Review of Isotope Hydrology Investigations on Aquifers of Cameroon (Central Africa): What Information for the Sustainable Management of Groundwater Resources?

In Central Africa, groundwater remains the least understood component of the water cycle. Isotopic techniques that are well known to be efficient in tracking the movement of water along its path have been applied for only three decades and can be summarized in a handful of case studies. This review aims to put together all the stable and radioactive isotopic data (>500 samples from rainfall, surface and groundwater) published in Cameroon to: (i) identify the drivers responsible for precipitation isotopes' spatial variation and climatological implications, (ii) elucidate the groundwater recharge mechanisms over the countries and relationships with rivers, and (iii) highlight the existence of paleo-groundwater in the country. It is found that rainfall stable isotope variation is linked to the migration of the Intertropical Convergence Zone (ITCZ): the groundwater recharge can be diffuse and focused. This latter mechanism is mainly observed in the semi-arid region. It is in this relatively dry region that most of the paleo-groundwater resources are identified thanks to C-14 dating. This information will be useful to develop water management strategies regarding all the challenges (e.g., climatic and demographic) faced by the country. Finally, this paper discusses the gaps groundwater isotope hydrology can still fill for contributing to a sustainable development of the country.