USA Flood Hazard Areas

<div><font size='3'>The </font><a href='https://www.fema.gov/' target='_blank' rel='nofollow ugc noopener noreferrer'>Federal Emergency Management Agency</a><font size='3'> (FEMA) produces </font><a href='https://www.fema.gov/flood-insurance-rate-map-firm' target='_blank' rel='nofollow ugc noopener noreferrer'>Flood Insurance Rate maps</a><font size='3'> and identifies </font><a href='https://www.fema.gov/special-flood-hazard-area' target='_blank' rel='nofollow ugc noopener noreferrer'>Special Flood Hazard Areas</a><font size='3'> as part of the </font><a href='https://www.fema.gov/national-flood-insurance-program' target='_blank' rel='nofollow ugc noopener noreferrer'>National Flood Insurance Program's</a><font size='3'> floodplain management. Special Flood Hazard Areas have regulations that include the mandatory purchase of flood insurance for holders of federally regulated mortgages. In addition, in the USA, this layer can help planners and firms avoid areas of flood risk and also avoid additional cost to carry insurance for certain planned activities.<br /></font></div><div><font size='3'><br /></font></div><div style='text-align:left;'><font size='4'>Dataset Summary</font></div><div><font size='3'><b>Phenomenon Mapped:</b> Flood Hazard Areas</font></div><div><font size='3'><b>Units:</b> None</font></div><div><font size='3'><b>Cell Sizes:</b> 10 meters (default), 30 meters, and 90 meters<br /></font></div><div><font size='3'><b>Source Type:</b> Thematic</font></div><div><font size='3'><b>Pixel Type: </b>Unsigned integer</font></div><div><font size='3'><b>Data Coordinate System: </b>USA Contiguous Albers Equal Area Conic USGS version (contiguous US, Puerto Rico, US Virgin Islands), WGS 1984 Albers (Alaska), Hawaii Albers Equal Area Conic (Hawaii), Western Pacific Albers Equal Area Conic (Guam, Northern Mariana Islands, and American Samoa)</font></div><div><font size='3'><b>Mosaic Projection:</b> Web Mercator Auxiliary Sphere</font></div><div><font size='3'><b>Extents:</b> Contiguous United States, Alaska, Hawaii, Puerto Rico, Guam, US Virgin Islands, Northern Mariana Islands and American Samoa.</font></div><div><font size='3'><b>Source:</b> Federal Emergency Management Agency (FEMA)</font></div><div><font size='3'><b>Publication Date:</b> December 12, 2022<br /></font></div><div><font size='3'><b>ArcGIS Server URL:</b> https://landscape11.arcgis.com/arcgis/</font></div><div><font size='3'><br /></font></div><div><font size='3'>This layer is derived from the </font><font size='3'><font size='3'>December 12, 2022</font> version </font><a href='https://www.fema.gov/flood-insurance-rate-map-firm' target='_blank' rel='nofollow ugc noopener noreferrer'>Flood Insurance Rate Map</a><font size='3'> feature class S_FLD_HAZ_AR. The vector data were then flagged with an index of 88 classes, representing a unique combination of values displayed by three renderers. (In three resolutions the three renderers make nine processing templates.) <a href='https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/repair-geometry.htm' target='_blank' rel='nofollow ugc noopener noreferrer'>Repair Geometry</a> was run on the set of features, then the features were rasterized using the 88 class index at a resolutions of 10, 30, and 90 meters, using the </font><a href='https://desktop.arcgis.com/en/arcmap/10.3/tools/conversion-toolbox/polygon-to-raster.htm' target='_blank' rel='nofollow ugc noopener noreferrer'>Polygon to Raster</a><font size='3'> tool and the &quot;MAXIMUM_COMBINED_AREA&quot; option. <br /></font></div><br /><div><font size='3'>Not every part of the United States is covered by flood rate maps. This layer compiles all the flood insurance maps available at the time of publication. </font><br /><div><font size='3'><br /></font></div><font size='3'>To make
analysis easier, areas that were NOT mapped by FEMA for flood insurance
rates no longer are served as NODATA but are filled in with a value of
250, representing any unmapped areas which appear in the US Census'
