Status and Plan

Canada's major drainage areas In all, 1226 drainage areas or NHN Work Units (WU) are currently necessary to cover the entire Canadian landmass. Of this number, NHN data is now available for 1211 WU. Corresponding NHN data are produced via various production processes and are periodically published on the GeoBase Web Portal.

Initial NHN Production

In 2007, the first available NHN data were produced by the province of British Columbia and via contracts granted to the Canadian industry. In all, 287 WUs compliant with the NHN Completeness Level 4 (NHN-CL4) were produced. Following this initial production, a review of the NHN Implementation Strategy was called for due to the complexity in producing from the start NHN data compliant with the NHN-CL4. Read more on the NHN Implementation Strategy.

National Coverage

In early 2008, following the review of the NHN Implementation Strategy, the automatic production of NHN data using Natural Resources Canada's (NRCan) digital topographic data was initiated. All WUs for which NRCan source data was available have since been produced, covering over 95% of the Canadian territory.

To date, only 15 WUs located in Canada's north, in the Hudson Bay and in the James Bay remain to be produced to cover the entire Canadian landmass. NHN data for these WUs will gradually be produced as NRCan's source data becomes available. It is expected that the NHN national coverage will be completed in the coming year.

Provincial/Territorial Partnerships

Partnership agreements for the production of NHN data using provincial source data have been concluded with the provinces of Ontario and Quebec. These agreements aim the creation of NHN-CL2 data in the south of these provinces. In fact nearly all of the NHN-provincial data covering the south of Ontario is now available; only one WU remains to be completed. The implementation of Quebec NHN-provincial data should start in the coming year.

An agreement with the Yukon Territory aiming the upgrade of currently available NHN data, created using NRCan topographic data, to the NHN-CL3 is also in place.

Also, discussions are taking place with the province of Manitoba to replace currently available NHN data with data compliant with the NHN-CL3 created using Manitoba provincial data in the south of the province and NRCan data in the north.

As a result, current NHN data created using NRCan topographic data will gradually be replaced by more current and more accurate NHN data and/or of a superior completeness level in these provinces and territory.

NHN data production using provincial data can have for effect of increasing the number of WUs required to cover the Canadian territory, where in doing so, some WUs may temporarily be divided (and renamed) at the limit of the territories covered by the partnership agreements. Temporarily divided WUs will eventually be subject to a merge as part of a future NHN data alignment task on both sides of these territory limits.

Canada/USA Partnership

A project of creating common and complete Canada/USA trans-boundary drainage areas spanning the international boundary is also in progress. This project is implemented with the collaboration of the following partners:

The creation of trans-boundary drainage areas is carried-out in 3 main phases, being the limit definitions of trans-boundary drainage areas, the NHN and NHD (USGS National Hydrography Dataset) hydro data alignment and finally the creation of hydrographic data in both the NHN and NHD models.

In total, 118 NHN Work Units straddle the Canada/USA international boundary. Of this number, 76 are now available on the GeoBase Web portal. It is expected that this initial trans-boundary production will be completed sometime in the summer of 2012.

This production also has for effect of increasing the number of WUs required to cover the Canadian territory and consequently modify NHN dataset identifiers of trans-boundary WUs.

Updating

NHN datasets available on the GeoBase Web portal may also be subject to a data update process when all of the original source data used in the creation of the initial NHN have been updated. Such data update normally does not modify the number of WUs nor NHN dataset identifiers, but may cause modifications to WU limits in order to adjust them to the up-dated source data. Updated NHN data is compliant with the NHN-CL2. It is planned that in the course of 2012, some updated NHN WUs will be made available.

Completeness Level Upgrade

A process of upgrading the completeness level of a number of NHN datasets to bring them compliant with the NHN-CL3 is in progress. To do so, a few WUs are being produced via an internal NRCan process in 2011-2012, and as of April 2012, a more important production will be implemented via contracts to the Canadian industry. Several current NHN WUs will thus gradually be replaced by NHN-CL3 data in the coming years.

