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

Abstract

Abstract 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. Each of the calibrated numerical models was used to assess the impacts of enhanced groundwater abstraction attending population growth, and natural stresses accruing from climate change in the region. The forecasts of the six models provide a range of possible impacts of the various stresses on the system. This research finds that groundwater resources in the terrain are vulnerable to the impacts of climate change and enhanced abstractions to meet growing domestic water resources requirements. The business-as-usual scenario whereby groundwater abstraction rates continue at the current rate of population growth, with the same levels of groundwater recharge is not sustainable. This is likely to be worsened by reduced groundwater recharge resulting from enhanced anthropogenic activities and climate change. The six versions of the numerical model over the domain, although provide different results, all agree on the impacts of prevailing and future stresses on the system.