New steps toward sharing hydrological data

A 2005 report from the Global Climate Observing System (GCOS) on data exchange problems in global hydrological and atmospheric networks identified standards as a key challenge. It stated that: “There are no established international standards on the acquisition of river data, the set of required metadata, data formats, and transmission modes.” â©

In 2009, the World Meteorological Organization (WMO) and the OGC jointly formed a hydrology domain working group, Hydrology DWG, to address this problem. In June this year, the Geological Survey of Canada’s Quebec Office and the Institut National de la Recherche Scientifique in Quebec City, Canada, hosted the fourth workshop of the Hydrology DWG. This was the 21st meeting of the group and their fourth four-day workshop. It was also their first workshop since the completion and adoption last year of the ground-breaking OGC WaterML 2.0 Encoding Standard.â©
OGC WaterML 2.0â©

WaterML 2.0 is a standard information model for the representation of water observations data, developed for the exchange of such datasets across information systems. Through the use of XML and existing OGC standards, WaterML 2.0 provides an interoperable exchange format that may be used to address a wide range of exchange requirements. It supports traditional data co-ordination efforts and also provides a new facility for automated integration of datasets and data streams that use different data models. â©

Paul Sheahan from the Australian Bureau of Meteorology and Peter Taylor of CSIRO discussed the recent call for public comment on the OGC’s WaterML 2.0 ratings, gaugings and sections discussion paper. This document describes an information model for exchanging rating tables, or rating curves, that are used for the conversion of related hydrological phenomena. The specification also describes a model for the observations that are used to develop such relationships, often referred to as ‘gaugings’ or gauging observations.â©

The WMO reportâ©

Tony Boston and Uli Looser described the challenges facing the WMO Commission for Hydrology (CHy), and reported on the CHy’s 2013-2016 data operations and management work plan. The commission is tasked with monitoring and reporting on new developments dealing with hydrologic data management issues. It also supports and promotes the free and open exchange of hydrological data (and products) and provision using web-based services. â©

A CHy resolution urges WaterML 2.0 pilot projects in WMO member countries. The commission recently noted the importance of WaterML 2.0 and other emerging OGC standards in improving service delivery of key CHy programmes, including the WMO’s World Hydrological Cycle Observing System (WHYCOS) and the WMO Flood Forecasting Initiative.â©
RiverML – a proposed standardâ©

Stephen Jackson, David Arctur and David Maidment from the Center for Research in Water Resources at the University of Texas at Austin presented the draft River Markup Language (RiverML), a language for exchange of river geometry and flow information. RiverML is intended to simplify analysis workflows, reducing the number of conversions between different software systems and reducing the possibilities for error. It is based on the HEC-GeoRAS format developed by the US Army Corps of Engineers.â©

RiverML will also provide a basis for innovation in analysis and rapid reporting of river events. Based on the similarities between river networks and microprocessor design, it provides fully dynamic solutions to St Venant equations for very large networks of river branches. The new standard would also make it easier to link GIS and other analysis tools with modelling software inputs and outputs.â©

A number of participants volunteered to participate in the drafting of an OGC standards working group charter to create a group to finish the RiverML work that has begun, potentially leading to its adoption as an OGC standard.â©

GEOSS Water Servicesâ©

David Arctur spoke about the status of the water services activity in the Global Earth Observation System of Systems (GEOSS), a multi-year project of the international Group on Earth Observations. In the architecture implementation pilot phase 6 GEOSS Water Services activity, participants work to provide additional operational, federated water information resources in GEOSS. This is a large project with participation from agencies, vendors and academia from North America, Europe, New Zealand, Japan and Latin America. Its focus is the development of a global registry of water data, map and modelling services catalogued using the standards and procedures of the OGC and the WMO. â©

OGC testbeds and interoperability experimentsâ©

Sponsors and participants of two OGC interoperability initiatives – the groundwater interoperability experiment, phase two (GWIE2) and the climate-hydrologic information sharing pilot, phase one (CHISP-1) – reported on the status of these projects.â©

Boyan Brodaric of the Geological Survey of Canada, Natural Resources Canada, reported on GWIE2. Now in its second phase, the GWIE was designed to: â©

• Test the use of both WaterML 2.0 and Groundwater ML with the OGC Sensor Observations Service (SOS) and Web Feature Service (WFS) interface standards, respectively.â©
• Test compatibility with industry software clients.â©
• To facilitate the sharing of massive volumes of sensor-based water-level observations and related water-well features across the Canadian-US border.â©

The GWIE team concluded that delivery of groundwater feature data using WFS and Groundwater ML, and delivery of groundwater observation data using SOS and WaterML 2.0, was adequate for schematic interoperability across the US-Canadian border, but only after best practices were developed for the deployment of these standards and related technologies. â© It also concluded that deployment of the standards, specifications, and best practices by clients allowed for reasonable viewing and downloading of feature and observation data. However, querying groundwater observations as time series is still a challenging task requiring further development of standards.â©

Lastly, Peter Vretanos of CubeWerx and Lewis Leinenweber of the OGC presented the results of the recently completed climate-hydrologic information-sharing pilot, phase one (CHISP-1). The primary goal of CHISP-1 was to develop and test an open architecture for reporting flooding and nutrient loading, one that is thoroughly grounded in international geospatial standards. A secondary goal involves reducing the cost, effort, and complexity associated with shared spatial data management and delivery to stakeholders. â©

Initial testing demonstrates achievement of the primary goal – the resultant architecture leverages standards for both data access and data structure: for example, the SOS standard for accessing sensor measurements and WaterML 2.0 for structuring water time-series, among others. Satisfaction of the secondary goal is under evaluation as a longer-term prospect. â©

There are no established international standards on the acquisition of river data, the set of required metadata, data formats, and transmission modesâ©

Ulrich Looser is head of the Global Runoff Data Center, Federal Institute of Hydrology (www.bafg.de/GRDC)â©

Tony Boston is branch head of climate and water data at the Australian Bureau of Meteorology (www.bom.gov.au)â©

Ilya Zaslavsky is director of the Spatial Information Systems Laboratory, San Diego Supercomputer Center, University of San Diego (www.sdsc.edu)