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<br /> <br />more detailed mapS at scales ranging froul 1: 12,000 to 1: 1200. This <br />level of positional accuracy is consistent with the accuracy of the <br />hardcopy FIRMs. <br /> <br />! <br /> <br />Users should assess the horizontal positional accuracy of DFIRMs <br />with regard to the selected base map source and the requirements of <br />the application. <br /> <br />I' <br /> <br />wit.h. lncreaseo frequency, highiy detaiiea idl.ot: .::"...c.J..~ l..oJ..b"'~...J... <br />mapping is becoming available. DFIRMs mOlY also be used in combina- <br />tion with these data. Users should keep in mind that even though <br />the scale of the DFIRM map may be increased to overlay these data, <br />the accuracy of DFIRMs is not improved by scale enlargement. <br /> <br />,. <br />~ ! <br /> <br />. <br /> <br />Data Model Integrity: Data set is topologically structured polygon data <br />with nodes at all intersections. <br /> <br />. <br /> <br />Con. ,leteness: Flood risk data are developed for communlt:~es pa".ticiD. ting <br />in the NFIP, for use in insurance rating, and for floodplain ma, .age- <br />ment. Flood hazard areas are determined using statistical ana~ysis <br />of records of river flow, storm tides, and rainfall; information <br />obtained through consultation with the communitys: floodplain <br />topographic surveys; and hydrologic and hydraulic analysis. Both <br />detailed and approximate analyses are employed. Generally, detailed <br />analyses are used to generate flood risk data only for developed or <br />developing areas of communities. For undeveloped areas where little <br />or no development is expected to occur, FEMA uses approximate <br />analyses to generate flood risk data. Ty'pically only drainage areas <br />that are greater than 1 square mile are studied. <br /> <br />Flood Insurance Rate Maps continually undergo revisions and updates. <br />Some of these revisions are effected by letter (Letter of Map Revi.- <br />sion, Letter of Map Amendment). DLG data files may not reflect the <br />most current information. To obtain the latest information, contac.t <br />the address listed below as Metadata cor,tact. <br /> <br />. metadata Revision Date: YYYYMMDD <br /> <br />. Metadata Contact: Assistant Administrator <br />Office of Risk Assessment <br />Federal Insurance Administrc.tion <br />Federal Emergency Management: Agency <br />500 CSt., S.W. <br />Washington, D.C. 20472 <br /> <br /> <br />10/93 <br /> <br />16 <br />