Arc/Info coverage: basins_usa Brief description: NWS forecast basins for contiguous USA & Puerto Rico Note: this documentation also applies to the sub-coverages of basins for individual RFCs Last coverage update: 11 May 2000 Last documentation update: 11 May 2000 ---------------------------------------------------------------------- Creation start date: Oct 1998 Type (raster/vector): vector Data structure (point/line/poly/other): polygons and annotation Source resolution or scale:unknown for non-IHABBS basins, 15 arc-sec for IHABBS basins Source agency: NWS (various RFCs via NOHRSC) Data acquisition date: Various; 1998 - 2000 for IHABBS, pre-1998 for non-IHABBS Source agency contact: Jason Seifert Source agency phone: (952)361-6610 x228 Source agency e-mail: seifert@nws.gov Source agency WWW address: http://www.nohrsc.nws.gov Source format: mixed digital files Projection: Geographic coordinates Coordinate units: Decimal degrees Projection parameters: NA Ellipsoid: WGS84 Vertical datum: Horizontal accuracy: unknown Vertical accuracy: NA Westmost longitude: -124.142 Eastmost longitude: -65.820 Southmost latitude: 18.040 Northmost latitude: 52.870 Data dictionary: Field name Data type Units Comments ---------- --------- ----- -------- AREA 8F NA PERIMETER 8F NA BASINS_USA# 4B NA BASINS_USA-ID 4B NA SHEF_ID 9C NA Shef ID for the associated basin RFC 5C NA River Forecast Center acronym HUC 16C NA Hydrologic Unit Code CWA 3C NA County Warning Area FCST_GP 5C NA Forecast Group CH5_ID 5C NA COMS Handbook 5 ID for outlet point TYPE 1C NA Pt type:'f'=forecast, or 'd'=datapoint DESCRIPTION 80C NA English Name (ie Rocky Creek at Marion) ATTRIBUTE 40C NA User-defined attributes. May be used by the user for any purpose. USER_LAT_OUT 16N DD Discharge point latitude USER_LNG_OUT 16N DD Discharge point longitude ADJ_LAT_OUT 16N DD Discharge point latitude - adjusted ADJ_LNG_OUT 16N DD Discharge point longitude - adjusted ROR_ELEVATION 16I feet "rain-on-reservoir" basin elevation INCLUDES_NCA 1C NA Flag indicating whether basin contains any non_contributing areas LCL_NCA 16N miles Non-contributing area in square miles LCL_AREA 16N miles TOTAL_AREA 16N miles Drainage basin area in square miles ELEV_ZONES 1I NA Number of elevation zones ZONE1 16I feet Min elevation of (lowest) zone ZONE2 16I feet Min elevation of second zone ZONE3 16I feet Min elevation of third zone ZONE4 16I feet Min elevation of fourth zone ZONE5 16I feet Min elevation of fifth zone ZONE6 16I feet Min elevation of (highest) zone ELEV_DCHARGE 16I feet Elevation of discharge point Notable features: ------------------- There are 82 polygons with SHEF_ID fields beginning with XX_NCA which are interior polygons created during BUILD. They are not forecast basins, but are "Non-Contributing Areas". PROCESSING HISTORY: A. Coverage creation (Jason Seifert 981117) Compiled in Arc/Info using whatever format of the most recent data were available for each region (RFC). IHABBS (Integrated Hydrologic Automated Basin Boundary System) generated basins were received in .gen/.att format (ARC/INFO generate and associated text attributes) from AB, CN, LM, MA, NE, and WG. The remaining source data were digitized by RFCs using various map sources and software packages. Some data were digitized at NOHRSC prior to 1994. Accuracy and precision from one region to another is highly variable. Basins for some regions are extremely crude and not highly accurate. At NOHRSC we manually imported and edited the data from each region to correct errors and remove all edge-matching and "sliver polygon" problems. The "truth" against which the edited product was compared with was the previous year's (1998) basin coverage and the IHABBS-derived RFC boundary coverage. Review comments from staff at NOHRSC and input from RFCs were used in resolving remaining discrepancies. Our intent and expectation is to improve this coverage through the increased use of IHABBS and further integration of IHABBS-generated basin boundaries. Some fields (specifically, the elevation attributes for all RFCs and the DESCRIPTION attributes for the non-IHABBS RFCs) were populated using data received separately from basin boundary data or gleaned from the 1998 gisrs database at NOHRSC. These values were matched to the appropriate basins using the SHEF_ID as a unique identifier. Instances of mismatches or missing data were rectified on an RFC-by-RFC basis. Consequently, complete data sets exist for SHEF_ID, RFC, and elevation fields. A complete data set exists for DESCRIPTION with the notable exception of basins in SERFC. Some of these "basins" are actually flood zones or water management districts with no corresponding english basin name. (JMS, 18 November 1998). B. Notable features The coverage contains 4615 polygons Forecast XX_NCA RFC Basins Polys Total ABRFC 343 343 CBRFC 240 2 242 CNRFC 124 124 LMRFC 469 4 473 MARFC 162 162 MBRFC 711 38 749 NCRFC 776 15 791 NERFC 136 2 138 NWRFC 167 5 172 OHRFC 475 475 SERFC 347 1 348 WGRFC 583 15 598 ----- ----- ----- 4533 82 4615 C. Update history Basin Update (Jason Seifert and David Bitner 000725) Newly updated basin layers were sent to NOHRSC from 5 RFCs (CBRFC, LMRFC, NERFC, SERFC, and WGRFC). All 5 basin updates were generated using IHABBS. These basins were integrated into the national basin dataset after insuring that the basin boundaries matched the RFC boundary. These new basins have the FCST_GP populated where designated by the RFC using IHABBS. XX_NCA attributes were assigned in these 5 RFCs where applicable. All basins have complete attributes for SHEF_ID, RFC, and DESCRIPTION fields.