HOT Supporting the Greater Accra Resilient and Integrated Development Project to Protect Communities from Flooding

This article was originally published by Humanitarian OpenStreetMap Team (HOT).

Flooding has plagued the Ghanaian capital of Accra for years, so HOT worked with Mobile Web Ghana and OpenStreetMap Ghana to develop data on local buildings, drainage, and infrastructure that communities and municipal authorities could use to make vulnerable neighborhoods more resilient.

Flooding has been a persistent and even deadly problem for the residents of Accra for years. The Ghanaian capital sees floods during the rainy season every year, and 60% of the city’s population lives in the flood-prone Odaw River basin. In April 2019, 5 people were killed by floods, and in 2015 between a hundred and two hundred people were killed either by floods or by fires while flooding confounded rescue efforts. The floods each year also displace many vulnerable residents, destroy properties, and spread waste, leading to outbreaks of diseases such as cholera.

The Humanitarian OpenStreetMap Team (HOT) teamed up with Mobile Web Ghana and OpenStreetMap Ghana to execute the Open Cities Accra (OCA Accra) project. This project provided Ghana’s Ministry of Inner-Cities and Zongo Development and the Greater Accra Resilient and Integrated Development (GARID) project with vital data to combat these deadly floods and to build the stakeholder’s capabilities to collect and use spatial data to improve the lives of people in the most vulnerable communities.

OCA Accra’s work focused on the under-mapped neighborhoods of Alogboshie, Alajo, Akweteyman, and Nima. These communities lie along the Odaw River and are not only vulnerable to flooding themselves, but are also major sources of waste being swept into the river during floods.

These efforts were funded through The World Bank and took place from June 2018 to February 2020. OCA Accra supported the wider GARID project and Open Cities Africa, a World Bank funded effort to use open data to build sustainable and resilient communities across 15 cities in Africa.

Starting with Remote Mapping

To help the local communities and government tackle the flooding and waste challenges, OCA Accra employed remote mapping, field data collection, and data validation. The project also aimed to build the capacity of the local government and communities to collect and interpret spatial data and contribute to the OpenStreetMap platform even after the project ended.

Satellite imagery on the left and drone imagery on the right

This remote mapping tapped into both local and global networks. The project was primarily supported by OSM community members in Ghana including YouthMappers. As project stakeholders and community members were also trained in mapping, they joined the local OSM community and provided significant help in mapping the neighborhoods, particularly in Alogboshie, Akweteyman, and Nima. Meanwhile, The World Bank hosted a mapathon in Washington, DC to support the mapping of Alajo.

DC mapathon

Moving on to Field Mapping

The mapping based on the satellite and drone imagery set the stage for in-person mapping and photo-taking in the neighborhoods. Whereas the remote mapping had identified roads and building footprints, the field mapping collected data on the building materials and levels, road widths, waterways, drains, potable water sources, waste dumping sites, and essential services like education and health facilities.

For this field mapping, the OCA team recruited local mappers. They were trained in intensive four and five days sessions at Mobile Web Ghana, where they learned how to create and collect geospatial data from imagery and in the field using free and open source software such as JOSM, the Tasking ManagerOpenMapKit, and OpenDataKit.

In addition to the data they collected, these teams of mappers found the effort to be a valuable experience to learn and share new skills. Chris Eshun, one of the mappers, said, “Our field team was diverse, with some experts in OSM and data collection and others completely new to the world of mapping.” Pascalina Awelana Abadum, one of the mappers and data cleaners, wrote that she unraveled her career passion and interest area through her participation in this project.

Field mappers with Open Cities Accra

The field teams mapped and took photos using mobile phones, and the images were then uploaded to Mapillary. These street-level images were an invaluable resource for recording and verifying details about the features they mapped.

Engaging community members
Validating waste data with geotagged images from the field and JOSM

Working with Stakeholders

OCA Accra had a multifaceted approach to stakeholders, in both engagement and goals. In planning the project, the team had hosted stakeholders from numerous institutions including the Accra Metropolitan Assembly, Land Use and Spatial Planning Authority, and Forestry Commission, among many others, and assessed what data resources these organizations had and what data they needed from the field. This assessment led to the project prioritizing flood history and physical infrastructure data so that it would be up-to-date and comprehensive for the government and accessible to the public.

Open Cities Accra Project team meets with the Ministry of Inner City and Zongo Development

Stakeholders were also asked about what data products would be most useful to them, leading to the conclusion that the best way to share the data gathered by the project would be through a web application and wall maps.

Web application

Stakeholders were also taught how to use and contribute to the OpenStreetMap platform, enabling them to continue generating and using data after the project was over.

Impact for the Community

The main results of the Open Cities Accra Project were the data products and the geospatial data made available for free on the OSM platform. Across the four communities, over 8 sq km of dense urban development was mapped, including close to 36,000 buildings and over 98 km of roads and paths.

To better understand flooding in these communities, the field mappers mapped over 1,500 drain points and over 83 km of drain segments. Hundreds of social services were mapped, including schools, clinics, and financial institutions. In addition, hundreds of solid waste dumping sites, potential sources of disease during floods, were also mapped. This data will enable drainage improvements, flood forecasting, solid waste management, and improved urban planning to support these communities.

The OCA Accra team also conducted a public training and exhibition workshop for the stakeholders and community members to showcase the data they had collected. One participant from the Land Use and Spatial Planning Authority reported that his department heavily relies on the OpenStreetMap platform and that data from the project would be essential to the government’s street-naming project. Another participant from the Ministry of Inner-Cities and Zongo Development said the data would be useful for their work to upgrade slum areas to make them resilient to natural hazards.

Mapping infrastructure assets would also aid in mobilizing revenue and generating funds within the Ayawaso East Municipal Assembly (AEMA) area, reported one of their representatives. The AEMA intends on also “using the aerial photo extensively in the property addressing exercise we will be embarking on very soon,” reported Jamila Salihu, an Assistant Physical Planning Officer with the AEMA.

Engaging stakeholders

In addition to the direct impact of the data generated, the OCA Accra project also developed the capacity of local agencies and community members to generate and use spatial data and contribute to OpenStreetMap. Over the course of the project, OCA trained over 110 mappers and 30 staff members of government institutions in contributing to OpenStreetMap, adding to the growing community of Ghanaian OpenStreetMap contributors.