Numerical modelling of vertically extensive groundwater bodies in Maui, Hawaii: An alternative to perched aquifers

Groundwater in East Maui, Hawaii is traditionally described as a series of discrete aquifers perched on low-permeability units underlain by a basal lens with heads of about 2-3 m. An alternative concept, a fully saturated aquifer to as much as 1400 m elevation, was investigated using a numerical model with various horizontal hydraulic conductivity values and anisotropy ratios. Results indicate that horizontal hydraulic conductivity values between about 0.08 and 1.0 m per day and anisotropy ratios between 1:1 and 100:1 will produce simulated water tables that match observed water tables at 400-1400 m elevation. These values of hydraulic conductivity are consistent with available field data for hydraulic conductivity.Groundwater in East Maui, Hawaii is traditionally described as a series of discrete aquifers perched on low-permeability units underlain by a basal lens with heads of about 2-3 m. An alternative concept, a fully saturated aquifer to as much as 1400 m elevation, was investigated using a numerical model with various horizontal hydraulic conductivity values and anisotropy ratios. Results indicate that horizontal hydraulic conductivity values between about 0.08 and 1.0 m per day and anisotropy ratios between 1:1 and 100:1 will produce simulated water tables that match observed water tables at 400-1400 m elevation. These values of hydraulic conductivity are consistent with available field data for hydraulic conductivity.