boundary of the USA states and territories. The attribute table corresponding to value 250 will indicate that the area was not mapped.<br /></font></div><div><font size='4'><b><br /></b></font></div><div><font size='4'>What can you do with this Layer?</font><font size='3'> <br /></font></div><div><font size='3'>This layer is suitable for both visualization and analysis across the ArcGIS system. This layer can be combined with your data and other layers from the </font><a href='https://livingatlas.arcgis.com/' target='_blank' rel='nofollow ugc noopener noreferrer'>ArcGIS Living Atlas of the World</a><font size='3'> in ArcGIS Online and ArcGIS Pro to create powerful web maps that can be used alone or in a story map or other application.</font></div><div><font size='3'><br /></font></div><div><font size='3'>Because this layer is part of the </font><a href='https://livingatlas.arcgis.com/' target='_blank' rel='nofollow ugc noopener noreferrer'>ArcGIS Living Atlas of the World</a><font size='3'> it is easy to add to your map:</font></div><div><ul><li>In ArcGIS Online, you can add this layer to a map by selecting <i>Add</i> then <i>Browse Living Atlas Layers</i>. A window will open. Type &quot;flood hazard areas&quot; in the search box and browse to the layer. Select the layer then click <i>Add to Map</i>.</li><li>In ArcGIS Pro, open a map and select <i>Add Data</i> from the Map Tab. Select <i>Data</i> at the top of the drop down menu. The Add Data dialog box will open on the left side of the box, expand <i>Portal</i> if necessary, then select <i>Living Atlas</i>. Type &quot;flood hazard areas&quot; in the search box, browse to the layer then click OK.<br /></li></ul></div><div><font size='3'>In ArcGIS Pro you can use the built-in </font><a href='https://pro.arcgis.com/en/pro-app/help/data/imagery/raster-functions.htm' target='_blank' rel='nofollow ugc noopener noreferrer'>raster functions</a><font size='3'> to create custom extracts of the data. Imagery layers provide fast, powerful inputs to geoprocessing tools, models, or Python scripts in Pro.</font></div><div><font size='3'><br /></font></div><div><font size='3'>The </font><a href='https://doc.arcgis.com/en/living-atlas/#s=0&amp;n=0&amp;d=1&amp;col=&amp;fs=0&amp;fn=30&amp;npp=120&amp;subCat=0' target='_blank' rel='nofollow ugc noopener noreferrer'>ArcGIS Living Atlas of the World</a><font size='3'> provides an easy way to explore many other beautiful and authoritative maps on hundreds of topics like this one.</font></div><div><font size='3'><br /></font></div><div><font size='3'><span style='font-weight:bold;'>Processing Templates</span><br /><br /><span style='text-decoration:underline;'>Cartographic Renderer</span>
- The default. These are meaningful classes grouped by FEMA which group its own Flood Zone Type and Subtype fields. This renderer uses FEMA's own cartographic interpretations of its flood zone and zone subtype fields to help you identify and assess risk. <br /></font></div><div><br /><font size='3'><font size='3'><span style='text-decoration:underline;'>Flood Zone Type Renderer</span> - Specifically renders FEMA FLD_ZONE (flood zone) attribute, which distinguishes the original, broadest categories of flood zones. This renderer displays high level categories of flood zones, and is less nuanced than the Cartographic Renderer. For example, a fld_zone value of X can either have moderate or low risk depending on location. This renderer will simply render fld_zone X as its own color without identifying &quot;500 year&quot; flood zones within that category.<br /></font></font></div><div><br /><font size='3'><font size='3'><font size='3'><span style='text-decoration:underline;'>Flood Insurance Requirement Renderer</span> - Shows Special Flood Hazard Area (SFHA) true-false status. This may be helpful if you want to show just the places where flood insurance is required. A value of True means flood insurance is mandatory in a majority of the area covered by each 10m pixel.<br /></font></font></font></div><div><font size='3'><font size='3'><font size='3'><br /></font></font></font></div><font size='3'>Each of these three renderers have templates at three different raster resolutions depending on your analysis needs. To include the layer in web maps to serve maps and queries, the 10 meter renderers are the preferred option. These are served with overviews and render at all resolutions. However, when doing analysis of larger areas, we now offer two coarser resolutions of 30 and 90 meters in processing templates for added convenience and time savings.<br /></font>