Analytical Groundwater Modeling for Estimating Sustainable Yield of Iao Aquifer, Maui, Hawaii

Since 1980, several numerical models of groundwater flow and salinity transport have been developed for Hawaii basal aquifers. At this time, however, they are too complicated as viable management tools because adequate calibration and verification of these models require extensive field data which are not currently available. In our study, a simple robust analytical model called RAM2 was developed by taking Hawaii basal aquifers as a completely stirred tank reactor. RAM2 consists of (a) a flow submodel and (b) a salt transport submodel which simulates the evolution of the transition zone in a basal freshwater lens. The mathematical structure of RAM2 is simple, such that it can be solved analytically and can be readily calibrated using available field data. Its usefulness as a management tool was demonstrated by applying it in an evaluation of the sustainable yield of the Iao aquifer on Maui, Hawaii.