10 successful years of the Hydrology Domain Working Group

Contributed by: 
Tony Boston, co-chair of the Hydrology Domain Working Group


The 2008 edition of Volume 1 of the World Meteorological Organisation (WMO) Commission for Hydrology (CHy) Guide to Hydrological Practices stated that “There are currently no standards for data exchange formats for hydrological data”. The work of the OGC/WMO Hydrology Domain Working Group (HDWG) since then has helped remedy this situation with the development of WaterML2 standards (described in more detail below), and their uptake by organisations from around the world. In May 2017, the WMO Executive Council formally adopted WaterML2: Parts 1 and 2 as official standards for use by National Hydrological Services and within the WMO Hydrological Observing System (WHOS). Future WMO adoption of the WaterML2: Parts 3 and 4 standards is expected. Using WaterML2 and OGC’s interoperability standards, the linking of local, national, regional and global water information systems is now possible, providing quality hydrological data that can be used in decision-making for all aspects of water resources management.

In September 2018, the HDWG held its ninth workshop, marking ten years of successful collaboration between WMO and OGC in hydrology and informatics. The working group develops technical solutions and standards for exchanging data describing the state and location of water resources, both above and below the ground surface. The HDWG includes representatives of member organisations of the OGC drawn from government agencies, industry, universities, and non-government organisations largely from Europe, North America, and Australasia.

HDWG workshops, held annually since 2010, aim to progress the development of standards and best practices for water data. The working group has generated interoperability experiments, engineering reports, discussion papers, best practice documents, and four approved OGC standards. These standards make up part of the WaterML2 suite: Part 1 (Timeseries) defines an information model and encoding for timeseries observations enabling exchange of hydrological data, such as water level or discharge, between information systems; Part 2 (Ratings, Gaugings and Sections) deals with rating conversions (stage to discharge etc), gauging observations and river cross-sections which are part of most surface water monitoring programs; Part 3 (Surface Hydrology Features) is a conceptual model describing surface water hydrologic features such as rivers, lakes, catchments and drainage networks; and Part 4 (GroundWater Markup Language 2 [GWML2]) supports the description of key hydrogeological entities such as aquifers and water wells, as well as related measurements and groundwater flows. Further standards dealing with water quality, river network topology, channel geometry etc will require champions from the hydrology and technology communities to get involved to extend the WaterML2 suite.

The most recent workshop was held, appropriately, in Geneva at WMO headquarters hosted by WMO Climate and Water Department and the Commission for Hydrology (CHy). The overall goal of the meeting was to strengthen connections between OGC and WMO and activities of the working group and CHy, including definition of HDWG strategies and objectives for the next ten years. About 25 people from ten countries participated in the workshop. Topics covered included: WMO information systems; examples of surface, groundwater, and environmental data sharing using OGC standards; linked data initiatives; HDWG collaboration with the Research Data Alliance; WMO-OGC cooperation and future directions focussing on increasing the adoption of hydrological data standards.

Meetings, presentations and working documents of the HDWG are publicly accessible and new members are always welcome. For more information, including how you can contribute to the Working Group, visit the OGC/WMO Hydrology Domain Working Group (HDWG) page on the OGC Website.

Special presentation: The Hydrology DWG through the ages:

Attendees of the 2nd OGC/WMO Hydrology DWG Workshop - UNESCO-IHE, Delft, the Netherlands
Attendees of the 2nd OGC/WMO Hydrology DWG Workshop, 2011 - UNESCO-IHE, Delft, the Netherlands.


Attendees of the 3rd OGC/WMO Hydrology DWG Workshop, 2012 - University of Reading, Reading, UK.
Attendees of the 3rd OGC/WMO Hydrology DWG Workshop, 2012 - University of Reading, Reading, UK.


Attendees of the 4th OGC/WMO Hydrology DWG Workshop - Institut National de la Recherche Scientifique, Quebec City, Canada
Attendees of the 4th OGC/WMO Hydrology DWG Workshop, 2013 - Institut National de la Recherche Scientifique, Quebec City, Canada.


Attendees of the 5th OGC/WMO Hydrology DWG Workshop – City College of New York, USA
Attendees of the 5th OGC/WMO Hydrology DWG Workshop, 2014 – City College of New York, USA.


Attendees of the 6th OGC/WMO Hydrology DWG Workshop – BRGM, Orléans, France
Attendees of the 6th OGC/WMO Hydrology DWG Workshop, 2015 – BRGM, Orléans, France.


The final day of the 9th OGC/WMO Hydrology DWG Workshop, 2018, involved a technical visit to UNECE
The final day of the 9th OGC/WMO Hydrology DWG Workshop, 2018, involved a technical visit to UNECE.