Download
1 / 32
320 likes | 447 Views
New Documents for the National Hydrography Dataset. National Hydrography Dataset Feature Catalog Based on 1:24,000-scale USGS Topographic Map Content U.S. Department of the Interior U.S. Geological Survey. AREA OF COMPLEX CHANNELS – Glacial outwash in Alaska. AREA TO BE SUBMERGED
E N D
National Hydrography Dataset Feature Catalog Based on 1:24,000-scale USGS Topographic Map Content U.S. Department of the Interior U.S. Geological Survey
AREA TO BE SUBMERGED Dam under construction will create Lake Nighthorse in CO
Los Angeles Aqueduct CANAL/DITCH – C/D Type = Aqueduct PIPELINE – Pipeline Type = Aqueduct; Aboveground Both of these features function as an aqueduct – “A structure designed to transportdomestic or industrial water from a supply source to a distribution point, often by gravity” However, they have different forms. One is an “artificial open waterway…” and the other is a “closed conduit…”
San Francisco/San Pablo/Suisun Bay ESTUARY Looking south west towards the Pacific Ocean
San Francisco/San Pablo/Suisun Bay Estuary – currently coded as SEA/OCEAN (grey-blue) in the NHD. New guidance for delineation of ESTUARY would separate the ESTUARY from SEA/OCEAN as shown by the solid green line (approximately the Golden Gate Bridge). Pink straight line indicates line of sight from the photo. The red line in the Pacific Ocean is the three-mile limit. This is the preferred limit for SEA/OCEAN – current limit of SEA/OCEAN is the edge of the USGS quadrangle maps – hence the straight lines.
Hassayampa River In the NHD, WASHES are delineated only as areas. If there is no perennial channel within the wash, ARTIFICIAL PATHS are added to allow flow through the network.
National Hydro Dataset Data Dictionary Data Model version 1.06 U.S. Department of the Interior U.S. Geological Survey
National Hydro Database Stewardship Handbook Review Draft Please send comments to: Keven Roth kevenroth@yahoo.com U.S. Department of the Interior U.S. Geological Survey
Things to come Metadata
Data in Previous Slide shows edits (in pink) in 11110104 Metadata record for the updates shown in previous slide is: “Update high-resolution NHD for Benton and Washington Counties, AR from 25ft LIDAR derived DEM and 6in and 12in ortho-imagery, dated 2004 and 2006. This process started with current high resolution USGS NHD geodatabase files. These data were downloaded, extracted and reprojected to NAD 83 State Plane Arkansas N. Next, the NRCS 10-digit Hydrologic Unit Code (HUC) boundary was obtained from GeoStor <http://www.geostor.arkansas.gov/>, Arkansas official geodata clearinghouse. The HUC boundary was projected to the State Plane projection and used, in part, to determine the true spatial extent of 8-digit HUC (Sub-basin) boundaries with Benton and Washington Counties. Next, hydrological analyses were performed on a 25ft LIDAR derived DEM using ArcInfo 9.1 hydrologic tools. The 25ft DEM was generated by the Center for Advanced Spatial Technologies (CAST) at the University of Arkansas using a bare earth point cloud obtained from Landair Mapping, Inc as part of the August 2004 LIDAR acquisition (Washington & Benton Counties, AR) coordinated by John McLarty, Elizabeth Bowen, Brian Culpepper, and Dr. Jack Cothren of the Northwest Arkansas Imagery Task Force. The purpose of hydrological analysis was to determine flow accumulation and direction throughout Benton and Washington Counties, thus providing an indicator as to the location of undocumented streams. Finally high resolution 2004 and 2006 true-color orthoimages, distributed by the Northwest Arkansas Regional Planning Commission and co-operative partners, were added to ArcMap 9.1 project file along with NHD, HUC high resolution boundaries and DEM flowpaths. Navigating between all 4 datasets, the 1D and 2D NHD features were updated to reflect temporal changes. Presence of 2D features were determined if the feature could be clearly seen to have area in either the 2004 or 2006 orthoimages when the screen was set to a scale of 1:4,800. Once identified, a polygon boundary was drawn, or updated, to show the feature at its high water mark (its greatest area in either of the available orthoimages). 1D features were identified using a combination of flow accumulation values (determined by DEM hydrological analyses) and supporting visual data in the orthoimagery (i.e. location of vegetative stream buffers), and drawn or updated accordingly. Consultation with the USGS concluded that undocumented streams would most likely occur in areas where the flow accumulation value was >2000 (greater than 2000 upslope pixels); therefore, areas having a value of <2000 were rarely considered for possible streams. All new 1D and 2D features were assigned feature codes (fcodes) in accordance to USGS NHD definitions, along with new reach codes.”
