Description: The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk classifications used are the 1-percent-annual-chance flood event, the 0.2-percent-annual-chance flood event, and areas of minimal flood risk. The DFIRM Database is derived from Flood Insurance Studies (FISs), previously published Flood Insurance Rate Maps (FIRMs), flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data, where available. The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). The file is georeferenced to earth's surface using the UTM projection and coordinate system. The specifications for the horizontal control of DFIRM data files are consistent with those required for mapping at a scale of 1:12000.
Description: base_LakePolygon originated from DPU's stm_LakeShape feature class. A copy of it was placed into the Basemap dataset for the purpose of supporting basic base map map service(s). The data is not dynamic, as lakes do not come-and-go. The reason for not referencing DPU's version of lakes for base map services, is because following ESRI's notion of 'Workload Separation,' it is best to direct things away from ArcGIS Server Sites/Machines that support critical applications. Base mapping sources can be more isolated and not be dependent upon or interfer with DPU stormwater activities.base_LakePolygon was also cleaned-up of extra fields established by DPU that serve no purpose for supporting base mapping: LifeCycleStatus, InstallDate, InstallContractor, ConstructionInspector, WorkOrderNumber, OracleInquiryNumber, DPUDrawingNumber, ProjectNumber, and ProjectName.
Copyright Text: Lakes were captured by Michael Baker Corp in the City's original GIS base mapping project, with further attribution applied by DPU after the information was relocated to the Stormwater dataset.
Description: The primary funder of the 2014 Virginia Wetlands Catalog (VWC), the U.S. Department of Agriculture, Natural Resources Conservation Service (NRCS), needed a tool for ranking easements for various conservation programs, including the Wetlands Reserve Program, the Farm and Ranch Lands Protection Program, and the Grassland Reserve Program. Other funders, including Virginia Department of Conservation and Recreation-Division of Natural Heritage, The Natural Conservancy, Virginia Department of Transportation, and Virginia Commonwealth University-Center for Environmental Studies, had various needs for a tool that could be used to prioritize wetland parcels for conservation or restoration purposes, that could make project design more efficient, that could be used to assess impacts of proposed projects, and that could be used to identify possible mitigation sites. The VWC was designed to satisfy these various needs. The analysis started with development of a wetlands and streams layer by massive overlays of data from the National Wetlands Inventory, the high-resolution National Hydrography Dataset, 100-year floodplains from the Digital Flood Insurance Rate Map Database, and hydric and likely hydric soils from the Soil Survey Geographic Database. Two separate prioritizations, one focused on conservation and the other on restoration, were then applied to the wetlands and streams layer, again by massive overlays. The weighted layers used for the conservation prioritization indicated plant and animal biodiversity, significant natural communities, natural lands that provide ecosystem services, natural corridors and stream buffers, proximity to conserved lands, relatively clean watersheds, and drinking water sources. Some of these weighted layers also were used for the restoration prioritization and to them were added layers that indicated degradedwatersheds and impaired waters, existing wetland mitigation banks, prior converted and farmed wetlands, and stream reaches with depressed biodiversity that potentially could be restored. Statewide parcel and subwatershed data were incorporated into the results during the massive overlays. The various ranked and summary products were produced by analysis and processing of the resulting attribute tables, including summation of fields from the weighted inputs, reclassification of values, and reduction of data to maximum values. The results include six feature classes in a file geodatabase that are split into conservation and restoration prioritizations and summaries by wetland, parcel, and subwatershed boundaries. These six feature classes include representations embedded in them that portray the vast amounts of data thirty different ways and allow enhanced exploitation of the database. All representations can be viewed easily with the accompanying ArcMap document. The two most important of these representations are Conservation Rank and Restoration Rank, which clearly indicate relative values of wetlands with ranks 1 through 5, with five being most valuable. The VWC provides spatial tools to assist federal and state agencies, and perhaps private corporations, in designing projects efficiently, with reduced impacts, and in identifying wetlands for conservation, restoration, or mitigation purposes.
Copyright Text: Weber, J. T. and J. F. Bulluck 2014. Virginia Wetlands Catalog: An Inventory of Wetlands and Potential Wetlands with Prioritization Summaries for Conservation and Restoration Purposes by Parcel, Subwatershed, and Wetland Boundaries. Natural Heritage Technical Report 14-4. Virginia Department of Conservation and Recreation, Division of Natural Heritage. Richmond, Virginia ## pp.