1. Introduction

The Open Geospatial Consortium (OGC) is releasing this Call for Participation (CFP) to solicit proposals for the _OGC Water Quality Interoperability Experiment (WQ IE). This IE will advance the development of the WaterML 2.0 suite of standards in the area of water quality data. The WQ IE will test interoperability and interconnection of existing Water Quality Data Systems. The participants will identify how to support WaterML 2.0 development in the domain of Water Quality (WQ). This includes enhancement of WQ related taxonomies/ontologies and API identification and usage, with the ultimate goal of both the OGC OGC and the World Meteorological Organization (WMO) endorsement of an international standard and/or best practice for Water Quality data exchange.

The interoperability experiment will be framed by high-level water quality data use cases. For example, data exchange between local jurisdictions and regional or national environmental agencies is a motivating use case. Specific use cases, such as representation of sampled media or measured constituents, are critical to the success of the IE and will be defined as part of the IE.

1.1. OGC Innovation Program Initiative

This initiative is being conducted under the OGC Innovation Program. This program provides a collaborative agile process for solving geospatial challenges. Organizations (sponsors and technology implementers) come together to solve problems, produce prototypes, develop demonstrations, provide best practices, and advance the future of standards. Since 1999 more than 100 initiatives have taken place.

IEs are generally structured to support or extend the standardization work in the OGC and thus the IE participants will coordinate closely with the appropriate OGC Technical Committee Working Groups, such as the Geoscience DWG mentioned above.

1.2. Contact

Answers to this Call are collected with the OGC Innovation Program contact form. Alternatively they can be sent to innovation@ogc.org.

2. Participants and observer organizations

This IE will be open to the general public. Participants will be required to make a resource commitment. Technical experts from non-OGC organizations may be Participants in the IE. Other individuals from non-OGC organizations will be allowed in the IE as Observers. Any OGC member may register as an Observer.

Participants and Observers will join the founding organizations of the IE. Founding organizations are:

  • Bureau de Recherches Géologiques et Minières (BRGM), France

  • Centro de Investigación Ecológica y Aplicaciones Forestales (CREAF), Spain

  • Center for Geospatial Solutions, Lincoln Institute of Land Policy (CGS), USA

  • Federation University Australia, Australia

  • Pole INSIDE - Environmental information systems research center, France

  • United Nations Environmental Programme (UNEP) Global Environment Monitoring System for freshwater (GEMS/Water) Data Centre, Germany

  • United States Geological Survey (USGS), USA

  • United States Environmental Protection Agency (USEPA), USA

  • University of Tartu, Estonia

  • World Meteorological Organization (WMO) HydroHub

2.1. Observer caveats

Official IE Observers will be granted access to the IE project on the OGC Portal. Observer status allows the member or non-member to monitor progress of the given IE, have access to the IE e-mail reflector, access documents as they are posted to the IE folder on the portal, contribute software and/or data to the effort, and so forth. Observer status does not allow the Member or non-member to attend the IE Kickoff meeting, formally comment on documents, or otherwise disrupt the execution of the IE. Interoperability Engineering Reports from the IE will be made available to all OGC members at the end of the IE for review and comment.

3. Scope of the IE

3.1. Background

Since 2008, Members of the OGC/WMO Hydrology Domain Working Group have been developing the WaterML 2.0 standards for the transmission of a broad suite of water information. Interoperability of water quality data is critical to improved management of water resources and depends on the use of common semantics (vocabularies/taxonomies) and technical scenarios.

Furthermore, sharing of water quality data globally and nationally is currently limited. This is likely due to a lack of shared international standards and practices in this area and to the variety and distribution of responsibilities across agencies at national scale in the field of water quality. Some practices do already exist, most commonly on a per country basis (e.g., US WQX, French Sandre, etc.) with the exception of the EU environmental reporting in the field of water (EU WFD/WISE and EIONET-related reporting). However, in most cases those practices are not based on current internationally-agreed semantic and technical interoperability practices (OGC, W3C, RDA).

Establishment of international standards for water quality data is a key activity towards enhancing the availability of water quality information at the global level and increasing the effectiveness of development activities.

