WRRCTR No.64A Preliminary Report on Flood Hydrology and Urban Water Resources: Oahu, Hawaii

Abstract

Studies conducted during Phase I of the "Flood Hydrology and Urban Water Resources of the Island of Oahu, Hawaii" project were divided into four major tasks. The first is an examination of the causes of flooding and flood damages on Oahu. This task has been completed and data obtained reveals that historical floods in Oahu happened most frequently within the city limits of Honolulu and the Waialua area. The second task was to evaluate the effect of urbanization upon flood hydrographs from selected watersheds in Oahu. The third task was to establish the rainfall-runoff data collection devices in the adjoined urban (St. Louis Heights) and natural (Waahila) watersheds. The installation and operation of two auto-recording raingages and two auto-recording water stage recorders were completed. The fourth task was to initiate the studies of watershed simulation models. Thus far, efforts have been concentrated on two watershed simulation models. One model utilizes an auto-optimal technique in determining the instantaneous unit hydrograph. The other model is a modification of the Kentucky Watershed Model to better fit Hawaiian conditions. Additional modifications are required before a good fit is achieved by both models.