Introduction

The Environment Canada Watershed Lookup Service provides an GML [1] encoded web service, which returns geometries for known watershed ID codes.

The Service provides polygon bounding geometries for watersheds as per polygon data obtained from Geogratis [2]. The Service returns record(s) for matching watershed codes with polygon geometry, encoded in GML 3.0.0 [1].

Below is a diagram of how the service derives feature geometry for watershed records.

HTTP Request Rules

The Environment Canada Watershed Lookup Service accepts both HTTP GET and HTTP POST. Keyword parameters may be entered in either case, however value parameters are case sensitive.

EC Watershed Lookup Service Operations

The Service supports two (2) operations

- GetCapabilities

- GetWatershed

GetCapabilities

The purpose of the GetCapabilities operation is to provide general information about the service itself and specific information about the name sources used.

Request parameter	Required/Optional	Description
VERSION=1.0.0	R	Request version
REQUEST=GetCapabilities	R	Request name

See Appendix A for ex ample GetCapabilities requests and responses.

GetWatershed

The purpose of the GetWatershed operation is to return the geometries for a placename inputted by a request.

Request Parameter	Required/Optional	Description
VERSION=1.0.0	R	Request version
REQUEST=GetWatershed	R	Request name
CODE=wx[y[z]]	R	Watershed code, 2, 3, or 4 alphanumeric characters

Below is the content model returned by a GetWatershed response:

See Appendix A for example GetWatershed requests and responses.

The EC Watershed Lookup Service is available at:

http://devgeo.cciw.ca/WatershedLookupServlet/WatershedLookupServlet

An online sample interface to the EC Watershed Lookup is available at:

http://devgeo.cciw.ca/watershed/sample.html

Issues / future work:

- Supporting full polygon line work

- Searching by Drainage Basin name

Appendix A: Example Requests and Responses

Application Schema

The application schema for the GetWatershed response model is located at:

http://devgeo.cciw.ca/schemas/ec/watershed/1.0.0/watershed.xsd

GetCapabilities

Sample request:

http://devgeo.cciw.ca/WatershedLookupServlet/WatershedLookupServlet?version=1.0.0&request=GetCapabilities

GetWatershed

Sample request, searching by major drainage area for watershed code ‘01’

http://devgeo.cciw.ca/WatershedLookupServlet/WatershedLookupServlet?version=1.0.0&request=GetWatershed&code=01

Sample request, searching by sub drainage area for watershed code ‘01E’

http://devgeo.cciw.ca/WatershedLookupServlet/WatershedLookupServlet?version=1.0.0&request=GetWatershed&code=01E

Sample request, searching by sub sub drainage area for watershed code ‘01EH’

http://devgeo.cciw.ca/WatershedLookupServlet/WatershedLookupServlet?version=1.0.0&request=GetWatershed&code=01EH

References

[1] Cox, S., Daisey, P., Lake, R., Portele, C., Whiteside, A., “OpenGIS Implementation Specification #02-023r4: OpenGIS Geography Markup Language (GML) Implementation Specification, version 3.0.0”, 29 January 2003, <http://www.opengis.org/techno/documents/02-023r4.pdf>

[2] GeoGratis, “National Scale Frameworks Hydrology - Drainage Areas, Canada”, June 2003,

<http://geogratis.cgdi.gc.ca/clf/en?action=entrySummary&entryId=13798&entryType=productCollection&keymap=outlineCanada>