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<br />Term <br />North American <br />Vertical Datum 1988 <br />(NA VD 1988) <br /> <br />National American <br />Datum 1983 (NAD <br />1983) <br /> <br />National Geodetic <br />Vertical Datum 1929 <br />(NGVD 1929) <br /> <br />North American <br />Datum 1927 (NAD <br />1927) <br /> <br />100-year flood <br /> <br />100-year Floodplain <br /> <br />Post Wildfire <br />Hydrology <br /> <br />Raster Images <br /> <br />Regulatory <br />Floodplain <br /> <br />Stream Alteration <br />Activity <br /> <br />Definition <br />The vertical adjustrnent system using the new sea level datum from the <br />1980's. It redefines the heights of several hundred thousand benchmarks <br />across North America. <br /> <br />Refers to North American Datum of 1983. <br /> <br />Based on the sea level vertical datum of 1929. <br /> <br />Refers to the North American Datum of 1927. <br /> <br />A flood having a recurrence interval that has a one-percent chance of <br />being equaled or exceeded during any year (I % chance exceedance <br />probability). The terms "one-hundred-year flood" and "one percent chance <br />flood" are synonymous with the term "IOO-year flood". The term does not <br />imply that the flood will necessarily happen once every one hundred years; <br />however a flood of this magnitude is expected to be equaled or exceeded, <br />based on long-term averages, once during any given one hundred year <br />period. <br /> <br />The area of land susceptible to being inundated as a result of the <br />occurrence of a one-hundred-year flood. This term is synonymous with the <br />term "state regulatory floodplain." <br /> <br />Methodologies and calculations developed to account for the increased <br />water runoff after forest fires. Post-wildfire hydrology shall be evaluated <br />every 3 to 5 years to assess the need for further revision based on <br />watershed recovery, forest regrowth, and other factors. <br /> <br />A raster image is a collection of dots called pixels. Each pixel is a tiny <br />colored square. When an image is scanned, the image is converted to a <br />collection of pixels called a raster image. Scanned graphics and web <br />graphics (JPEG and GIF files) are the most comrnon forms of raster <br />Images. <br /> <br />The Regulatory Floodplain IS synonymous with the 100-year, or 1% <br />chance, floodplain. <br /> <br />Any manmade activity within a stream or floodplain that alters the natural <br />channel, geometry, or flow characteristics ofthe stream. <br /> <br />9 <br />