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<br />Tabl.l
<br />
<br />4
<br />
<br />Pd.d,.. "'.,.... ...i.. of die CQftUnrl,ll_ hiud 'Ut...
<br />
<br />It..i,,n
<br />
<br />Atu
<br />(tho~d'ol'
<br />.qu.rt.ilt.,\
<br />
<br />l+fl.v lall.nd
<br />2-DeI....u-fkld.0l'l
<br />J..chU.poe.k.
<br />4-S(lutllAthntic
<br />S-Eut.f1I Culf
<br />6-TI!nn.....-c\llllberl.nd
<br />7-ohi.o
<br />'-E..un Cnu L.II..-St. 1AoIunu
<br />9-lIe.t.r"Cr.at t.lI..
<br />IO-H"d.on lay
<br />ll-Upper l'hui..ippi
<br />12-Upper !hnouri
<br />I)-Lov.r "iuouri
<br />14-tl7V.r"'iui..ippi
<br />IS-UpptrArk.n.u-lt.d
<br />16-tcrv.r Ark.n"'-Iled-vhit.
<br />17-lit.tIH" Gulf
<br />18.-colorado
<br />19..oCrut ...ia
<br />20-SoutbPecific
<br />21~P.df,c Jlorth_.t
<br />
<br />"
<br />1I
<br />"
<br />110
<br />109
<br />"
<br />'"
<br />"
<br />"
<br />60
<br />182
<br />".
<br />"
<br />"
<br />15'
<br />III
<br />Y.I
<br />'"
<br />'00
<br />112
<br />m
<br />T,m"
<br />
<br />toul:
<br />
<br />Av.r'l.run,)f,
<br />Inch.. 111,[1"00
<br />pn ,.1:Ion.
<br />y..r d,it,
<br />
<br />24 6;'
<br />21 30'
<br />19 ~t
<br />14 lit'
<br />" ..
<br />21 59
<br />16 110
<br />18 40
<br />11 42
<br />1.6 4.6
<br />1.2 62
<br />1.0 24
<br />1.8 23
<br />16 49
<br />1.6 11
<br />14 7'
<br />).2 52
<br />1.1 I)
<br />1.1 10
<br />12 64
<br />13 IS'
<br />~
<br />
<br />Sourc.: D.Ii. "'111.r, J. J. GtUlhty, .nd I. S. Coll:I.... l'l6J. W.ur Atl..
<br />ul t.... Vatu'elI SUt.., a"le '.et, AbOut the H.tton'o Wllt.r .'.ouren. ll't.r
<br />Inforutl" C.llt'r, IIIoC. 'ort V,.htnltoo., -1..1., M.V.
<br />
<br />characteristics including the stream channel, riparian ~tnd wetland
<br />vegetation, oxbows or oxbow lakes, wetlands, Ilatural levees, and ral.sed
<br />berms or crests above the flood plain surface (adjacent to the channel)
<br />which usually contain coarser materials deposited by flood flows, etc.
<br />
<br />Maddock (1976) provided three deflnitionE' of flood plain ranging from
<br />geological, hydrological, to general. Geologically, a 1lood plain Is that
<br />area of a river valley covered with material deposited l~ flood. '
<br />Hydrologically, a flood plain is that area of a river vdley which :ls
<br />periodically overflowed by water in excess of the streall channel callacity.:
<br />A less precise definition used by some federal agencies considers a flood
<br />plain as being that area covered by a flood w'ith an average frequenc:y of
<br />recurrence of 100 years (or a 1 percent ChanCE! of occun,ing in 100 ),ears).
<br />
<br />Flood plains have traditionally been the first tOpcl,graphic areu
<br />settled for a variety of reasons. The rich alluvial latnd has an abundant
<br />water supply, high fertility, and a level contour for e8.se of develclpment.
<br />Approximately 7 percent of the total land area of the conterminous United
<br />States, with an estimated 22,000 communi tiel of 6.4 IIlillion single falllily
<br />dwellings (0.5% of the population), is on flood prone land (Costa 1978). '
<br />Using any of the three definitions, all estimat,ed one acre in 10 or 12 of
<br />all potentially cultivatable land and an aver.a,ge of one acre in 6 of all
<br />urban land may be considered flood pla.in (Stern and Stern 1980). Herein
<br />lies one of the most significant threats to the long-term survival of the
<br />ns:ion's streems. That is, flood plains periodically flood and the degree
<br />and timing of flood events are highly predictable. The net effect is that
<br />de,~lop~ent and flooding are highly illcompatible because development must
<br />,
<br />be p~olected. M- a, aeneral rula,,,floodina call only lie pl'8vented by 10"'&
<br />type "f .ever. :Channe1l1Od1ficaUon such .. cbannel1uti,on, reservoir i
<br />construction, or other type of habitat degradation. l
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