PhD defence

Peter Ng’ang’a Gitau

for the grade of Doctor in Geography of the National Museum of Natural History (ED 227, Paris, France), on the 18th of January 2023.

Environmental dynamics of the Tana River delta (Kenya) at multiple time scales: evidence from geomorphology, mangrove assessment, paleoecology and consequences for landscape management


Abstract

Deltas are productive and biodiversity rich ecosystems but also vulnerable to sea-level rise and human alterations of river hydrology. In order to study the dynamics of the Tana River delta in Kenya, we implemented a multi-disciplinary approach: Sediment coring, geochemical analysis, pollen and macrofossils, geomorphological studies came in support of the understanding of the landscape dynamics.

Our results indicate that since the mid Holocene (5500 BP), the delta has evolved from a mangrove ecosystem to the current woody floodplain, as a response to sea level fluctuation, hydrological changes and human alterations. Over the past two centuries, the Tana River has changed its course 3 times. We highlight the increasing vulnerability of the Tana River delta under present sea level rise and continued upstream river alteration. We suggest that management of the delta should take into account the dynamic nature of the landscape and adopt climate change adaptation measures co-constructed between local population, scientists and decision-makers.

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Jury

  • Prof. Anthony Edward, University Professor, UMR CEREGE, Aix-Marseille University (President)
  • Dr. Guillaud Dominique, IRD Director of research, UMR PALOC, IRD-MNHN (PhD Director)
  • Dr. Duvail Stéphanie, IRD Director of research, UMR PALOC, IRD-MNHN (Co-Supervisor)
  • Prof. Verschuren, Dirk, University Professor, Ghent University, (Co-Supervisor)
  • Dr. Nyingi, Wanja, Senior Researcher, National Museums of Kenya, (Rapporteur)
  • Dr. Paron, Paolo, Senior Researcher, Institute of Water Education, (Rapporteur)
  • Dr. Rucina, Stephen, Senior Researcher, National Museums of Kenya, (Examiner)


Date and location

The defence took place at the French Institute of Research in Africa (IFRA-Nairobi), Laikipia Road, Kileleswha, Nairobi, on January 18th 2023 from 2 PM to 5 PM (East African time) = 12 AM to 3 PM (Paris).