KCDP Final - 2008 (As amended 2019)

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CHAPTER 2 Kealakekua Bay. KONA TODA Y ■ Preserving the diverse coastlines, protected nearshore waters, open space, and vast untouched upland landscapes. Kona includes astonishing contrasts, ranging from near -barren lava fields, to coastal coconut groves, to dense native `ohi`a forests. The sunny, leeward climate has fostered an outdoor lifestyle epitomized by well-known events held in Kona – such as the International Ironman Triathlon, Hawaiian International Billfish Tournament, and numerous canoe regattas. In order to plan for a sustainable future, the following unique characteristics of Kona's ecosystem need to be considered: ■ Rainfall pattern. The massive domes of Mauna Loa and Hualalai shelter the Kona Coast from the predominant trade winds. In the absence of trade winds, light sea -land breezes prevail—the heating of the land during the day causes light winds to blow in from the sea, and the cooling of the land at night causes light winds to flow from the land to the sea. The sea breezes converge with trade winds that have passed through the Humu'ula Saddle and around the upper slopes of Mauna Loa, producing frequent afternoon showers over the island's interior sections and mountain slopes. This afternoon rainfall contrasts with the weather of the windward side of the island where rain most often falls near midnight. The rainfall pattern in Kona is common during the summer trade wind season, making Kona unique in the State in having its highest annual rainfall during the summer. The rainfall map reflects the sea -land breeze pattern (see Figure 2-1). Rainfall increases from the shoreline going mauka, reaching a peak between about 2,000 feet and 2,500 feet in elevation, where 60 – 80 inches can fall annually in some areas. Above this band, annual rainfall progressively declines to approximately 20 inches near the summits of Hualalai and Mauna Loa. Steep topography with undefined drainageways. Erosion has only slightly altered the lava -formed landscape of Kona. There are no perennial streams. Most rainfall, except in heavy storms, percolates rapidly into porous lava. There are recognized drainageways, but they are shallow and not well defined. Consequently, heavy localized rainfall can easily exceed the capacity of the shallow drainageways resulting in flooding of adjoining areas. Moreover, even relatively slight changes in topography through grading and other land -disturbing activities can affect the capacity of drainage courses or change the direction of flows. Areas that have not previously experienced flooding could flood during even short periods of high rainfall. The predominantly steep topography of Kona causes runoff to flow quickly, resulting in short response times to potentially rapid flooding. 2-2 KONA CDP