This dataset is a subset of the Standard Drainage Area Classification (SDAC) 2003 dataset. It has been subset to the Nelson River drainage area.

The Drainage Areas dataset is largely based on the Water Survey of Canada (WSC) drainage area boundaries at the sub-sub-basin level. The data model supports the derivation, from the Fundamental Drainage Areas (FDA) dataset (sub-sub-basin level), of the WSC and the National Atlas of Canada (NA) (AC) drainage area hierarchies and the data is available in all three schemes. Drainage area definitions for both WSC and Atlas of Canada boundaries were reviewed resulting in some modifications. Larger scale reference data sources were used for further manual boundary adjustments. This dataset has been integrated with other National Scale Frameworks hydrology datasets and is considered a component of the Hydrology Theme.

• Drainage Area
• Hydrography
• Water features
• Watershed

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The Drainage Areas Framework supports three hierarchical classification schemes: the Water Survey of Canada, and the National Atlas of Canada, and Canadian Watersheds. These are identified in their file names by the tags WSC, NA and WSHED, respectively. The Fundamental Drainage Area Framework dataset, canadfda, contains attributes for all three classification schemes as well as the INTERNAL and DIVERSION attributes.

The Water Survey of Canada classification scheme has three levels: Major Drainage Area, Sub-Drainage Area, and Sub-Sub-Drainage Area.  The National Atlas classification scheme has five levels: Ocean Drainage  Area, Major River Basin, Component Basin (of Major River Basin), Sub-Component Basin, and Sub-Sub-Component Basin.

In the WSC and NA schemes, the deepest level (SSDA or SSCB) can be used to derive the higher levels. For convenience the higher levels have been provided. Each level preserves the attributes of the levels above it (i.e. each Sub-Sub-Drainage Area is also coded with its parent Sub-Drainage Area and Major Drainage Area).  

In the Canadian Watershed scheme, there is only one explicit level of hierarchy.  However, with two exceptions, the Canadian Watersheds are compatible with the WSC scheme at the levels of major and sub-drainage areas. For instance, by truncating a watershed code to the first 3 characters, one obtains the code for the corresponding WSC sub-drainage area.  

Attribute_Accuracy_Report: Where applicable, attribute data were symbolized on-screen or as hard copy plots and inspected. Attribute data integrity was also verified using automated procedures to check for anomalies such as duplication of data in fields requiring unique vales and incorrect feature coding.

Logical_Consistency_Report:Using ESRI ArcGIS automated reporting, the following were tested for all features: a) arcs begin or end at nodes b) arcs connect to each other at nodes c) arcs do not extend past nodes d) polygons are closed e) All points, lines and polygons are topologically related. Where these statements for arc/node relationships were found to be false, manual editing was performed until automated reporting showed all to be true. Upon completion of all quality control procedures the entirety of this dataset is considered as topologically clean.

Completeness_Report: The Drainage Areas Framework supports three hierarchical classification schemes: the Water Survey of Canada, and the National Atlas of Canada, and Canadian Watersheds. These are identified in their file names by the tags WSC, NA and WSHED, respectively. The Fundamental Drainage Area Framework dataset, canadfda, contains attributes for all three classification schemes as well as the INTERNAL and DIVERSION attributes.

The Water Survey of Canada classification scheme has three levels: Major Drainage Area, Sub-Drainage Area, and Sub-Sub-Drainage Area.  

The National Atlas classification scheme has five levels: Ocean Drainage Area, Major River Basin, Component Basin (of Major River Basin), Sub-Component Basin, and Sub-Sub-Component Basin. In the WSC and NA schemes, the deepest level (SSDA or SSCB) can be used to derive the higher levels. For convenience the higher levels have been provided. Each level preserves the attributes of the levels above it (i.e. each Sub-Sub-Drainage Area is also coded with its parent Sub-Drainage Area and Major Drainage Area).  In the Canadian Watershed scheme, there is only one explicit level of hierarchy.  However, with two exceptions, the Canadian Watersheds are compatible with the WSC scheme at the levels of major and sub-drainage areas. For instance, by truncating a watershed code to the first 3 characters, one obtains the code for the corresponding WSC sub-drainage area.

The National Scale Frameworks Hydrology data consists of area, linear and point geospatial and attribute data for Canada's hydrology at a national scale. It provides a representation of Canada's surface water features, and data completeness reflects the content of the source, the original Vector Map level 0 (VMAP0) revision 4 hydrographic layers, except where revision editing has been performed. Key value-added characteristics include river flow direction, connectivity and the tagging of geographical name keys to selected rivers, lakes and islands included in the Concise Gazetteer of Canada. The product set for the hydrology theme consists of six groupings: Drainage Network Skeleton, Waterbodies, Islands, Drainage Areas, Supplemental Drainage Features (Hydrometric Gauging Stations and Dams) and Cartographic.

The Water Survey of Canada (Environment Canada) has a 3-level hierarchy of drainage areas established in 1927 for the purpose of managing hydrometric stations (recording water levels or rates of flow). This scheme covers the entire landmass of Canada.

The National Atlas Drainage Basin scheme, delineated on a paper map in 1980, was based on classic drainage basins having certain minimum volume of mean annual discharge. (A classic drainage basin is a land area for which all the surface drainage with its boundary converges and exits at a single point.) The National Atlas Drainage Basin scheme effectively excludes coastal drainage areas whose discharge volume does not meet its criterion for inclusion.

In 2006-2007 the Atlas of Canada added a fourth scheme to the drainage areas frameworks. Selected Fundamental Drainage Areas polygons were merged to create a full-country coverage of 595 “Canadian Watersheds” to be used in the broad public dissemination of information on watersheds and water issues.