Multiple Conceptual Model Approach for Assessing Groundwater Resources Sustainability Under Multiple Stresses

Six transient numerical groundwater flow models have been developed and calibrated based on six equally plausible conceptual models of the hydrogeological framework of Akyem and surrounding areas in southern Ghana, for the purpose of assessing the impacts of multiple stresses on groundwater resources sustainability in the area. The six conceptual models were developed to account for possible uncertainties in model predictions arising from uncertainties in the model structure and differ in terms of the characterization of domain boundaries and vertical stratification. The domain was conceptualized based on available data monitored over a 48-month period, from 41 boreholes in the area. Data from the 6 models were used to assess groundwater budget trends over the transient period to provide an indication of the state and sustainability of the resource under prevailing conditions in the area. All 6 models agree in terms of the trend in the variations of the key budget components and suggest that the resource is under threat due to the combined impacts of climate change and anthropogenic activities in the area. In decision-making processes regarding groundwater resources fortunes in a complex terrain it is strongly recommended that multiple numerical models, derived from multiple conceptual models, are developed to account for uncertainties associated with the definition and characterization of boundary conditions. This enhances confidence in the results of the modeling enterprise and facilitates.