Debrief conducted by Sam Colchester (HOT) partner engagement lead for this activation.

Relevant statistics

In total 171 contributors made over 125,000 edits to OSM including mapping over 96,000 buildings as part of this campaign. (See ohsomeNow Stats page for tracking overall contributions)

Nigeria Floods 2024 daily contributors

Narrative summary

Shortly after the severe flood event in Nigeria on Tuesday 10 September 2024 the director of the Open Mapping Hub - West and Northern Africa requested support from HOT’s central team to respond.

On Thursday, 12 September a size-up was completed by Pete Masters (HOT) and a search for affected areas revealed a UNOSAT flooded area polygon for Maiduguri. The extent of this polygon was manually digitised from a georeferenced screenshot because UNOSAT’s download did not include the Maiduguri flood extent in a spatial file format. MSF staff flagged to HOT that OSM road and building features would be important to their operations in Maiduguri. HOT conducted a manual visual check of Maiduguri, revealing that most buildings were not digitised in OSM but that the road network was fairly well mapped.

Search for existing Tasking Manager projects

On Friday, 13 September, HOT compiled a list of relevant active or completed Tasking Manager projects near Maiduguri and added the extents to a uMap for ease of sharing. The most relevant project that this revealed was a partially complete MSF Tasking Manager project for mapping buildings in western Maiduguri. It happened to intersect the UNOSAT flooded area and so was bumped up to ‘Urgent’ priority by HOT (it initially had a different focus and was about 50% mapped and 25% validated). HOT defined a ‘Priority area’ in the eastern section of this project using the manually digitised UNOSAT flooded extent. This was done in close contact with MSF.

An unfinished and relatively new (published 4 September) roads and buildings Tasking Manager project from Nigerian organisation Geohazards Risk Mapping Initiative in a settlement 80km east of Maiduguri called Dikwa was also identified. HOT contacted the project creator to notify them of the activation and ask if they had plans for further project creation. Before contact the project had already been bumped to ‘Urgent’ priority and subsequently made very fast progress. After nearing completion the following day the project creator lowered the project priority to ‘Medium’ and notified HOT that they did this so that mapping in Maiduguri city could be prioritised.

Establishing new areas of interest and prioritization

On Friday, 13 September, Nigerian Red Cross shared that OSM roads and buildings in Maiduguri would be crucial for their planning and relief operations and provided a list of priority locations. This was in the form of a list of location names, including point locations and the names of Wards in Maiduguri. Local organisation Humanitarian Mappers also shared a shortlist of priority point locations in Maiduguri with coordinates. The Nigerian Red Cross locations were manually geocoded over the next two or three days, and combined with the Humanitarian Mappers priority points in a collaborative uMap for ease of sharing. Several Nigerian Red Cross location names could not be matched against available location names online and therefore were not geocoded.

On Tuesday, 17 September HOT published the first dedicated project in HOT’s Tasking Manager focusing on mapping buildings in Gwange 1 Ward in Maiduguri. This project area was chosen using the ‘Tasking Manager project prioritization’ process outlined in the Wiki (which used the collaborative uMap containing priority locations shared by Nigerian Red Cross and Humanitarian Mappers). Pete Masters notified the wider public of this first dedicated project by posting in the OSM Community Forum. Over the following weeks a further seven Wards were prioritized for mapping using the prioritization process, with a dedicated project for each.

Areas marked red were fully mapped and validated in Tasking Manager by the end of the activation (see UMap here)

A risk assessment for mapping activities in Maiduguri was started on Tuesday, 17 September and fully completed with feedback from local partners on Wednesday, 2 October 2024. Due to there being ongoing violence in the area being mapped the results of the risk assessment included mitigations to minimize risk, particularly on how mapping activities would be documented and publicly communicated.

On Friday, 20 September the priority area in MSF’s Maiduguri project was adjusted to focus on all the areas where the project intersected priority points shared by Nigerian Red Cross and Humanitarian Mappers. Three days later this project was shifted from Urgent down to High priority because all of the priority areas in it were fully mapped and validated.

On Sunday, 29 September Nigerian Red Cross shared several additional priority Wards in Maiduguri and these were used to re-prioritize Tasking Manager project ordering and to create new project boundaries.

On Wednesday 9 October, Maxar released up-to-date imagery under CC-NC license for impacted areas in Nigeria through the Maxar Open Data Programme. This was in response to a request that HOT had made for pre-flood images from Maxar’s catalogue on Sunday, 15 September. After adding this Maxar imagery to OpenAerialMap it was discovered to be identical to the Esri World Imagery which had been used on all projects up to that time.

Closure

By the start of November 2024 nine Nigeria Flood projects had been completed and project progress had started to trail off after the slowdown in news. Accordingly, HOT contacted Nigerian Red Cross to suggest that the disaster response mapping phase should be considered complete. On Thursday, 21 November 2024 Nigerian Red Cross confirmed that they considered the disaster response mapping complete and passed on thanks for the incredible work from the OSM community.

In mid-November 2024 a third-pass validation (final wide-area check) of the MSF Maiduguri project was commenced.

Successes, issues and lessons learnt

[SUCCESSES] What went well?

• Clear coordination between central and hub team (West and Northern Africa) - HOT internal
• Collaboration with partners throughout (launching activation, defining and revisiting priorities)
• Openness on project prioritization allowed outside input (uMap and process documented in Wiki)
• Good quality tasking manager projects (right small size)
• Quick validation progress
• Project closure, no partially completed projects by end of campaign

[ISSUES] What could have gone better?

• Time lost georeferencing and manually digitizing flood extent from UNOSAT
• Received priority locations in non-spatial format and time was lost manually geocoding (and some could not be geocoded)
• Priority locations had no indication of their relative priority, this made prioritization process difficult
• Maxar request was not worthwhile because Esri World Imagery had latest Maxar scenes
• Better understanding how the data was being used would speed up mapping and help HOT to faster adapt to responders’

[SUGGESTIONS] What lessons should influence how we activate in future?

• Encourage community/organizations sharing priority locations to indicate their relative priority (e.g. see ‘Prioridad’/’Priority’ column in this table)
• Always check the Esri Imagery Date Finder before making a request from Maxar for up-to-date imagery — it may already be on Esri World Imagery!
• Encourage community/organizations to share priority locations in spatial format to reduce geocoding workload and reduce chance of miscommunication

Follow up

If you have questions and / or comments related to the activation or this documentation, please contact Sam Colchester at HOT or comment on this diary. For completeness this After Action Review has also been added to the Nigeria Floods 2024 OSM Wiki.