<br />FLOOD, lOO-YEAR
<br />
<br />land is temporary. (2) The land is adjacent to and
<br />inundated by overflow from a river or stream or an
<br />ocean, lake or other body of standing water.
<br />~ormally, a flood is considered as any te~porary rise
<br />in streamflow or stage, but not the ponding of surface
<br />~ater which results in significant adverse effects
<br />in the ~icinity. Adverse effects may include damages
<br />from overflow of land areas, temporary backwater
<br />effects in sewers and local drainage channels, creation
<br />of unsanitary conditions or other unfavorable situations
<br />by deposition of ~aterials in stream channels during
<br />flood recessions, use of groundwater coinc1detltwith
<br />increased strea~flow and other problems.
<br />A type of flood, including the water surface elevation
<br />dlluterriturialoccupationthereof,whichcanbeex_
<br />pected to occur at any time in a given area basec
<br />upon recorded historical precipitation and other valid
<br />,"atd, uulwilh an average statistical one percent
<br />chance ot belng equalled or exc~~ded during any on~
<br />year. Th~ terrr. is used int~rchangeably with 11: ch"nc~
<br />flood or Intermediate Regional Flood.
<br />
<br />flOOD STAGE
<br />
<br />LEFTS,,:IK
<br />
<br />DSSTRUCT10N
<br />
<br />?EAK DISCHARGE
<br />
<br />PRU3AS1LITY
<br />
<br />FLOOD CREST
<br />
<br />The r:1dxbum <;~age or elevation reached b,y the water
<br />of a flood Jt J giv~n location.
<br />
<br />FLOODFREQUEr,CY
<br />
<br />{See Probab11 i ty) Tile averag~ recurr~nce inter',al of
<br />spccificdischarges ill" water stages whicncd,e flOMing,
<br />
<br />REACH
<br />
<br />FLOOu?EA\
<br />
<br />The ma~imu~ instantJneooS discharge of a flood at a
<br />gIven location. It usually occur> at or ne,)r the tim~
<br />of the flood crest.
<br />
<br />RtCllRRE~CI: lNTERVAI.
<br />
<br />FLOQUPLA1N
<br />
<br />REFERENCE POINT
<br />
<br />IIn area in and iJdjacer.t tOa stre.:mwhich is subject
<br />to flooding ", a "e;ultuf the occurrence of a 100-
<br />Year Flood. Thus it is so advers~ to past, current,
<br />or fore~eeable co~struction or land use as to constitutQ
<br />a significant haZard to publ ic health and s~fety or to
<br />property.
<br />A graph snowi~g the relationship of water surface
<br />elevation to locat iJJn, th~ latter genera 1 \y expressed
<br />as a distance above the nouth for a stredn of wdter
<br />flowing in an ope~ channel. It is generally drawn to
<br />show the surface elevation for the crest of a specific
<br />floDd, but m~y be prepJred for the CQ"dit ions "l d
<br />giventicleorsta',;e.
<br />
<br />:<IGHTS"rJK
<br />
<br />RU~j()F F
<br />
<br />Fi.uuU ~kLlf lL~
<br />
<br />STREAM
<br />
<br />'^',~TEfiSrl~~
<br />
<br />"
<br />
<br />The stage or elevJtion Jt Which ov~rf1ow Of the
<br />natur~l banks of a stream or body of water begins
<br />in the reach or Jrea in which the elev~tion is
<br />meiJsured.
<br />
<br />The ban~ on the left side of a river, stream, or
<br />water course iJS the observer looks downstream,
<br />
<br />Any natural or mdnmJde object existing in, along,
<br />across, or projecting into any cnanr.el, water course,
<br />or regulatory flOOd hJzard area which r:1ay impede, ~~.
<br />t~rd, or change the depth or the direction of flow
<br />of water either by itself or by catching or collecting
<br />debris carried by such ~ater, or tilat is placed ~here
<br />the flow of the water might c~rry the same downstream
<br />to the damdge of life or prop~rty.
<br />
<br />The 1 arg.os t val u e of s treamfl ow at t a i ned by d f1 o~)d ,
<br />usually reoorted in unib of ctJbic hl't pl'r secDn(j ,cfs).
<br />
<br />The Jnnual chance of occurre~ce of specific hydrologic
<br />events, such as rainfrlll over a specifie;i area or peok
<br />di,charge at ,) s~ecified location. It is expressed in
<br />percent, ~,g.. 51.: re~res~nting one chance in 20 of the
<br />event occurring in any yea" or an averoCle rec~rrence
<br />of once in twentyye2rs.
<br />
<br />A seg~ent of the river defi~~d b~tw~en t~o specified
<br />poir.ts.
<br />
<br />rr~ )v~rJge il1te~'!~l of t.ic:e, 1~ ,year:;, '.,'i~11~" "hich
<br />rl 9 i v e n flood ,",' ill b e f~ x c e e d e (t 0 n (. e .
<br />A numbered point identifyin~ a specific location for
<br />correlatinq the drlta shown in vanous fo,'",s U,rou~h_
<br />Out th~ re~()rt.
<br />
<br />Tlie brlnk on the ri ght ~ ide of a r1v~r, .tream, cr
<br />o'Iater course, lOr)kin~ do',mstreac,.
<br />
<br />TI>", quantity Of ~a;~fdll \<~ic~ flc:'.,'~ O'icr t;;c :;"rf~,~
<br />to enter the streJ~ as discharge volume. The dif_
<br />ference in quantity between rainfall and runoff re~-
<br />resents 10sse, to infiltration and interc.:ption.
<br />
<br />Any natural channel or depression tnrou<jh which water
<br />flaws ei tiler cont jnuo~sly, interrni ttent1y cr periodi_
<br />cally, includir:g any artif icial ~odifi cation of the
<br />natural chdlll1el crdepressiiJr..
<br />
<br />The drJinage al.ea situated abov~ J sp~cif ied ~oint on
<br />a stream including tne area drd1ned by tributory str~o"1S
<br />w~ich ent~r the mai~ streJ~ above this point.
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