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Data Access and Exchange

At its fourteenth session in 2012, the Commission for Hydrology (CHy-14) examined the issue of data access and exchange, particularly the need for standards to improve the interoperability of data and information systems.

This examination took place following a concern stated in the 2008 edition of the WMO Guide to Hydrological Practices that

“There are currently no standards for data exchange formats for hydrological data”. 

The Commission noted that the World Meteorological Organization (WMO) had signed a Memorandum of Understanding with the Open Geospatial Consortium (OGC) in 2009 to enhance the development and use of geospatial standards.  Moreover, in conjunction with the Memorandum, WMO and OGC had jointly formed a Hydrology Domain Working Group (HDWG) specifically to address the issue of hydrological data exchange formats.

Through the activities of the HDWG, WaterML 2.0 was adopted by the OGC as an official standard in 2012. WaterML 2.0 is a standard information model for the representation of water observations data, developed to enable the exchange of hydrological data between information systems. It provides an interoperable hydrological exchange format that may be used to address a wide range of user needs. These include the exchange of data relating to:

  1. In situ observations at hydrological (gauges, reservoirs) or climatological stations;
  2. Forecast products (probabilistic or deterministic time series) at forecast locations;
  3. Emergency or operator-oriented alerts (of threshold exceedance) and reports;
  4. Time series of planned intake and release/discharge; and
  5. Groundwater observations of water level within wells.

Using WaterML 2.0, the linking of local, national, regional and global water information sources is possible as part of global water information networks.

In response to this development, the Commission for Hydrology adopted Resolution 3 at CHy-14 recommending that WMO Members test, through pilot projects during 2013-16, the use of WaterML 2.0 for the exchange of hydrological data, with a view to possibly adopting WaterML 2.0 as a joint WMO/ISO standard. The Commission also noted the importance of WaterML 2.0 and other emerging OGC standards to improve service delivery of key CHy programmes including the WMO's World Hydrological Cycle Observing System (WHYCOS) and the WMO Flood Forecasting Initiative.

Through the CHy Data Operations and Management thematic activity, the Commission has undertaken several pilot projects that demonstrate the use of WaterML 2.0 for exchange of hydrological data at global, national or state/provincial levels.  The results of these demonstrations will be reported at CHy-15 in November 2016, along with a recommendation as to whether CHy should support the adoption of WaterML 2.0 as a joint WMO/ISO standard.

In conjunction with this effort, and in response to the need for CHy to more closely align its data activities with the WMO Integrated Global Observing System (WIGOS) and the WMO Information System (WIS), the CHy Advisory Working Group has endorsed the development of a WMO Hydrological Observing System (WHOS) as the hydrological component of WIGOS. 

It is proposed that WHOS be designed to provide access to the data holdings of those National Hydrological Services (NHSs) that make their data freely available online.  It is being developed in stages.  The first stage is the establishment of a simple map-based interface to the websites of NHSs that currently serve their data online.  The second stage would be a more sophisticated implementation of data access and exchange that will employ an interoperable portal through which the data services of National Hydrological Services can be accessed.  Initially, there will likely be a limited number of NHSs that will be accessible through this interoperable portal.  Through time, however, services and training will become increasingly available to build data exchange capabilities in NHSs wishing to make use of them.  The stage one map interface will be operating in mid-2015, and a demonstration version of the second stage will be presented at CHy-15 in late 2016.  If approved by CHy-15, an operational version of the second stage WHOS portal will be implemented during the intersessional period following CHy-15.

To learn more about the various aspects of data access and exchange see the report entitled WMO Data Operations and Management: Global initiatives in hydrological data sharing.



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