Department of Geology and Geological Engineering Van Tuyl Lecture Series- Fall 2015 4:00-5:00 p.m. in Berthoud Hall Room 241    Thursday, December 10, 2015 Jean-Martial Cohard Joseph-Fourier University-Grenoble, France   “West Africa: a Hot Spot for Hydrological Global Change Impacts”   Abstract: West Africa is one of the regions in the world the most vulnerable to face climate changes, especially for Water resources, with the highest demographic rate in the world (3% per year) and still insufficient access to drinkable water. More over, climate change impacts over West Africa remain the most uncertain for IPCC scenario. In this context, the hydro-meteorological AMMA-CATCH Observatory, based on 3 meso-site along a latitudinal transect has been designed to monitor hydrological changes. At regional scale, intensification of the hydrological cycle has already been identified through more intense thunder storms, longer dry periods. The combination of this intensification together with land use changes has led to water table level increase, the sahelian paradox, and recent dramatic floods in big sahelian cities. At mesoscale our team focuses mainly on sudanian climate where hydrology develops over a complex hard-rock basement zone. The large instrumentation network deployed over the Oueme catchment critical zone observatory allows characterizing hydrological processes with cluster logic. It is shown that aquifers are mainly drained through evapotranspiration. In consequence, changes in rainfall regime and land use distribution have a direct impact both on evapotranspiration regime and then on aquifer storage and river discharge. However, for both sahelian and sudanian regions the question of the attribution of global changes for river discharge is still an open question.