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<br />Federal Emergency Management Agency <br /> <br />design of flood control structures or <br />flood plain land use regulation. <br />(ii) It must be well-documented In- <br />cluding source codes and user's manu~ <br />also <br />(!ii) It, must be avallable to FEMA <br />and all present and future parties im- <br />pacted by flood insurance mapping de- <br />veloped or amended through the use <br />of the program. For programs not gen~ <br />erally available from a Federal agency. <br />the source code and user's manuals <br />must be sent to FEMA free of charge. <br />with fully-documented permission <br />from the owner that FEMA may reo <br />lease the code and user's manuals to <br />such impacted parties~ <br />(7) A revised hydrologic analysis for <br />flooding sources with established base <br />flood elevations must include evalua- <br />tion of the same recurrence interval(s) <br />studied in the effective FIS. such as <br />the 10-. 50-. 100-. and 500-year flood <br />discharges. <br />(8) A revised hydraulic analysis for a <br />flooding source with established base <br />flood elevations must include evalua- <br />tion of the same recurrence interval<s) <br />studied in the effective FIS. such as <br />the 10-. 50-. 100-. and 500-year flood <br />elevations, and of the floodway. Unless <br />the basis of the request Is the use of <br />an alternative hydraulic methodology <br />or the requestor can demonstrate that <br />the data of the original hydraulic com- <br />puter model is unavailable or its use is <br />inappropriate. the analysis shall be <br />made using the same hydraulic com- <br />.puter model used to develop the base <br />flood elevations shown on the effec- <br />tive Flood Insurance Rate Map and <br />updated to show present conditions in <br />the flood plain. Copies of the input <br />and output data from the original and <br />revised hydraulic analyses shall be <br />submitted. <br />(9) A hydrologic or hydraulic analy- <br />sis for a flooding source without estab- <br />lished base flood elevations may be <br />per10rmed for only the 100-year flood. <br />(10) A revision of flood plain delinea- <br />tions based on topographic changes <br />must demonstrate that any topograph- <br />ic Changes have not resulted in a <br />floodway encroachment. <br />(11) Delineations of flood plain <br />boundaries for a flooding source with <br />established base flood elevations must <br />provide both the 100- and 500-year <br /> <br />~ 65.6 <br /> <br />flood plain boundaries. For flooding <br />sources without established base flood <br />elevations, only 100-year flood plain <br />boundaries need be submitted. These <br />bOWldaries should be shown on a topo- <br />graphic map of suitable scale and con- <br />tour interval. <br />(12) If a community or other party <br />seeks recognition from FEMA. on its <br />FHBM or FIRM. that an altered or re- <br />located portion of a watercourse pro- <br />vides protection from. or mitigates po- <br />tential hazards 01. the base flood. the <br />Administrator may request specific <br />documentation from the community <br />certifying that. and describing how. <br />the provisions of i 60.3(b)(7) 01 this <br />,subchapter wlll be met for the particu- <br />lar watercourse involved. This docu- <br />mentation, which may be in the form <br />of a written statement from the Com- <br />munity Chief Executive Officer. an or- <br />dinance, or other legislative action, <br />shall describe the nature of the main- <br />tenance activities to be performed, the <br />frequency with which they wlll be per- <br />formed. and the title of the local com- <br />munity official who will be responsible <br />for assuring that the maintenance ac- <br />tivities are accomplished. <br />(3) Notwithstanding any other pro- <br />visions of i 65.6. a community may <br />submit. in lieu of the ,documentation <br />specified in i 65.6(a)(12). certification <br />by a registered professional engineer <br />that the project has been designed to <br />retain its flood carrying capacity with. <br />out periodic.maintenance. <br />(b) Data requirements for correctin~ <br />map errors. To correct errors in thE <br />original flood analysis, technical daUl <br />submissions shall include the follow, <br />ing: <br />0) Data identifying mathematics.: <br />errors. <br />(2) Data identifying measuremenl <br />errors and providing correct measure <br />ments. <br />(c) Data requirements for change! <br />physical conditions. Revisions basec <br />on the effects of physical changes thai <br />have occurred in the flood plain shal <br />include: <br />(0 Changes affecting hydrologic con <br />ditions. The following data must bl <br />submitted: <br />(i) General description 01 thl <br />changes (e.g., dam, diversion channel <br />or detention basin). <br /> <br />355 <br />