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<br />Fig.i. <br /> <br />BASIC <br />RELATIONSHIPS <br /> <br />DERIVED <br />RELATIONSHIPS <br /> <br />Basic and Derived Evaluation Relationships <br /> <br />S_-DamaQO <br /> <br />Slogo- Flow _ <br /> <br />Flow-Frequency <br /> <br /> <br /> <br />., <br />I <br />. <br />. <br />iL <br /> <br /> <br />.. <br />, <br />---------------z, - <br />l! <br />.. <br /> <br />F,.quency- f <br /> <br />, <br />, <br />, <br />..- <br />,/ <br /> <br />Flow-Q <br /> <br />, <br />" <br />" <br /> <br />'....O'am~. - $ <br />, <br />I <br />, <br />I -- --- <br />\ --- <br />\ Flow - OamaC)e / -- <br />\ / <br />\ ..-/ <br />\ ..- <br />\ ' <br />\ I <br /> <br />, <br />, <br />I <br />, I <br />.....--......~StClQe-Frequen<::)' / <br /> <br /> <br />:/ <br /> <br /> <br />/,..- <br /> <br />FreqlHln~- f <br /> <br />Oom...- $ -- __ <br /> <br />OoIllOQl-F_cy <br /> <br />-- <br /> <br />--- <br /> <br />--- <br />,- <br /> <br /><I> <br />, <br />. <br />ll' <br />. <br />8 <br /> <br />-- <br />, <br />.... <br /> <br />, <br />/ <br />I <br />~ <br /> <br />1.0 <br /> <br />o. <br /> <br />FrlqlHllRCy- , <br /> <br />The basie functional evaluation relationships and the derived relationships <br />are shown above and now they are constructed 15 described herein. <br /> <br />StaQe-Flow Relationship: This is a basic hydraulic function that exoresses. <br />for a specfffc location, the relationship between flow rate and staqe and is <br />frequ~tly referred to as . 'ratfnq curve.' It is usually derived from water <br />surface profile computatfo~s. <br /> <br />StaQP.-na~oe Relationship: This is the economic countemart to the sta~e- <br />flow funct10n and reDrespnts. at a soeci~ic location. the da~~es which <br />will occur in a river reac,", at various river stanes. usually the dal'tane <br />renresents an anflreQate of rlaMal.'te which occur SOI'le distance IJJlStreatn and <br />downstream from the spec1f1ed location. It is usuallY r1eyelnnetl -FrQfll fielrl <br />daNge surveys. <br /> <br />Flow~FreQuency Relattonshi~ This defines the relationship between exceedance <br />frequency and of annual Del flow at a location. It is the bastc function <br />describing the probability nature of stream flow and is commonly determined <br />from either statistical analysts of gaged flow data or throuqh watershed model <br />calculations. <br /> <br />Damale.FreQuency Relationship: This relationship is derived by cOMbfning the <br />prey ouslY discussed bastc relationShips usinq the common oaramete~ stafle and <br />flow. For example. the daNge for a snec:ific exceedance frequency is deter- . <br />mined by ascertaining the correspondfng flow rate from the flow-frequency <br />function. the corresponding stage from the staae-flow function and finally <br />the corresponding damage froM the stage.damage relatfonshiD. Any changes which <br />occur fn the stage.damaoe. stage.flow or flow.frequency function because of <br />watershed. development or flood plain wmnagement measure implementation will <br />be reflected in the da~qe-freQuency function and therefore the magnitude of the <br />exPected annual damage c~uted as the 1Ategral (area underneath) the function. <br /> <br />Other Functional RelatfonSh1ps: The flOw.dana~e relat1onshi~ is develnr~ <br />by comb1n1nq the stage-~a~ge with the staoe.11ow relatfons~in USfA" sta~e <br />as the common oarameter. The staQe-frequency relationship is develoned bv <br />combining the stage-flow with the flow-frequency relationshfo usinn floW <br />as the cOfllfllOn narameter. The da~ge.freouency relatfonshin could then be <br />developed as a further combination of these derived relationships. <br /> <br />EXHIBIT 1 <br />2 OF 12 <br />