City of Seattle 2 ft contours derived from Lidar captured in 2021. Contour lines display at 2ft, 10ft and 50ft intervals dependent on scale. Lines have been smoothed and generalized for display and performance.

Development Detail:

This vector tile service includes topographic contour lines representing elevation at 2-foot intervals within the city of Seattle.

The contours were derived from a bare earth - digital elevation model (DEM) with a pixel resolution of 1.5 feet. The lidar data that created the DEM were collected by NV5 Geospatial over the spring and summer months of 2021 and provided to the city by King County in 2022.

The DEM used to generate the contours was filtered using the Focal Statistics tool in ArcGIS, which served to limit some abrupt changes in cell values. A 3x3 rectangular neighborhood analysis was applied and a mean value was calculated per raster cell.

After running the Focal Statistics tool, 2-foot contours were generated from the filtered DEM. To reduce file size and improve performance, the contours were generalized further using the Smooth Line tool in ArcGIS. A smoothing algorithm type of Polynomial Approximation with Exponential Kernel (PAEK) and a smoothing tolerance of 20 feet was selected in the Smooth Line tool parameter options.

Finally, after executing both generalization tools (Focal Statistics and Smooth Line), all lines less than 25 feet in length were omitted from the final output.

Please note: The 2-foot contours are intended to be used for general reference and cartographic purposes only and should not be used for analysis purposes.

This part of USGS Data Series 935 (Cochrane, 2014) presents bathymetry and topography data for the Offshore of Seattle, California, map area, a part of the Southern Salish Sea Habitat Map Series. The data for this map area are a combination of topography extracted from a pre-existing Digital Elevation Model (DEM) merged with bathymetry data that were collected by the National Oceanic and Atmospheric Administration (NOAA) using multibeam sonar systems. The merged data are available for download in a single zip file (BathyTopo_OffshoreSeattle.zip).

1ft contours along the City of Seattle shoreline derived from Lidar captured in 2021. Contour lines display at 1ft, 5ft and 20ft intervals dependent on scale.Development Detail:This vector tile service includes topographic contour lines representing elevation at 1-foot intervals within the City of Seattle shoreline area.The contours were derived from a bare earth - digital elevation model (DEM) with a pixel resolution of 1.5 feet. The lidar data that created the DEM were collected by NV5 Geospatial over the spring and summer months of 2021 and provided to the city by King County in 2022.The DEM used to generate the contours was filtered using the Focal Statistics tool in ArcGIS, which served to limit some abrupt changes in cell values. A 3x3 rectangular neighborhood analysis was applied and a mean value was calculated per raster cell.After generating the contours from the generalized raster, all lines less than 25 feet in length were omitted from the final output.Please note: The 1-foot contours are intended to be used for general reference and cartographic purposes only and should not be used for analysis purposes.

The shoreline essentially follows the 8 foot contour line, except where the ortho offered further clarification. That 8 foot contour line matches closest to what NAVD88 shows as "mean high water" (see official definition below) at 7.97 feet. MEAN HIGH WATER (MHW): "A tidal datum. The average of all the high water heights observed over the National Tidal Datum Epoch. For stations with shorter series, simultaneous observational comparisons are made with a control tide station in order to derive the equivalent datum of the National Tidal Datum Epoch." Source "The MHW line along the tidal shoreline is represented by the contour line that is 8.0' above the NAVD 88. The MHW elevation is not necessarily an equipotential (level) surface, but the variation from a level surface is not significant for this project. The determination of MHW is based on 18 yrs of tidal data and represents the latest official National Tidal Epoch of 1960-1978. The Seattle Tide Station (Sta No 944-7130) is located at the downtown ferry terminal." Source: From paper by Nick Bodnar 10/18/1993 Some other definitions regarding these shorelines (from Nick Bodnar, 10/18/1993): LAKES UNION AND WASHINGTON SHORELINE (18.6' above NAVD 88) The approximation of "ordinary high water"; the level of Lk Washington varies from 17.0'-18.6' during the year; the max lake elevation is 18.8' as controlled by Corps of Engineers (COE) at Hiram Chittenden Locks. The NAVD 88 lake elevations have been converted from the U.S. Engineers Datum. This zero of NAVD 88 is 3.25' above the Locks Datum at the common bench mark P-7. The shoreline contour of 18.8' above NAVD 88 should be used from the Locks, upstream through Lk Union and Lk Washington. The COE has performed various studies that show the level of Lk Wash to approximate an equipotential surface that can be represented by a single contour elevation for mapping purposes. OTHER LAKES The shoreline around Green Lake and all other lakes are delimited by the water/land interface as seen on the aerial photography.

