GroundWater Markup Language Specification v. 1.0

Éric Boisvert 1, Boyan Brodaric2

1 Commission géologique du Canada division de Québec, Secteur des sciences de la Terre, Ressources naturelles Canada. 490 de la Couronne, Québec, QC, Canada

2 Geological Survey of Canada Central division, Earth Sciences Secteur, Natural Resources Canada, 615 Booth Street, Ottawa, ON, Canada


This document is a detailed description of GroundWater Markup Language (GWML). GWML is a GML (Geography Markup Language) application to exchange groundwater related information. It is an extension of another GML application - GeoSciML - designed to exchange geoscience (essentially geology) information (Duffy and Sen 2005). Therefore, GWML also borrows from Observation and Measurements (O&M : OGC 07-022r1) and Sampling Features (OGC 07-002r3) specifications. A more detailed list of conformances is given below.

GWML's scope is the geological aspect of groundwater, and technical details of wells and groundwater measurements. It covers, amongst other aspects:

  • Aquifers and other kinds of HydrogeologicUnit
  • Water Quantity, Flow system, Reservoir and Budget.
  • Water Quality (natural quality), suspended, dissolved and colloidal content
  • Water Wells, wells components, such as screens and casing

It does not cover water quality beyond natural quality, for instance contamination by human activity and remediation is not specifically covered, but handled generically. Suface water is not modelled in any details (but just as very generic classes). Geochemistry is not modelled beyond result reporting using O&M, which exclude explicit details about sample manipulations, methodologies, etc. But this can be covered generically though O&M.

GWML has been designed according to the ISO-19103, ISO-19118 and ISO-19136 following the best practices developed in GeoSciML. This methodology allows inserting this development in the larger OGC framework and SOA architecture implied by such standards.

The methodology to create this model involves creating a UML representation, following the ISO profiles (ISO 19103), and importing all the external models that can be reused in the context of GWML. The UML representation can be converted into a W3C XSD schemas following the ISO-19118 guidelines, which prescribe a series of standard XSD constructs to represent all elements permitted in the ISO UML profile. The XSD schema defines the XML structure of a GML application and provides the validations mechanism to assess the syntactic conformance of a XML document. The XSD representation is a 1:1 equivalent of the UML representation; therefore the UML model is also the official documentation of the XSD schema. The UML model, stored in Enterprise Architect is available from here Zip included archived documents

This document is a complete listing of all the classes provided by GWML. GeoSciML, Observations and Measurements and Sampling Features, Metadata specific classes are not described in this document, and the reader should refer to specific documentation.


The GroundWater Markup Language Specification 1.0 is fully documented. The following page provide a complete documentation set for GWML.

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Message GWML 2.2 is now an official OGC standard !
GWML 2.2 is a new version aligned to Observation and Measurement 2.0 and GeoSciML 4.1


GWML is conformant to the following standards and best practices:

  • IETF RFC 2396, Uniform Resource Identifiers (URI): Generic Syntax. (August 1998)
  • GeoSciML 2008, GeoScience Markup Language, IUGS Commission for Geoscience Information,
  • ISO 1000:1994, SI units and recommendations for the use of their multiples and of certain other units
  • ISO 8601:2004, Data elements and interchange formats - Information interchange Representation of dates and times
  • ISO/IEC 11404:1996, Information technology - Programming languages, their environments and system software interfaces Language-independent datatypes
  • ISO 19101:2003, Geographic Information--ReferenceModel
  • ISO/TS 19103:2006, Geographic Information - Conceptual schema language ISO 19107:2003, Geographic Information - Spatial schema
  • ISO 19108:2002, Geographic Information - Temporal schema
  • ISO 19109:2006, Geographic Information - Rules for application schemas
  • ISO 19110:2006 , Geographic Information - Feature cataloguing methodology
  • ISO 19115:2003, Geographic Information - Metadata
  • ISO 19118:2005, Geographic Information - Encoding
  • ISO 19123:2005, Geographic Information - Coverages
  • ISO DIS 19136:2006, Geographic Information - Geography Markup Language
  • ISO/FDTS 19139:2006, Geographic Information - Metadata - XML schema implementation
  • ISO/IEC 19757-3:2006, Information technology -Document Schema Definition Language (DSDL) -Part 3: Rule-based validation -Schematron
  • OpenGIS(r) Engineering Specification Observations and Measurements - Part 2: Sampling Features, OGC document 07-002
  • OpenGIS(r) Engineering Specification Sensor Model Language, OGC document 07-001
  • OpenGIS(r) Engineering Specification Sensor Observation Service, OGC document 06-009
  • OpenGIS(r) Engineering Specification Transducer Markup Language, OGC document 06-010
  • OpenGIS(r) Interoperability Program Report SWE Common, OGC document 07-003
  • UCUM, Unified Code for Units of Measure, Schadow, G. and McDonald, C. J. (eds.),
  • W3C XLink, XML Linking Language (XLink) Version 1.0. W3C Recommendation (27 June 2001)
  • W3C XML, Extensible Markup Language (XML) 1.0 (Second Edition), W3C Recommendation (6 October 2000)
  • W3C XML Namespaces, Namespaces in XML. W3C Recommendation (14 January 1999)
  • W3C XML Schema Part 1, XML Schema Part 1: Structures. W3C Recommendation (2 May 2001)
  • W3C XML Schema Part 2, XML Schema Part 2: Datatypes. W3C Recommendation (2 May 2001)