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Chapter 12:Hazard Analysis—High Surf <br /> CHAPTER 12 - HIGH SURF <br /> 12.1 Description of Hazard <br /> High waves that inundate coastal areas are generated by strong winds or seismic events. The <br /> seismic-type wave is called a tsunami and covered in Chapter 9, on page 9-1. Damaging <br /> wind-generated waves occur from distant storms in the Northern and Southern Hemisphere, <br /> tropical storms, hurricanes, and localized Kona storms (see Figure 12-1).North-facing shores <br /> receive annual North Pacific swells in winter ranging from 10 to 20 feet. Usually damage- <br /> causing events from north swells are over 20 feet. Larger northeast trade waves are typically <br /> 2 to 4 feet; however, well-developed trade swells produce high waves of 6 to 8 feet that have <br /> caused damage. South-facing shores are exposed to Kona storms and southern swells, which <br /> have caused damage at heights of only 4 to 6 feet. Tropical storms and hurricanes affect any <br /> and all shorelines especially during summer and fall with damaging high waves of 10 to 30 <br /> feet. <br /> Hawaii b as WE!to <br /> 1651 Apr <br /> A,5.6 H <br /> a Hpn-.. aemxn <br /> Damaging high Upola <br /> Point <br /> waves* and 1 JanI,I <br /> 1990 Feb B-9 Rou <br /> Kohala 1e96 Fee s-+2x39 n <br /> high waves due ) WaiplO <br /> 993 9.91110 HFamen <br /> � 1596 Fee fbl]8-12nNNE <br /> _ s.H.owmaN,in Hm <br /> _t r +996 N.s 6 24 fi H awes,avrsaq. <br /> to hurricanes <br /> 1986 JenbJ+96-, nNCwall <br /> Kawalhae'WaTM <br /> Islantlwlde high wages _ ! <br /> oec 15- <br /> +919 29 High wvrc <br /> 1011—2129 an <br /> Hns Nov zl2t Hph— .1 <br /> 10]6 Feb 9-1""euA <br /> 1015 H.vts iihw <br /> 1918.1.111-1a'o"_ <br /> 1010 J-11-16 Hlghsess <br /> Ioee Ma.1-11 Hier— zer. Keahole _ Hilo Onekahakaha <br /> 1902 11 N hH - <br /> 993�1s1eHF.me..W WastCwst/Kona Polnf _ = Beach <br /> 1954 Nw2B 11 % <br /> 1969 Jan 23 Illpn Fe sunveta6hwAn....... <br /> 19x9 F b1s elvn sun.r:99 c.eu Kaa- <br /> 1a68 e 20 Hl or au" Konona <br /> ,969.1", Hlgncunalm.l.uear <br /> 0 20mi 1x11 Jane".h wn Magic <br /> ' 1012 0.5596-]0 Son Sands - <br /> 5919 Ja.6-11lgh wneM9[eas1 P a Ka Iln <br /> ,915­- <br /> I— ni9n sun.l Me9lc sn..aa Basco BCaCh {� <br /> 0 20km A.9H-16 Kp SYn <br /> 1996 Feb 6 Hsh Burt 11"ee.it Oplhikao <br /> 1066 Fab 22 Hqe iwt Nenr—I Beach <br /> Lakes and reservoirs 19e1 Ja.9-19 rW., Kefapana Kaimu <br /> 0-20001eet ,9925e.1+HMU.rty131.1 <br /> Jun zs-�" 25s r(t! South Puna Coast <br /> 2000-4000 feet rtam.n9m.nauer <br /> Sx+Bll',10-120 - 1912 1.16 Hlgn.udul <br /> 40006000 feel ,\:. 1962 au9 Is H"waves ec.ml <br /> 6000-8000 feel `~,� Kau :M N«e,110"-01 'Il—u.ream <br /> 8000-10.000 feel _ 1� 1919 Aug 11-M Su1251, Isar Jd 25 I" ane Kapet <br /> 10.000-12,0001ae1 1620 Ju11929nwH 1666 Jul ZZ-b 10.19n <br /> ISO 1 Coast � � liar,Jul l Il 6 wd low A°a'+-6 <br /> over 12,000 feel lees Hlen sun I9a5 Ju12510-1 sn sun +gas o6c�a1 <br /> 1965 Jul d 1065 S..S0.Hqn cu0 H82 Sop Is H <br /> Q Urban areas 19re M., n,,,nyn 3ml 196e Ju 22-z3 eqn wd /,�, <br /> 1966 Aup 46; r <br /> —Hlghwaya 1969 Jrn e-11 n M.dazlertr:...e <br /> Streams 1M JW 10-20 Hph wri <br /> 1992 S.F 1 LIW <br /> —Canals ' S Int +9w] .9n.12-1sn <br /> H Hurricane <br /> TS Tropical storm <br /> 10 K Height 01 wri(teal) <br /> z-1s n <br /> 'Does not include high waves due 19 tsunamis c' <br /> Figure 12-1. Storm Wave Directions and Events for Hawaii Island <br /> Large wind-generated waves can also cause storm surges (or overwash). A storm surge is a <br /> rise in the water level caused by wind forces driving water against the coast (wind set-up) or <br /> 12-1 Hawaii County Multi-Hazard Mitigation Plan <br />