Displays data from CARTO.SHORE_LNUpdated as needed.

Layered GeoPDF 7.5 Minute Quadrangle Map. Layers of geospatial data include orthoimagery, roads, grids, geographic names, elevation contours, hydrography, and other selected map features.

These vector contour lines are derived from the 3D Elevation Program using automated and semi-automated processes. They were created to support 1:24,000-scale topographic map products, but are also published in this GIS vector format. Contour intervals are assigned by 7.5-minute quadrangle, so this vector dataset is not visually seamless across quadrangle boundaries. The vector lines have elevation attributes (in feet above mean sea level on NAVD88), but this dataset does not carry line symbols or annotation.

This data layer references data from a high-resolution tree canopy change-detection layer for Seattle, Washington. Tree canopy change was mapped by using remotely sensed data from two time periods (2016 and 2021). Tree canopy was assigned to three classes: 1) no change, 2) gain, and 3) loss. No change represents tree canopy that remained the same from one time period to the next. Gain represents tree canopy that increased or was newly added, from one time period to the next. Loss represents the tree canopy that was removed from one time period to the next. Mapping was carried out using an approach that integrated automated feature extraction with manual edits. Care was taken to ensure that changes to the tree canopy were due to actual change in the land cover as opposed to differences in the remotely sensed data stemming from lighting conditions or image parallax. Direct comparison was possible because land-cover maps from both time periods were created using object-based image analysis (OBIA) and included similar source datasets (LiDAR-derived surface models, multispectral imagery, and thematic GIS inputs). OBIA systems work by grouping pixels into meaningful objects based on their spectral and spatial properties, while taking into account boundaries imposed by existing vector datasets. Within the OBIA environment a rule-based expert system was designed to effectively mimic the process of manual image analysis by incorporating the elements of image interpretation (color/tone, texture, pattern, _location, size, and shape) into the classification process. A series of morphological procedures were employed to insure that the end product is both accurate and cartographically pleasing. No accuracy assessment was conducted, but the dataset was subjected to manual review and correction.University of Vermont Spatial Analysis Laboratory in collaboration with City of Seattle.This dataset consists of City of Seattle Topo Basins areas which cover the following tree canopy categories: Existing tree canopy percent Possible tree canopy - vegetation percent Relative percent change Absolute percent changeFor more information, please see the 2021 Tree Canopy Assessment.

Contours 2ft created from 2001 LIDAR.

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Peat-settlement-prone areas (sites containing peat and organic soils that may settle when the area is developed or the water table is lowered).Peat settlement-prone areas. Peat settlement-prone areas consist of Category I and Category II peat settlement-prone areas that are delineated on Maps A1 through A26, Peat Settlement-prone Area Boundaries Maps, codified at the end of this Chapter 25.09. This parcel-specific delineation is based on the location of the relevant bog or bogs identified in City of Seattle Identified Bogs (Troost 2007) plus a buffer of 50 feet for Category I peat settlement-prone areas or a buffer of 25 feet for Category II peat settlement-prone areas. On parcels larger than 50,000 square feet, the Director may consider a parcel-specific delineation, provided by the applicant, of the peat settlement-prone area boundary on a parcel. Where a parcel-specific delineation conflicts with the Peat Settlement-prone Area Boundaries Maps, the parcel-specific delineation shall apply.For more information about the definition of peat settlement prone areas, see Seattle Municipal Code section 25.09.012, Environmentally Critical Areas (ECA) definitions.Updated as needed.

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Displays areas with potential landslides in the City of Seattle.A polygon feature class showing potential landslide areas. Used to implement and regulate the City of Seattle's Environmentally Critical Areas (ECA) policies. Last updated in 2001 via the Seattle Landslide Study. The original data was created from City of Seattle State Environmental Policy Act (SEPA) maps which table digitized in 1995 by Donald Tubbs. Shannon & Wilson added runoff zones & edge smoothing.Areas with indications of past landslide activity, such as landslide headscarps and sidescarps, hummocky terrain, areas with geologic conditions that can promote earth movement, and areas with signs of potential landsliding, such as springs, groundwater seepage, and bowed or backtilted trees. For more information about the definition of potential landslide areas, see Seattle Municipal Code section 25.09.012, Environmentally Critical Areas (ECA) definitions.Updated as needed.

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