Participatory Mapping for Historical Flood Inundation Extents

As the neighbourhoods of Ramani Huria have been mapped, it is now possible to start building upon these maps. This can take many forms, but the community is at the heart of how these maps are being used. One approach is participatory mapping, where community members and local government leaders work together to sketch out the extents of historical flood events, drainage systems, ultimately mapping out flood prone areas. By sharing their historical flooding information, it is then possible to more accurately identify at-risk zones and propose temporary evacuation centers.

So far, this participatory mapping approach has been completed in four neighbourhoods in Dar es Salaam: Tandale, Msasani, Mwananyamala and Buguruni. It is relatively simple and low tech – tracing paper, pencils, erasers and the map are the only equipment needed at the community level.

Participatory mapping in Tandale

Participatory mapping in Tandale

To start, the mapping community identify areas which are mostly affected by floods in a basemap. Thereafter they used pencil to map flood prone areas in tracing paper which was set on top of basemap.


The output of the tracing is above. This is then scanned, and the contained data is digitized into shapefiles and uploaded into OSM.


Once this has occurred, it is possible to use tools such as QGIS and InaSafe to prepare flood inundation maps, showing in detail the potential population and exposure of the combined historical flood extents. This information can be used to enhance local response planning and preparedness towards flooding, as communities and disaster managers will have data for an improved understanding of how many and which resources are at risk and the minimum needs to be provided to the affected population. This enables evidence based decisions to be made, while offering a forum for communities and local government leaders to share their stories. Due to the unplanned nature of many of the communities that Ramani Huria works in, haphazard and poorly constructed structures combined with poor drainage systems culminate in a high risk to flooding. With the participatory approach, it’s possible to collect data to form the start of an evidence based decision approach on where to improve infrastructure.

All images sourced from article

Original link