Re-generation

An available NHN dataset adjacent to a WU that has undergone one of the above production activities may in turn need to be re-generated and re-published if its WU limit was modified to make it coincide with that of the dataset processed under one of the above activities. In some cases, NHN dataset identifiers for these adjacent WUs may have been modified either to assign them a temporary dataset identifier (for WUs temporarily divided at the territory limit covered by a provincial partnership agreement) or to be in compliance with a new Water Survey of Canada Sub-Sub-Drainage area nomenclature.

The correction of an NHN data anomaly also initiates a re-generation and re-publication of a NHN dataset.

The NHN Implementation Strategy

The NHN Implementation Strategy is thus realized by the addition, the update, the upgrade or the replacement of NHN datasets on the GeoBase Web portal. Thus far, the NHN implementation was carried-out as follow:

October 1, 2007: Publication of 287 NHN drainage areas accounting for about 20% of the Canadian landmass, namely: the 246 NHN-CL4 Work Units or drainage areas produced by British Columbia; and the 41 NHN-CL4 Work Units located in Manitoba (28), Saskatchewan (2), Yukon (6) and Newfoundland-and-Labrador (5) produced under the initial production process from Natural Resources Canada.
March 20, 2008: Publication of 552 new NHN-CL1 and NHN-CL2 datasets in accordance with the new NHN Implementation Strategy, increasing the total number of available NHN datasets on the GeoBase portal to 839.
June 1, 2008: Publication of 63 new NHN-CL1 and NHN-CL2 datasets increasing the total number of available NHN datasets on the GeoBase portal to 902, accounting for about 70% of the Canadian landmass.
December 15, 2008: Publication of 140 new NHN-CL1 and NHN-CL2 datasets increasing the total number of available NHN datasets on the GeoBase portal to 1042, accounting for about 85% of the Canadian landmass.
May 15, 2009: Publication of 50 new NHN-CL1 and NHN-CL2 datasets increasing the total number of available NHN datasets on the GeoBase portal to 1092, accounting for more than 90% of the Canadian landmass. This publication provides all NHN datasets that have undergone a particular processing (special cases) as well as those for which source data have recently been updated. The particular processing referred to here affects only NHN-CL1 and NHN-CL2 datasets for which the automated processing have required an extra interactive processing phase.
December 10, 2009 - FIRST NATIONAL COVERAGE: Publication of 38 new NHN-CL1 (13) and NHN-CL2 (25) datasets increasing the total number of available NHN datasets on the GeoBase portal to 1130, and achieving the first NHN national coverage (see index map below). This publication notably provides NHN datasets issued from recent cartographic data production in the Hudson Bay low lands area and in northern Canada. On February 15, 2010, 4 new NHN-CL1 datasets were added to the first national coverage, increasing the total number of NHN datasets available to 1134.
March 1, 2011: Publication of 7 new NHN-CL1 datasets located in Canada's north, of 4 NHN-CL2 datasets created from Ontario provincial data and of 46 Canada/USA trans-boundary NHN datasets. Thus far, NHN data is now available over 95% of the Canadian territory.
June 20, 2011: Publication of 106 NHN-CL2 datasets created from Ontario provincial data and of 12 Canada/USA trans-boundary NHN datasets (note that 2 of these 12 WUs were produced using NHN-CL2 data originating from Ontario provincial data). Thus far, NHN data is now available over 95% of the Canadian territory.
December 14, 2011: Publication of 117 NHN datasets, of which 18 new Canada/USA trans-boundary WUs, 17 (3 of which are included in the 18 Can/US units) NHN-CL2 WUs created from Ontario provincial data, 12 (5 of which are included in the 18 Can/US units) NHN-CL3 WUs, 2 new WUs located in Canada's north, 4 WUs regenerated to fix anomalies in NHN data and 72 WUs regenerated due to a modification of their NHN Work Unit Limits.

NHN Coverage

An index of the available NHN data coverage can be found under section Data/Download/Option1 - Graphical Search of the National Hydro Network.

This index illustrates the availability of NHN data by their NHN completeness level and allows the download of data by graphical search. Areas for which NHN data is not yet produced are identified in white.