Aloha sunwaiter,
The problem with the extremely heavy rainfall we can get in Hawaii is that it creates catastrophic flashfloods and with the high mountains the water picks up tremendous amounts of rocks, soil, logs and what not else and hurls them along at terrifying speeds towards developed areas.
A couple of years ago a flashflood inundated the basement of the research library of the University of Hawai'i at Manoa and destroyed much historic research, maps, microfiches, microrolls, historic books and so on.
No one had predicted that the little Manoa brook would swell over its banks to the extent that it did.
Cheerio,
CD