Floods happen...anywhere, anytime
Floods can and do happen in Hawai‘i County - anywhere and at any time. Flooding can be caused by heavy rains, ponding, surface runoff, high seas, hurricane and tropical storm surge, and tsunami inundation.
No district on the island is immune from flooding hazards. While some parts of the island receive more annual rainfall than others, all districts can be susceptible to heavy rains that create runoff—flooding roads, property, homes and businesses.
The Big Island, being geologically very young, has not developed defined waterways in many areas. Poorly defined waterways often overflow during rainstorms, especially in the South Kohala, North Kona, South Kona, Ka‘u, Puna, North Hilo and South Hilo districts. Even very small streams, gulches, culverts, low-lying ground or dry streambeds that appear harmless in dry weather can flood. And coastal areas of the island are susceptible to high seas and tsunami inundation.
For general geographical descriptions, present flooding and drainage issues, and courses of action for the reduction of the flood and drainage problems in the nine County districts, see "Flooding and Natural Disasters" section 5 of County of Hawai‘i General Plan.