Groundwater Modeling of a Deep Coastal Aquifer System in Tanzania Guided by Hydrocarbon Exploration Data
The conceptual model was used as the basis for numerical model development. A three-dimensional groundwater model of the aquifer system was built, calibrated and applied to examine sustainability of aquifer development alternatives (including risk of seawater intrusion) and potential environmental impacts (stream reductions, wetland depletion). The regional-scale model, which covers 4,400 mi2 (73% of which are off-shore) simulates the hydraulic interaction between fresh and saline groundwater (with the deep aquifer interface estimated to be over 10 miles offshore) as well as discharges to surface water onshore.
Based on the modeling, the estimated quantities of groundwater that can be developed in the long-term from the KAS can be as high as 70 MGD, depending on how wellfield development proceeds. Different wellfield configurations were tested with the model, which indicated that sustainable yield is more likely to be constrained by available drawdowns in production wells and other operational constraints than by seawater intrusion. For the wellfield configurations selected for further development, the groundwater model was used to examine potential protection zones, potential environmental impacts, times of travel, and groundwater age.