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<br /> <br /> <br /> <br />40,000 <br /> <br />> ,'~':), <br /> <br /> <br />ij <br />% <br />~ <br />I <br />~ <br /> <br />35,000 <br /> <br />Q <br />2 <br />Q <br />~ 30,000 Five-year <br />(;) moving average <br />'" <br />w <br />"- <br />Iii 15,000 <br />~ <br />u <br />a; <br />a 20,000 <br />;!; <br />;;:' <br />'" <br />~tLi 15,000 <br /> <br /> <br />11@i10'000 <br />,2 <br />,'~ <br />t 5,000 <br /> <br /> <br /> <br /> <br />i"'~':' ..""" "':f' "," -" ."~" ,.,,- "" <br /> <br /> <br />erhaps now superimposed on indication that a lonirm trend in <br />ng~rm human;l!1puced trends) annuai peak flowsw;t~~sro exists <br />atiaffect hydrolqgic conditions'~ (flg. 11). Llkewlse/ali!(lnston, 5 of <br />N~~i~al Rege~J,~f:l:councillJ,. the 11tflood peaks'i.1~terthan <br />,909mv.Consegu\,ntiy, the I~nger 20,000 ft3/s occum~~lltiring the <br />"e.~~&sof recof,<.!:!)'1f!Y incll\ei' 10-year period 19~~7 (fig. 12). <br />eflQds during,whlch4lood risk is On the other haIjlt'a longer <br />~~'nt frorrt.!ScO'irent p,i~d or period of record r;~es the vari- <br />eruture desigl1period.forexam- ance in the estimat~d recurrence <br />Ur of th'~t)ye largest fltlods intervals. The 90'p~itent confr- <br />the last] 02 years at;Tarboro dence band forthe't1 DO-year flood <br />I:g:;giiJfed~uring the peri "'1919- flow. estimated for~e Tar River at <br />40;(fig. 11). However, t no Tarboro is fairly narrow (table 4). <br />m <br /> <br />@ <br /> <br />% <br /> <br /> <br /> <br />hils Dam <br />closed <br /> <br />I@ <br /> <br />ffi <br /> <br />However, the 90-percent confi- <br />dence band for the 1 DO-year flood <br />estimate for the Neuse River at I@ <br />Kinston, where 19 years of record, <br />were use~}n the analysis, is qULW <br />large and represents a range in ~ <br />stage of more than 5 feet. In tht)",' <br />relatively flat topography of the <br />Coastal Plain, this uncertainty in <br />the 1 DO-year flood elevation can <br />translate to a large uncertainty in <br />the delineation of the regulatory <br />1 DO-year floodplain. <br /> <br />~ <br />@ <br /> <br />m <br />Table 4. "Effect of period of record 0 <br /> <br />and Neuse River at Kinston, N.C. , <br /> <br />[frlis, cubic feet per second; -, not com~uted. <br /> <br />... ...... ---- <br /> <br />100'~ar flood magnitude, Tar River at Tarboro <br /> <br />I <br /> <br />~ <br /> <br />Period of record <br />Comput_ed I DO-year flood flow, in ft is <br />90-percent confidence band. in ft is <br /> <br />18.9.7#.1999 <br />!14?,5oo <br />39;10Q.l53,5oo <br />@ <br /> <br />Neusc Rivf"r lilt Kin~ton <br /> <br />1981-1996 <br />28.200 <br />~ % <br /> <br />1981-1999 <br />40.500 <br />29,300-68.700 <br /> <br />Two Months of Flooding in Eastern ~orth Carolina, September-October 1999 <br /> <br />-- <br /> <br />!II W <br /> <br /> <br />1@ <br />w <br />mfl!! <br />I: <br /> <br />m <br />WI> <br />I@ <br /> <br />'" <br /> <br />~; <br />.i;, <br /> <br />