Geophysical surveys for characterizing the hydro-geologic regime of the Puu Anahulu area of North Kona, Island of Hawaii

Abstract

"The main objective of the geophysical survey was to characterize the hydrologic regime near Puu Anahulu. In the Hawaiian islands, the volcanic rocks are generally highly permeable and rain water rapidly percolates into the ground and migrates downward to the water table. 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."