassified or tertiary with only occasional small clusters of isolated houses being connected to the road network by a path (only use path if it would be too small to even drive a 4x4 vehicle on).
  • all the waterways (river, stream and irrigation ditches when obvious). Streams and ditches may look like dirt roads like this image (vertical feature is a track road, curvy feature is a dry stream). Verify if the tag is correct.

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