WACA-VAR

West African Coastal Areas- Mapping Vulnerability, Adaptation and Resilience in a changing climate

Overview

WACA-VAR emerged from the observation that data and knowledge on the dynamics of Africa's coasts are insufficient, despite the fact that the West African coast is particularly threatened by climate change. This interdisciplinary project brings together international scientific leaders and coastal adaptation experts specializing in the impacts of climate change in West Africa. Through 3 modules, it has 2 objectives:

• Produce new data from satellite imagery to better characterize coastal ecosystems;
• disseminate the results via a web-GIS platform to support public policy decision-making by coastal managers.

The project will produce regional geodata useful for planning infrastructure projects. It will focus on the themes of marine submersion, erosion and building resilience.

Coastal erosion from space (in French) © IRD

Methodology

Work package 1 will develop hydrodynamic and morphological data on the evolution of the coastal zone and other coastal factors derived from satellite data, including a coastal vulnerability index.

Work package 2 will aim to develop a regional vulnerability index for socio-ecosystems based on satellite data, and to specify the ranges of validity for using satellite data for the design (engineering) of coastal protection solutions.

Module 3 will focus on communication and dissemination via a web-based GIS interface, workshops, press releases and scientific publications.

Consortium

The project is supported by IRD and LEGOS. IRD, Development Research Institute, is a French scientific research and international cooperation organization focusing on sustainable development issues. LEGOS, Space Geophysics and Oceanography Laboratory (Laboratoire d'Etudes en Géophysique et Océanographie Spatiales), specializes in the study of Earth sciences, oceanography and geophysics using data collected from space observations, notably by satellite. LEGOS researchers conduct interdisciplinary research to understand the processes that shape our planet, with a particular focus on the oceans, climate, land-atmosphere interactions and ecosystems. LEGOS is supervised by CNES, which is also funding the project, the CNRS, the University of Toulouse and IRD.

Egis, an international player in consultancy, construction engineering and services for mobility and sustainable cities, is also involved. In the coastal field, Egis carries out diagnostics of systems (erosion, marine submersion, pollution) and structures, hydro-sedimentary modelling, designs protection structures and innovative and sustainable infrastructures at sea (eco-reefs, sustainable ports, etc.) and supports its partners in planning for greater resilience of territories and preserved or restored coastal ecosystems.

The Ecological Monitoring Centre (CSE, Centre de Suivi Ecologique) in Senegal (West African Coastal Observatory) and the University of Cape Coast in Ghana are also participating as users of the system developed.

WACA-VAR is an essential component in the production of complementary knowledge for WACA, the West Africa Coastal Areas Program, a World Bank programme for the management of the West African coastline, an important pillar of which is the West African Regional Coastal Observatory (ORLOA, Observatoire Regional Ouest Africain du littoral), coordinated by the Ecological Monitoring Centre in Senegal.

Application site(s)

The work will be carried out both at the scale of the entire West African coast, from Mauritania to Cameroon, and at the scale of two specific study sites: Saint-Louis in Senegal, and Dansoman in Ghana, where subtidal sea level data will be generated.

Data

Satellite

• Sentinel-2
• Pleiades
• VENµS

Other

• In situ measurements (drone, field surveys)

Results – Final product(s)

Using state-of-the-art satellite imagery processing methods, the data produced as part of this project will consist of maps of the issues, coastal environments, associated bathymetry and topography, and hydrodynamic parameters (waves, water levels). In the first phase, this high-precision data derived from the latest developments (data processing) and satellite sensors, together with validation data acquired on site, will be produced and made available to the project's stakeholders and partners.

During the second phase of the study, these satellite and in-situ data will be processed and coastal vulnerability indicators will be derived to better characterise the impact of climate change on West African coasts. The range of validity of the satellite products will be discussed for use in the identification and sizing phases of risk management solutions (e.g. construction of dykes, sand recharging, ecological engineering solutions, relocation of issues).

Finally, the data and associated indicators will be disseminated through the construction of a WebSIG platform open to all (data can be consulted and downloaded).

The main methodologies developed and the results will be published, targeting scientific journals, and presented to site managers and local stakeholders (in particular members of the Observatory and coastal managers from the WACA programme) at feedback and communication workshops.

👉 Creation of the website for the WACA-Var programme in 2024: https://wacavar.net/

References

• Dada, O.A., Almar, R. & Morand, P. Coastal vulnerability assessment of the West African coast to flooding and erosion. Sci Rep 14, 890 (2024)

• Alves, B., Angnuureng, D. B., Morand, P., & Almar, R. (2020). A review on coastal erosion and flooding risks and best management practices in West Africa: what has been done and should be done. Journal of Coastal Conservation, 24, 1-22.

• Almar, R., Stieglitz, T., Addo, K. A., Ba, K., Ondoa, G. A., Bergsma, E. W., ... & Arino, O. (2023). Coastal zone changes in West Africa: challenges and opportunities for satellite earth observations. Surveys in Geophysics, 44(1), 249-275.

• Dada, O., Almar, R., Morand, P., & Ménard, F. (2021). Towards West African coastal social-ecosystems sustainability: Interdisciplinary approaches. Ocean & Coastal Management, 211, 105746

• Dada, O. A., Almar, R., Morand, P., Bergsma, E. W., Angnuureng, D. B., & Minderhoud, P. S. (2023). Future socioeconomic development along the West African coast forms a larger hazard than sea level rise. Communications Earth & Environment, 4(1), 150.

• Giardino A., van der Spek A., Schrijvershof R., Nederhoff K., de Vroeg H., Briere C., Tonnon P.K., Caires S., Walstra D.J., Sosa J., van Verseveld W., Schellekens J., Sloff K., (2018). A Quantitative Assessment of Human Interventions and Climate Change on the West African Sediment Budget, Ocean and Coastal Management, Volume 156, 15 April 2018, Pages 249-265.

Related project(s)

SCO OSS Saint-Louis: this project presents complementary methodological objectives for the Saint Louis site in Senegal, with the possibility of scaling up to the West African region as part of WACA-VAR.

SCO ALISE: the platform developed by this project will complement the WACA program.

Project news

17/01/2024: WACA-VAR : two workshops and a publication