WRRCTR No. 17 Estimation of ground water configuration near Pahala, Hawaii using electrical resistivity techniques.

Abstract

In 1965 the Water Resources Research Center of the University of Hawaii began development of the necessary equipment to explore the feasibility of an extensive resistivity exploration program. Subsequent funding permitted the organization of this project with the dual purpose of developing reliable and convenient instrumentation for resistivity surveying in the Hawaiian islands and to apply the technique toward the solution of a ground water problem in Pahala, on the island of Hawaii. A series of 14 electrical soundings was completed at Pahala in September 1966 in an attempt to determine the extent and causes of an anomalous high water table. Four of the soundings indicated the limits of this underground reservoir to be at least 3500 feet east and 2500 feet south of a Maui-type well shaft in Pahala. The southern extent of the high head ground water suggests the northeast-southwest trending of the eruptive fissure vent about 4000 feet southeast of the well as a likely hydrologic barrier. Other soundings, indicating intermediate level water tables along the direction of the strike of the vent toward Punaluu, suggest a series of similarly trending dikes forming steps of water entrapment dropping toward the ocean. To the north of the hypothetical sequence, a set of somewhat confused soundings indicate what may be ancient buried soil or ash surfaces serving as impermeable boundaries presenting direct normal ground-water flow from Pahala southwest above the dikes to the ocean south of Punaluu.