The IE will build on:

  • The experience gained and data assets available from existing systems;

  • The OGC Standards Baseline:

    • semantics: WaterML2.0 suite of standards, Observations, Measurements and Samples (OMS),

    • technical: OGC API - Features, OGC SensorThings API, OGC API - EDR;

  • Early attempts applying interoperability best practices in this field (e.g., OGC WaterML-WQ Best practice, 14-003, EU API4INSPIRE project, “A Harmonized Vocabulary For Water Quality” DOI:10.13140/RG.2.1.2490.4404);

  • W3C best practices: (spatial) data on the web best practices, JSON-LD, SOSA/SSN; and

  • Research Data Alliance (RDA) work on observable properties (I-ADOPT).

The participants propose to vet the existing OGC Standards Baseline for common Water Quality data exchange use cases and build consensus with a broad community (WMO, RDA, others) for how to express water quality observation and sampling information.

The interoperability experiment will deliver an Engineering Report (ER) outlining opportunities to use existing technology, update the WaterML2 Best Practice for water quality, and set the stage for a WMO endorsed data exchange standard for water quality (including shared variables).

3.2. Objectives

The objectives of this IE include the following.

  1. Extend and complement existing work of the HDWG, with the goal of advancing the development of WaterML 2.0 suite of standards to the sub domain of water quality observations.

  2. Develop a shared understanding of the dimensions of interoperability required for prominent use cases involving water quality data for both surface and ground waters.

  3. Design and test data interchange mechanisms and vocabularies that achieves the needs of stakeholder organizations and systems.

  4. Complete an ER in the form of either a Best Practice or Standard depending on IE outcomes.

  5. Increase interoperability between in-situ and remote sensing data about water quality.

3.3. Organizational Use Cases

The following initiatives for the basis for the Organizational use cases to be considered in the IE.

  • WMO Hydrologic Observing System Data Sharing Globally

  • US Water Quality Data Exchange & “Internet of Water”

  • Water Quality Data Portal Unified Data Output Format

  • International Water Quality Data Sharing in the EU

  • French national legacy Water Quality system data exposed to research organizations

  • Interoperability between continuous/sensor data and discrete/sample data

The above high-level Organizational use cases will provide overall framing for the IE, but ultimately, the experiment will address specific water quality domain use cases. The specific definition of these domain use cases will be determined as an initial component of the experiment. Potential Water Quality Domain Use Cases include:

  • Surface water chemistry: mainly water samples and chem concentration;

  • Surface water hydrobiology, microbiology: taxa occurrence, indices calculation;

  • Surface water hydromorphology: category observation (shape/type of bank, flow ‘morphology’, etc.);

  • Ground water chemistry: mainly water samples and chemical concentration; and

  • Ground water microbiology: taxa occurrence, indices calculation.

4. Technical Approach

The Technical Approach for this Interoperability Experiment focuses on leveraging existing OGC Standards (see the above mentioned ‘OGC Baseline’) and, as needed, developing Change Requests for those Standards. The following section describes the Technical Approach in detail.

4.1. Experiments

The IE participants will attempt to address the following experiments, which are centered on each of the aforementioned use cases.

  • Experiment A: OGC semantic baseline: Compatibility and utility of existing models/ formats. Is a best practice possible? If not, how much needs to change (extension, profiling) to achieve interoperability?

  • Experiment B: OGC API baseline: Which API (pattern) to serve what? How much change (extension, profiling) is needed to achieve interoperability?

  • Experiment C: Bridging the gap with research activities (e.g., I-ADOPT). Targeting a fine grain description of observable properties and observing procedure.

4.2. Experimental Methodology

Participants in this IE will enlist technology and domain experts from this team as required. Attention will be paid towards encoding and delivery of water quality data and metadata and integration with common WQ taxonomies/ontologies.

Participants will meet at scheduled OGC meetings or other venues, once or twice a year as required, and will otherwise carry out business electronically via email, teleconferencing, and web conferencing.

The IE will kick off with an in-depth analysis of existing use cases and the data exchange arrangements that are currently in use. This harmonization and exploration phase will inform a shared vision of the problem space and what potential solutions may be worth pursuing. Technical experiments will be designed based on the outcomes of this first phase.

Technical experiments will take the form of thought experiments, design workshops, and exploratory model/software development for the sake of evaluation. They will aim to check assumptions and vet approaches such that, at the end of the IE, the activities demonstrate the utility or failings of investigated approaches.

4.3. Demonstration Planning

Demonstrations are planned during OGC Hydro Domain Working Group (DWG) meetings to demonstrate progress. Each demonstration will illustrate more functionality, with the final demonstration showing complete functionality necessary to support the use cases of the IE.

