onemap_prod.SDEADMIN.huncrb

Title: onemap_prod.SDEADMIN.huncrb_poly

Abstract:

The USDA-Natural Resources Conservation Service, Raleigh Office in cooperation with the NC Center for Geographic Information & Analysis, and the NC Dept. of Environment, Health and Natural Resources, Division of Water Quality developed the Hydrologic Units-North Carolina digital data to track resource and conservation activities in the state's river basins and subbasins. Using the 14-digit hyrologic unit code the regional, subregional, accounting, cataloging, NRCS sub-unit, and NRCS reporting unit boundaries id's are recorded. The area attributes allow the user to see hydrologic unit, river basin and subbasin levels of geography. This River Basins file was produced from the Hydrologic Units data and identifies the major NC river basins.

Supplemental_Information:

Data from the protected and critical watersheds layer for the state was used during the development of the HU boundaries. This coverage supersedes data on past versions, particularly the cama24.hu coverage, which was completed as a preliminary to this statewide version. Some boundaries may have changed between the two versions. There are two additional coverages which were generated from this data, the huncrb-river basins; and huncsb-subbasins files. See the cross references section for details.
The following is an excerpt from the "North Carolina Hydrologic Unit River Basin Study," USDA, Natural Resources Conservation Service, November 1995. Under the sponsorship of the Water Resources Council, a nationally uniform hydrologic unit system was developed in 1974 by the US Geological Survey's Office of Water Data Coordination. This system divides the country into 21 regions, 222 subregions, 352 accounting units, and 2,149 cataloging units, based on surface hydrologic features. A hierarchical code consisting of two digits for each of the above four levels combine to form an eight-digit hydrologic unit. The hydrologic unit system is used to identify any hydrologic area of interest. An eight-digit hydrologic unit generally covers 700 or more square miles. In 1978, the USDA-Natural Resources Conservation Service (NRCS) issued a policy that all resource inventories and surveys were to be coded with and capable of being retrieved by hydrologic unit codes (HUCs). At about the same time, NRCS initiated a national program to further subdivide HUCs into watershed-sized areas (nominally 250,000 acres, or 390 square miles) for use in water resource planning. An extension of three digits was added to the eight-digit HUC to designate sub-watersheds, thus forming elevin-digit HUCs. This 1995 Hydrologic Unit (HU) Study divides the state river basins and subbasins into smaller fourteen-digit hydrologic units that will be useful in targeting project activities, resource inventories, and reporting conservation activities. These fourteen-digit hydrologic units of approximately 4,000 acres (6 sqare miles) to 50,000 acres (78 square miles) are small enough in size to be useful as a planning and reporting tool for the USDA-Natural Resources Conservation Service (NRCS) and other government and state agencies. This 1995 fourteen-digit HU map will replace the 1974 eight- digit HU map [U.S. Water Resource Council (WRC)] and the 1978 NRCS eleven-digit HU map as the locating tool for planning in NRCS. The 1995 HU map were produced using 7.5 minute USGS quadrangle base maps (1:24,000 scale).

14-digit number breakdown:
Assigned by US Water     Subunit     Reporting Unit (established
Resource Council       (1978 NRCS)   during this study)
|---------------------|----------|--------|
0  3  0  6  0  1  0  1  0  1  0    0  1  0
|----|----|-----|-----|
|    |    |     |
|    |    |      Cataloging Unit Boundary
|    |     Accounting Unit Boundary
|     Subregional Boundary
Regional Boundary

NOTE: The subbasin 6-digit code (SUBBASIN#) was developed independently from the hydrologic unit codes, from an entirely different numbering system. (Example of code: 03-03-01.) The first two numbers identify the river basin designations adopted by the Environmental Protection Agency. (Date of source: 1974.) Subbasin boundaries were added within individual river basin boundaries (by the office that is now known as the Division of Water Quality, Water Quality Planning Section). Sequential numbers (example -01) were added by DWQ to the first four-digit EPA code to give each subbasin a unique six-digit identifier. (Each subbasin incorporates three or more hydrologic units. The subbasin boundaries have been modified to be coincident with the hydrologic unit boundaries.) Contact Alan Clark at DWQ for more information on the subbasin# code (733-5083, extension 570).

system filename: huncrb     file size = 0.8 mb
(huncrb and huncsb need to be updated whenever hunc is
updated).

