Rainfall and Runoff in the Leeward Koolau Mountains, Oahu, Hawaii

Abstract

During the course of the investigation of the ground-water resources of southern Oahu, made by the U. S. Geological Survey in cooperation with the State of Hawaii, a water-budget study was used to estimate the quantity of ground water available for development. The effective use of this approach required a detailed knowledge of rainfall and runoff in the area being studied, especially in that part of it lying in the wet Koolau mountains, where most of the ground water is recharged. Past estimates for the rainfall-runoff relationship in this environment were rather speculative, and were based either on extrapolations from areas of lower rainfall or on experience obtained elsewhere. In the present study it became obvious that this relationship would have to be refined.