Mapping the socio-physical dynamics of the Western Indian Ocean deltas

WIOMSA 12th symposium, poster presentation, October 11th, 2-3pm

THEME VII Estuaries and their resources 

View of the Tana Delta @ IRD - Stéphanie Duvail


Paolo Paron, IHE-Delft,

Stéphanie Duvail, UMR PALOC, IRD,

Dominique Hervé, UMR SENS, IRD,

Dinis Juizo, University Eduardo Mondlane,

Nordino Paluluane, University Eduardo Mondlane,

Simon Mwansasu, University of Dar Es Salaam,

Peter Gitau, UMR PALOC, Museum National d’Histoire Naturelle, Sorbonne Université,

Wanja Nyingi, National Museums of Kenya,

Johary Andriambeloson, IOGA (Institut Observatoire Géophysique Antananarivo)

Eric Delaitre, UMR Espace-Dev, IRD,

Laurent Robison, CNRE (Centre National de Recherche sur l'Environnement),

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The deltas of the Western Indian Ocean are dynamic waterscapes built by rivers with steep headwater gradients and high sediment loads meeting a strong tide Ocean. This dynamic is affected by climate change, land-use changes and dam construction, with impact on the livelihoods of the delta users. 

We present the output of a research combining field observations, expert knowledge and remote sensing based on Google Earth Engine. It aims at the identification of the rates of socio-ecological changes and analysis of their main drivers for the past 35 years, in four Western Indian Ocean River Catchments and Deltas:

  • Tana River in Kenya
  • Rufiji River in Tanzania
  • Incomati River in Mozambique
  • Betsiboka River in Madagascar

We highlight the similarities in the physical environment and, where possible, also in the socio-economic-political environments that are driving the current changes, potentially affecting resilience of the local population and their sustainable development potential.

We focus on the substantial changes in the following aspects: precipitation seasonality, flooding patterns and frequency, land cover, dry forest cover, mangrove cover, crop production area, fish population, human population, human migration flow, frequency of human conflicts within the delta population. The observed changes call for reflection given the IPCC climate change predictions.

Mapping workshop, Mozambique 2021@ Stéphanie Duvail

These findings are a set of preliminary results of the collaborative and multidisciplinary effort produced within the GDRI-Sud network DELTAS and within the DIDEM project that brought together several research institutions from The Western Indian Ocean and Europe (The National Museum of Kenya, University of Dar Es Salaam in Tanzania, University Eduardo Mondlane in Mozambique, Centre National de Recherches sur l'Environnement in Madagascar, IHE Delft in the Netherlands, Institut de Recherche pour le Développement in France) for a collective mapping exercise.

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This work was done in the frame of the WIODER network