Technical Report No. 72
Edmond D.H. Cheng, L. Stephen Lau
Monthly rainfall data of several stations in Kalihi Basin, Manoa Basin, and Kaneohe Area, all on Oahu, and the central sloping area of Molokai were correlated to watershed parameters of the areas. Distance measured from the station to a common station located seaward from all stations has proven to be the most important of the three parameters studied, the other two being the exposure and the elevation of the area. Both linear and nonlinear regression functions were developed.
The central tendency of the monthly rainfall for the high rainfall part of the southeastern part of the Island of Oahu was found to require approximately forty years of record to stabilize. The analysis also shows that mean converges. to a specified level generally faster than median.
The intensity-duration relation of intense rain for specified recurrence interval for the high rainfall part of the Manoa Basin portrays accurately an inverse straight-line relationship on a plot of log-log coordinates, suggesting extension of effort to other climatically widely different regions in Hawaii. The developed relation agrees well with the reported finding of a prior Weather Bureau study employing a different approach.