Geophysical surveys for characterizing the hydro-geologic regime in the vicinity of Kealakehe, Hawaii

Abstract

"The primary objective of the geophysical survey was to determine the elevation and thickness of the lens of fresh water floating on salt water. Fresh water in these settings is found in two environments: 1. Dike-confined waters -- Typically, above the rift zone, intrusive dikes originating from a magma source below can form ground water dams, and behind these natural dams significant quantities of ground water can be stored. 2. Basal fresh water -- The high permeability of the volcanic rocks allows sea water to enter freely under the island, and a delicate balance is reached where a lens of fresh water floats on sea water."