Wetland River Flow Interaction in a Sedimentary Formation of the White Volta Basin of Ghana

Abstract

Groundwater resources in the floodplain wetlands of the White Volta River basin of Ghana is a major source of water for irrigation activities of communities living around and baseflow to sustain the flow of the river. Hydrology of the floodplain wetlands in the basin is complex, characterized by temporally variable storage volumes with erratic contribution to streamflow. For the continual usage of groundwater resources in the floodplains there is a need to study the form of interaction between the main river and floodplain wetlands. The study, adopted the PM-WIN (MODFLOW) model for simulating the interaction between the wetland and stream. Additionally, the lower boundary discharge output from the HYDRUS-1D model is the estimated recharge. This input quantifies the temporal and spatial variations in sub-surfaces discharges in the floodplain wetland. The simulation of the sub-surface hydraulic head of the wetland indicates a systematic variation relative to the White Volta River response to changes in the rainfall pattern. The interaction conditions vary from season to season with March, April, and May showing the least leakage (estimated values of 0.03 mm/day, 0.06 mm/day, and 0.15 mm/day, respectively) from the river into the floodplain wetland. Notably, the interaction between the wetland and the river as simulated is bidirectional. With most of the flow coming out from the river into the floodplain wetland, this condition persists in the months of August and September.