CP-2005-06
Simple analytical groundwater modeling for sustainable yield estimation
Clark C.K. Liu, John F. Mink, and John Dai
Over the last twenty years, numerous modeling efforts were made to simulate the flow and salt transport processes of the Pearl Harbor aquifer, a basal freshwater lens. These modeling exercises enhanced our understanding of the aquifer. However, most of these models are too complicated, such that adequate calibration and verification require extensive field data which are not currently available. A simple robust analytical model (RAM) developed by John Mink in 1980 has been used to estimate the sustainable yield of Pearl Harbor aquifer and many other basal aquifers in the state of Hawaii. Modification of RAM is made in this study by including salt advection-dispersion processes. The modified model consists of two sub-models: (a) a flow sub-model, in the form of the original RAM, and (b) a salt transport sub-model, which simulates the evolution of the transition zone in a basal freshwater lens. The mathematical structure of the modified model remains simple such that it can be solved analytically and can be readily calibrated based on available field data of hydraulic head variations and salinity profiles. Its usefulness as a viable management tool was demonstrated by applying it hi an evaluation of the sustainable yield of the Pearl Harbor aquifer. KEY TERMS: groundwater; basal aquifer; sustainable yield.