Toward a new approach for hydrological modeling: a tool for sustainable development in a savanna agro-system

Agriculture in Tambarga, a small, remote village in the landlocked country of Burkina Faso, is dependent on the seasonally variable local hydrology. Extreme seasonal and spatial variability of rainfall significantly impacts the livelihood of farmers, who depend mainly on rainfed agriculture. This dependence on rainfed production makes them particularly vulnerable to meteorological conditions, and they continually experience food insecurity. The groundwater is promising as storage to mitigate effects of drought. However, because of its interaction with the various hydrological components, we need to better understand all the processes to fully assess the impacts of possible solutions. Hydrological and meteorological data were collected over a two-and-a-half-year period in the catchment adjacent to the village (area = 3.5 km²) to address these issues. The field studies show that the major portion of storm runoff was generated in the upper savanna basin, while baseflow appears to be mostly originating from the downstream agricultural field. The seasonal cycle of groundwater appears to control the stream flow and therefore, the continuous flow over the entire stream occurred when the water tables became interconnected and surfaced the ground level. Additionally, this paper discusses water management scenarios (open dam, deeper wells and buried dam) for agricultural purposes using a simple and comprehensive hydrological model. Simulations based on reducing evaporation rate by keeping the water underground present a solution that could improve agricultural production, and therefore, reduce vulnerability of Tambarga’s farmers to climate change.