Robert H. Dale 1978 <p>The Waialua basal-water body underlies an area of about 18 square miles on the north shore of the island of Oahu, Hawaii. The basal-water body is a body of fresh ground water that floats on saline ground water in a highly permeable and porous basaltic aquifer.</p> <br> <p>Inflow to the basal-water body is from the deep infiltration of applied irrigation water and from leakage through a low permeability ground-water dam. Outflow from the basal-water body is from basal-water pumpage and leakage through low-permeability boundaries that separate the basal-water body from the ocean.</p> <br> <p>The basal-water flux, computed as either the sum of the inflow terms or the sum of the outflow terms, is about the same value. The basal-water flux is 55 million gallons per day, (206,000 cubic meters per day), based on the sum of the outflow terms.</p> <br> <p>The effective porosity was computed at 0.09 by a time-series analysis of the covariations in deep infiltration, pumpage, and basal-water head. The volume of basal water in storage is estimated to be 1.4 x 10¹¹ gallons (5.4 x 10⁸ cubic meters).</p> <br> <p>Pumpage from the basal-water body can be increased. The most efficient development method is the skimming shaft. If shafts were used, an additional 15 million gallons per day could be pumped on a sustained basis.</p> application/pdf 10.3133/ofr7824 en U.S. Geological Survey A ground-water inventory of the Waialua basal-water body, Island of Oahu, Hawaii reports