Revisions and updates to this layer include:
3.) filename: huncrb1298  The December 1998 update to this layer
consisted of projecting the data from NAD27 datum, State Plane
projection, units of measure feet TO: NAD83 DATUM, State Plane
PROJECTION, UNITS OF MEASURE METERS.  This was done to comply with
the NC Geographic Information Coordinating Council's "Statement of
Direction for North Carolina Corporate Geographic Database
Horizontal Reference, Datum and Unit of Measure".  This reprojecting
was done in various ways depending on the data type and content.
Vector data was projected using the 'project' command in ESRI's Arc
software and topology was cleaned and built based on coverage needs.
Raster data was projected using ESRI's Grid module and various steps
as applicable.

2.) filename: huncrb496   The April 15, 1996 update replaced
the old nc.rivbasin file which was a general reference layer only.
It is archived under the nc.rivbasin name.  The huncrb496 was
created in late 1996, but backdated to reflect the data currency
date of the Hydologic Units file.

1.) filename: rivbasin89  (previously called nc.rivbasin)
This file was created in the late 80s to assist in
identifying the major river basins in North Carolina.  This
data was for display purposes only, ie. locator maps, since
its scale is 1:1,000,000. This file contains ABRV (CHO)
river basin name abbreviation; and, NAME (CHOWAN) attributes
in the PAT.  The AAT contains system default attributes only.
This file was replaced with the huncrb river basins file
from the hydrologic (hunc) units file boundaries at 1:24,000-scale.

Range of values
Minimum:	30247.796
Maximum:	2156434.000
Units:	Feet
Resolution:	0.000001

Range of values

Minimum:

30247.796

Maximum:

2156434.000

Units:

Feet

Resolution:

0.000001

Range of values
Minimum:	1
Maximum:	275

Range of values

Minimum:

Maximum:

275

Range of values
Minimum:	1
Maximum:	275

Range of values

Minimum:

Maximum:

275

Range of values
Minimum:	1
Maximum:	19

Range of values

Minimum:

Maximum:

Range of values
Minimum:	1
Maximum:	18

Range of values

Minimum:

Maximum:

Range of values
Minimum:	519.369
Maximum:	242634.891
Units:	meters
Resolution:	0.000001

Range of values

Minimum:

519.369

Maximum:

242634.891

Units:

meters

Resolution:

0.000001

Range of values
Minimum:	1
Maximum:	292

Range of values

Minimum:

Maximum:

292

Range of values
Minimum:	1
Maximum:	4679

Range of values

Minimum:

Maximum:

4679

HUNCRB.PAT Polygon Attribute Table COLUMN ITEM NAME WIDTH OUTPUT TYPE DEC DESCRIPTION 1 AREA 4 12 F 3 Total area in square meters 5 PERIMETER 4 12 F 3 Total perimeter in linear meters 9 HUNCRB# 4 5 B - Polygon internal ID number 13 HUNCRB-ID 4 5 B - Polygon user ID number 88 RIVBASIN-ABRV 8 8 C - River basin abbreviation 96 RIVBASIN-NAME 20 20 C - River basin name HUNCRB.AAT Arc Attribute Table COLUMN ITEM NAME WIDTH OUTPUT TYPE DEC DESCRIPTION 1 FNODE# 4 5 B - From-node id of linear feature 5 TNODE# 4 5 B - To-node id of linear feature 9 LPOLY# 4 5 B - Left-side polygon id of linear feature 13 RPOLY# 4 5 B - Right-side polygon id of linear feature 17 LENGTH 4 12 F 3 Length of linear feature in meters 21 HUNCRB# 4 5 B - Internal id number 25 HUNCRB-ID 4 5 B - Internal id number

USDA Natural Resources Conservation Service Director, Richard A. Gallo USDA Natural Resources Conservation Staff, Sherman Biggerstaff 4405 Bland Road Raleigh, NC 27609 DENR-Div. of Water Quality - Water Quality Planning Section Director, Steve Tedder DENR-Water Quality Section-Water Quality Planning Staff, Alan Clark 512 N. Salisbury Street Raleigh, NC 27611 North Carolina Center for Geographic Information & Analysis 301 North Wilmington Street, Suite 700 Raleigh, NC 27601-2825

onemap_prod.SDEADMIN.huncrb_poly

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