Suppressed Convective Rainfall by Agricultural Expansion in southeastern Burkina Faso

English Abstract:

With the ‘green economy’ being promoted as a path to sustainable development and food security within the African continent, the conversion to agricultural land is proliferating at a rapid pace often replacing natural savannah forests. Where agriculture is primarily rain-fed, the possible adverse impacts of agricultural land influx on rainfall occurrences in water- limited areas such as West Africa are investigated. . Using field observations complemented by model calculations in southeastern Burkina Faso, the observation of a 10-30% suppressed rainfall recorded over agricultural fields when referenced to natural savannah forests are explained. Measurements and simulations reveal that the crossing of the mixed layer height and lifting condensation levels, a necessary condition for cloud formation and subsequent rainfall occurrence, was 30% more frequent above the natural savannah forest. This increase in crossing statistics was primarily explained by a larger sensible heat flux above the savannah forest rather than differences in lifting condensation heights.