Source Data The NHD High Resolution Delineation takes advantage of some of the layers from the DSL Project which involved extensive work to clean up the NHD high resolution flowlines. This effort is the foundation of the NHDHRDV2 products. While the DSL flowline editing methodology was applied to the expansion area in Figure 7, any further additions to the spatial extent of the delineation products will require a significant effort to edit flowlines outside of this zone. Flowlines The flowline layers are used in delineation processing to establish the stream network throughout the landscape. DSL Processed Flowlines name: allstreams Source: DSL Project Description: The NHD high resolution flowlines that have been edited to eliminate network gaps, correct flow direction, and remove coastline. The range of this dataset is depicted in blue in Figure 7. NHD High Resolution Flowlines Layer name: NHDFlowline Source: National Hydrography Dataset Description: The NHD flowlines are downloaded as separate geodatabases based on HUC 4 boundaries. The downloaded geodatabases are saved into separate folders named for each hydrologic region they are a part of (e.g. These layers are used to fill in the areas “NHDH01”). within the processing region that the DSL flowlines do not cover. The processing range of this dataset is depicted in red in Figure 7. Digital Elevation Models (DEM) The DEMs are used to establish the flow paths over the delineation ranges by providing topographic information. DSL Processed DEM name: dem Source: DSL Project Description: The DSL processed DEM is a mosaic of 30m resolution National Elevation Dataset (NED) DEMs. It matches the spatial coverage of the DSL flowlines. Raw NED 30 DEMs Layer name: grdn45w067_1 Source: National Elevation Dataset
Source Data The NHD High Resolution Delineation takes advantage of some of the layers from the DSL Project which involved extensive work to clean up the NHD high resolution flowlines. This effort is the foundation of the NHDHRDV2 products. While the DSL flowline editing methodology was applied to the expansion area in Figure 7, any further additions to the spatial extent of the delineation products will require a significant effort to edit flowlines outside of this zone. Flowlines The flowline layers are used in delineation processing to establish the stream network throughout the landscape. DSL Processed Flowlines name: allstreams Source: DSL Project Description: The NHD high resolution flowlines that have been edited to eliminate network gaps, correct flow direction, and remove coastline. The range of this dataset is depicted in blue in Figure 7. NHD High Resolution Flowlines Layer name: NHDFlowline Source: National Hydrography Dataset Description: The NHD flowlines are downloaded as separate geodatabases based on HUC 4 boundaries. The downloaded geodatabases are saved into separate folders named for each hydrologic region they are a part of (e.g. “NHDH01”). These layers are used to fill in the areas within the processing region that the DSL flowlines do not cover. The processing range of this dataset is depicted in red in Figure 7. Digital Elevation Models (DEM) The DEMs are used to establish the flow paths over the delineation ranges by providing topographic information. DSL Processed DEM name: dem Source: DSL Project Description: The DSL processed DEM is a mosaic of 30m resolution National Elevation Dataset (NED) DEMs. It matches the spatial coverage of the DSL flowlines. Raw NED 30 DEMs Layer name: grdn45w067_1 Source: National Elevation Dataset