Topic T3 - Aqua 2015 - 42nd IAH Cong
877 - CLIMATE VARIABILITY AND GROUNDWATER STORAGE IN A WEATHERED
CRYSTALLINE
ROCK AQUIFER: EVIDENCE FROM LONG-TERM MONITORING IN THE SOUDANIAN AREA OF
BURKINA FASO
Youssouf Koussoubé
Université de Ouagadougou, Laboratoire d'Hydrogeologie, Ouagadougou, Burkina Faso
Suzanne Yaméogo-Ouandaogo
Université de Ouagadougou, Laboratoire d'Hydrogeologie, Ouagadougou, Burkina Faso
Richard Taylor
University College London, Department of Geography, London, United Kingdom
Guillaume Favreau
IRD, Université de Montpellier, Montpellier, France
Weathered crystalline rock aquifer systems which underlie much of the tropics including 40% of Sub-Saharan
Africa, represent a distributed and potentially climate-resilient source of freshwater. The impacts of climate
variability, land-use change, and abstraction on these low-storage aquifer systems are not well understood,
particularly in semi-arid environments. We review evidence from a multi-decadal chronicle of groundwater levels
in Ouagadougou, Burkina Faso. The chronicle reveals both seasonal responses of low amplitude (~1 m) to
monsoonal rainfall and a longer-term oscillation of greater amplitude (several metres) that can be linked to
decadal
variations in precipitation characterized by the Sahelian Drought. The multi-decadal chronicle at Ouagadougou
demonstrates a strong relationship between groundwater storage and climate variability. Current research seeks
to: (1) estimate the volume of groundwater storage changes by applying storage co-efficients derived from
geophysics (MRS) and lysimetry to borehole hydrographs; (2) evaluate the impact of land-use change and
abstraction on estimated groundwater storage; and (3) assess the impacts of rainfall intensity on groundwater
recharge and abstraction on groundwater discharge that has been enabled by the recent introduction of
highfrequency
(hourly), automated monitoring of groundwater levels.