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<br />In.urance Act of 1968, end further with the p....go. Qf the rlood Oi...ter <br />PrQtection Act of 1973. Th. 1968 Act prQvlded for the Availability Qt flood <br />in.urAnce within commun1ties that were willing to adopt flood plain ..n4ge..nt <br />pr09ra.. to .itigat. future flood 10..... The Agt al..o requir.d tha flOOd <br />plain ..tudie. within the United State.. and th.. ...tablis~nt ot flood-ri..k <br />zonea within tho.e Ar.... <br /> <br />are... .re <br />inoluded. <br /> <br />not oon.1d.red, 1... flood routln9 proo,,' 1a not <br />Th. wat.r .~rf.oe profile i.. .tationAry in ti... <br /> <br />3. <br /> <br />flow is one-4taen..ion.l, the only velocity component i. in the <br />direotion of flow and the water .urtace i. horizont.l over the <br />.ntir. cro... ..ction, <br /> <br />FLOOD INSURANCE STUDY GUIDELINES AND SPECIFICATIONS <br />The c~rrent FLood In8urance Study Guidalin.s and ~.cificatione are <br />provided for work involving .tandArd prote..ional practice tor flood hazard <br />evaluation, whereA8 8pecific instructions ar. al.o provided tor work unique to <br />flood insuranc. studi.... The studi.. ..hould prov1~ co.-unit i.. with <br />eufficient technical information to enable th.. to adopt the tloodplain <br />management measures and to establish actuarial flood 1n.urance prem1~. <br />A flood in~urance study generally involve. appra1..ing a community'. tlood <br />problems, estimating floodflow frequency of flooding .ouree. (hydrolo9Y), <br />e8tablishing flood elevation prot!le. (hydraulic.), plotting fl004 boundaries <br />(floodplAin mapping), computing flood hazard factor. (insurance rate..), and <br />delineating floodway.. The hydra~lio analyeia in the flQOd inaurano. study <br />determine. the flood elevationa along the atrea. ohannel uainq a hydraulic <br />~deling technique. Currently FEMA .~oify the U.8. Aray Corps ot Engin.era <br />Hydrologic Engineering Center's go8nera1i*ed ~ut'r pr09ra. nsc-2 1e <br />recomaended. The use of alternate com~uter progr... ~.t be approvad by the <br />project officer of rEKA. <br /> <br />s. <br /> <br />flow i. gradually varied, i~lying a hydroatatic presaure <br />dhtribut.1onl <br />the ......11. elope (cod I 1) La a..wned, .0 that the vuticlll dill <br />of water 1. repre.entative of the pre..ure head, and <br />6. Th. Menning equation for uniform flow applies to gradually vadE <br />flow. <br /> <br />4. <br /> <br />Accord.1ng to the cOlMlent. ot nMA '. 'tudiaa from public . <br />local 0!f1cial. 1n ~gion VlII, the major deficienclee of the current wat. <br />..urtace elavation determination ~dal ara the fixed-bed, at.ady atate and <br />dimenalonal a.sumptions. <br /> <br />EXPERIENCED MAJOR HYDRAULIC PROBLEMS IN REGIONS VIII. IX .nd X, FEMA <br />The ...jor hydrauU.c proble.. of flood in.urance atudie. in FEMA" w.. <br />reg10n. are .WlUIIArie4 .. follows I <br /> <br />_ .tre.. channel bottom aegradation or .ggregation <br /> <br />_ .tre.. ohannel bank ero.lon and undartll.ln!ng <br /> <br />. .tre.. Qhannel la~eral ai9ratlon or braiding <br /> <br />LIMITATIONS Of HEC-2 HYDRAULIC MODEL <br />The HEC-2 was developed to determine water .urf.ce elevation. by .tan4ard <br />Btep method for given diacharges in river chann,le of any oros. .ection for <br />The effect. of natural <br /> <br />_ .eriou. ero.lon probl... at hydraullQ structur.. <br />_ larg_ &mOunt of ..~i..nt. tran.port.~ in the Itream <br /> <br />_ debris and .ediment blockage at ro.oway cro.sings <br /> <br />_ ..di~ent problema in tbe alluyial fan area. <br /> <br />aubcritical or supereritical ateady-'tabl. flow. <br />obatructions <br /> <br />to flow, floodplain encroachment, and hydraulio ,truceur.. may be <br />the progrAm. The assumption.. or li=1tation. are the following I <br /> <br />_ landtl1d. in upper b.ein. with mu~now in channels and on alluvial f. <br /> <br />1. <br /> <br />a rigid or fixed boundary, i... no aedimene .cour or deposltion 1n <br />the channel, <br /> <br />_ sedi~.ntation problema in urban areas <br />_ channel end overbank storag' effects on flood stage predication <br /> <br />simulated by <br /> <br />,. <br /> <br />flow is steady, ~.e. the paSSAge of a flood wave cannot be <br />accurately analyzed. the flood ..tor&ge ln the channel and overbank <br /> <br />As indicated above, all hydraulic proble~ of FIS in FEMAI. western <br />re9ioo, ar. ...ociate4 with erodible channel. an4 sedimentation. Therefo <br />it i. important to clarity the applioability of current 8imple fbed-bed <br /> <br />3.J{) <br /> <br />3.31 <br /> <br />< <br />