MassGIS has produced a statewide digital datalayer of the 27 major drainage basins of Massachusetts as defined by the USGS Water Resources Division and the MA Water Resources Commission. In ArcSDE are two layers - MAJBAS_ARC and MAJBAS_POLY.
A set of 1:24,000 USGS paper quad sheets was carefully delineated with approximately 1800 minor or sub- drainage basins. This work was produced over the past 20 years by the USGS-WRD. Generally, the contours on the quads are the primary guide to basin boundaries. Often the 'mouth' of a basin is marked at the site of a stream gauging station, which can be different from the strict geographic location of the mouth.
The major basins were produced from the sub-basins using the Arc/INFO Dissolve command. This removed all lines except boundaries between major basins. This was possible because the Major Basin # is encrypted in the Sub-Basin-ID
The resulting Massachusetts internal major basin boundaries were then Appended to the state outline and shoreline, and processed to result in a statewide polygon datalayer, which is a digital facsimile of the Massachusetts Water Resources Commission official Massachusetts Drainage Basins Map.
All sub-basins on the manuscripts were digitized (refer to SUB-BASINS Datalayer description). Due to good manuscript quality, including the visual edgematching of the 189 sheets, digitizing and edgematching was straightforward. The manuscript author was consulted on the minor errors and ambiguities that were discovered.
The polygon attribute table contains these items:
|AREA_ACRES||Acreage of each polygon|
|BAS_ID||Major Basin numbers 1 to 27|
|NAME||Major Basin name|
KEY TO THE MAJOR BASIN NUMBERING SYSTEM:
BASIN # BASIN NAME
14 SuAsCo (Sudbury-Assabet-Concord; formerly Concord)
18 North Coastal
19 Boston Harbor
21 South Coastal
22 Cape Cod
24 Buzzards Bay
26 Narragansett Bay & Mt. Hope Bay Shore
27 Ten Mile
The Major Basin.arc attribute table contains an item called OUTLINE. This enables the state border and shoreline to be differentiated from interior lines. This enables a different line type to be used for the outline of the state.
In ArcSDE the annotation is stored in the layer MAJBAS_ANNO_BASIN.
Each panel was plotted at 1:48,000 and compared to the digitizing manuscript.
MassGIS is maintaining this datalayer. In February 2002 the DEP GIS Group modified some linework within the USGS Woronoco (#33) Quadrangle to synchronize the major basin divide with changes in the DEP Surface Water Supply Protection Area datalayers (Zone A, B, C) and Sub-basin tiles. In May 2002 the DEP GIS Group revised the N. Coastal/Ipswich basin boundary in Wenham. In March 2003 linework was updated along the Westfield/Connecticut and N. Coastal/Ipswich boundaries.
|Date published:||March 1, 2003|
|Last updated:||March 1, 2003|