4.4. Standards Development

The primary focus of this IE will be on reusing as much as possible the OGC Standards Baseline. However, if the need arises, the IE will consider the development and testing of evolutions of the Standards (semantics and technical). Such activity will be duly documented in the Engineering Report and reported back to the relevant OGC Standards Working Groups (SWGs) via the appropriate Change Request.

Depending on the result of the experimentation, the IE may also lead to an OGC Best Practice (the form of which is yet to be determined as the pre-existing WaterML-WQ BestPractice will be considered in the IE).

4.5. Component Development

The following components will be developed concurrently by the responsible organization(s), to be completed by the execution end date:

  • A lightweight semantic pattern to exchange Surface water quality data exchange;

  • A lightweight semantic pattern to exchange Ground water quality data exchange;

  • A comprehensive semantic pattern to exchange Surface water quality data exchange;

  • A comprehensive semantic pattern to exchange Ground water quality data exchange;

  • Water Quality data serialization (e.g., OMS JSON);

  • Water Quality data serializations and OGC APIs (OGC API - Features / SensorThings API); and

  • Water quality vocabularies/taxonomies (e.g linked to I-ADOPT)

Other related services/clients that will be possibly covered during the IE:

  • Evolutions of OGC API - Features implementation / evolution of OGC SensorThings API Part 1 implementation; and

  • Desktop clients (e.g., evolution of QGIS GMLAS Toolbox).

4.6. Testing and Integration

Testing and integration will largely involve implementation of the use case(s). At least two testing and integration sessions will be proposed, once at the beginning of the testing and integration period and once directly prior to the demonstration. Others may occur as required. Hydro DWG members will do their best to engage the research community via the RDA Global Water Information Interest Group (GWIIG).

5. Deliverables

The items listed below will be considered the deliverables for the project.

5.1. Documentation

The following documentation will comprise the deliverables for the project:

  • Water Quality IE engineering report:

    • Vetting OGC Baseline for water quality data use cases;

    • Suggesting an update to the WaterML2 Best Practice for Water Quality;

    • Setting the stage for a water quality data exchange standard;

    • Suggesting a common set of water quality variables and practices to semanticize and align them with pre-existing ones; how to express data quality in metadata;

    • The role of COG in OGC standards; and

    • Change Requests, as needed, for OGC Specifications (e.g., Observations, Measurements & Samples JSON encoding, WaterML-WQ, etc.).

5.2. Demonstration

A live virtual demonstration of all functioning components will be made towards the end of the IE.

6. Schedule (Tentative)

Table 1. Master Schedule
Milestone Event Date


OGC Architecture Board approval of Activity Plan

April 2022

Press Release / Call for Participants

July 2022


Planned kickoff date (execution start date)

September 2022

Use Case identification

October 2022

First vocabulary patterns

December 2022

First API Patterns and implementations

March 2023

Iterate on patterns and implementations

March 2023 to June 2023

Change Requests for Standards, revision of Best Practice

June 2023

Wrap-up and Reporting

Technology Demonstration

September 2023

Final ER submission

December 2023

7. Resources

The following resources will be available.

Table 2. Resources
Item Description

Web Resources

OGC will provide a project workspace on the OGC Portal and GitHub or GitLab.


Each initiating and participating organization will provide adequate staff resources to support their defined responsibilities for the duration of the IE.


Initiating organizations will provide hardware as needed to support the IE.


Initiating organizations will provide software as needed to support the IE.

Other Resources

Participants in the IE are self-funded. All expenses incurred in carrying out the IE will be assumed by the participating agencies within their regular line-of-business.

7.1. Requirements for Participation

In order to become a participant in this IE, an organization must be willing make a resource commitment and a substantial contribution in one or more of the following areas:

  • An OGC web service component for water quality data; AND

  • A web client that makes use of service components, OR

  • Testing of the services/clients, OR

  • Provision of observation data, OR

  • Compilation of documentation into one or more of the Interoperability Experiment deliverables (note that all participants must also provide sub-reports for inclusion in the final reports).

7.2. Intellectual property

Intellectual property (IP) brought to the IE will remain with the participants. IP related to advancement of specific agency information systems will also remain with the participants. IP related to the development or advancement of OGC standards (e.g., WaterML 2.0) will rest with the Hydrology DWG and its joint authorities: the OGC and WMO. Any remaining IP that results from the IE will be jointly owned by all participants. The participants agree to respect the collaborative nature of the experiment with due acknowledgement of the participants and, if appropriate, undertake co-authorship in any ensuing materials.