Centre Européen
de Recherche et d'Enseignement
des Géosciences de l'Environnement

Water Cycle and Paleohydrology

 

To assess the resilience and vulnerability of eco-hydrosystems, the team strives to constrain the critical control values and potential feedbacks between forcings and responses of current and past systems, in continental and marine environments.

The team deciphers the fine interactions between current climate variability and ecosystems. For example, the analysis of the interaction between climate dynamics from the diurnal to the interannual scale and the dynamics of the Congo Basin forest is envisaged. It is also planned to work on increasing the predictability of tropical rainfall (Caribbean, India, Indonesia, Africa) (LMI DYCOFAC project).

In order to address this theme over the long term, it is important to continue the implementation of integrated approaches establishing a temporal continuum between the climate processes observed today and the sedimentary records of the past. In the continental environment, the monitoring and sampling of instrumented watersheds of lake systems by CEREGE (Cameroon, Ethiopia, Morocco, Tanzania, Chad) should be expanded in order to propose "observatory zones" with the support of national and international programs (MISTRALS-Paleomex, ICDP, IRD Observatory). The team also participates in several international consortia with the objective of reconstructing the modifications undergone by eco-hydrosystems during the last millions of years, e.g. in East Africa (Lake Tanganyika, ICDP application in progress, collaboration with the universities of Basel and Arizona). These projects are supported by a strong expertise in the use of hydro-biogeochemical and isotopic approaches and proxy development, capable of proposing quantitative reconstructions of water cycle variations. This expertise translates into reconstructions of precipitation regimes (pollens), local water balances (lake levels from diatoms; coupled diatom/ostracode stable isotopes). A priority of the team is the innovative development of a proxy of past continental humidity, a key parameter of the water cycle and the climate system. Holocene reconstructions are planned in West Africa (ANR project HUMI-17). The analysis of various organic compounds, e.g. GDGTs, in lake, estuarine and coastal sediments is in progress in order to reconstruct regional hydrological conditions and their influences on lake and river systems (e.g. BNP Colonia Project 2017-2019, local PI E. Bard). This theme is completed by the study of ocean/continent connections via the geochemical characterization (quantity, nature, source) of detrital marine sediments which could allow us to propose erosion and atmospheric circulation proxies in relation to climate changes on the continent (Paleomex/MISTRALS).

These approaches take place within the framework of concerted collaboration with the RRH team, especially for the axis "Tracing and quantification of flows at interfaces", which allows to optimize the integration of physico-chemical, hydro-biogeochemical data, the modeling of interactions and feedbacks to climate change.