#2480 - Missing Maps - Ngao District, Kenya - Water and Habitat project - Step 2 (Archived)

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This project was archived.

Advanced contributors only: imagery interpretation difficult

  • Author : Missing Maps / CartONG
  • Requesting Organization : ICRC
  • Priority : Medium
  • Imagery : Digital Globe and MapBox

The inhabitants of Ngao continually experience safe and clean water access issues for both personal and animal use, during the dry seasons because of droughts, or rainy season because of flooding. Crocodiles attacks on people and on livestock make it even harder. On top of that farmers and nomadic people are constantly in conflict as nomadic people trespass farmers farmlands, destroying their crops.

The Ngao water network currently serves about 15,000 residents and institutions including schools, hospitals and government institutions which cover 8 villages.

This mapping project will help the ICRC Water and Habitat team working on the extension of the already existing pipeline and the construction of cattle troughs at strategic positions. This aims at increasing the number of residents accessing safe and clean water by around 2’000 residents. The goals is also to reduce vandalism by pastoralists seeking alternative water sources. Eventually the plan is to drill a borehole or increase the water treatment plant capacity to match up water supply to the demand.

You'll find pictures from the project here

The Missing Maps project aims to map the most vulnerable places in the world (affected by humanitarian crises: disease epidemics, conflict, natural disasters, poverty, environmental crises). Building on HOT's disaster preparedness projects, the Missing Maps tasks facilitate pre-emptive mapping of priority countries to better facilitate disaster response, medical activities and resource allocation when crises occur.

Created by Violaine_Do - Updated - Priority: medium


Entities to Map
road network, buildings, plantations, waterways, settlements
Changeset Comment
#hotosm-project-2480 #ICRC #ICRC-Ngao #PH #MissingMaps source=DigitalGlobe NextView composite image 0070415-040615-210216
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.

This area is divided into 2 different projects (2483 and 2480), respectively on buildings/roads, and landuse/water area.

The aim is to facilitate the work of new mappers as well as improve the quality of tracing.

For this second step of tracing, please map only the water and landuse data.

Do not map buildings and roads, else it will create massive conflict errors with the other steps when saving your job.

Don't hesitate to mark tasks as done if they are complete, even if you didn't have to map anything on it!


For this project, we will use:

  1. Mainly use the Digital Globe imagery: more up-to-date, and easier to map with (in color). This imagery is taken during the dry season.
  2. In location where you don't have DG imagery, or with cloud cover you should change to MapBox imagery. This imagery is taken during the wet season.

To change the imagery:

  • In the ID editor: use “Background settings” (shortcut, “B” key) and switch between “Custom” (Digital Globe) and “Mapbox satellite imagery”

  • In JOSM: add Digital Globe using the menu “Imagery/Imagery Preferences”, click the “+TMS” button in the lower right. Copy-and-paste the link shown above, enter “Ngao, Kenya” and validate. Then alternate the imagery using the Layers menu (clicking the “eye” image or the “Activate the selected layer” button )

Digital Globe is providing ortho-rectified imagery to improve geographic precision and then enhanced. This imagery is made available via a Tiled Mapping Service (TMS) to improve performance.


Be careful : the main difficulty about this project is understanding the true location of waterways

Please only map waterways as shown on DG imagery i.e. as it should be during the dry season. You will notice a difference of water area between DG (dry season) and Mapbox (wet season) imagery due to the date of capture. Which means that rice fields need to be mapped as so, and not as water area when it is flooded as we can see in MapBox imagery.

2 different cases for mapping river :

  1. If it is a tiny river please use waterway=river
  2. If it is a large river please use waterway=river for mapping the thalweg (deepest point of water, in the middle of the river) in addition to the tag waterway=riverbank (banks of the river)

For more information please refer to the wiki page : http://wiki.openstreetmap.org/wiki/Tag:waterway%3Driverbank


Please use the tag landuse = farmland

If you know the culture type, please add it with the key crop. For instance if the farmland is a rice field please add the tag crop=rice.

More information about possible crop tags here : http://wiki.openstreetmap.org/wiki/Key:crop


Please use the appropriate tag, either natural= scrub or natural=heat

For more information please see: http://wiki.openstreetmap.org/wiki/Key:natural

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