Sharing Water Information in France via Standards

François-Xavier Prunayre
GIS Engineer
International Office For Water

The French Data Reference Centre for Water (Sandre) has been in charge of implementing a common language for water data exchange since 1993. The Sandre is a common initiative within the French Information System for Water (SIE), a national project managed by the French Ministry of Ecology and sustainable development. The French Information System for Water includes ministries, river basin agencies, offices for water, INERIS (National Institute for the Industrial Environment and Risk), BRGM (Bureau of Research for Geology and Minerals), EDF (electric group), MeteoFrance (weather agency) and the Office International de l'Eau (International Office of Water).

Geospatial information is exchanged on a regular basis (in real time and periodically, such as annually) between different partners. The information covers all aspects of water (waste water, Water Framework Directive, hydrography, surface water, ground water, marine water…). Since its creation, the Sandre has been in charge of disseminating core water datasets in France. The first approach was to define a common language (models, exchange formats and data flows) to apply to tabular data dealing with simple geometries (points). With Open Geospatial Consortium (OGC) standards, geographic data exchange has been greatly improved.

As OGC specifications have matured, the Sandre took two big steps. It:
- Published all core datasets using the OpenGIS® Web Map Service (WMS) and OpenGIS® Web Feature Service (WFS) specifications in 2005
- Moved from a "manual" data collection process to a distributed architecture for publication of core datasets in 2006.

The distributed architecture was originally based on three main nodes. In September 2006, the number increased to five.

In 2005, the Sandre defined rules for a common architecture based on Web services. The 69 rules define interfaces needed to be able to communicate between partners. During the definition of the rules, a prototype using the three main languages (Java, .Net, PHP) was tested using World Wide Web Consortium (W3C) and OGC standards. Tests were done on data types, protocols (REST/SOAP), tabular and geographic data.

The first online application deployed using those ruleS was the Web mapping portal of the Sandre. The interface allows the public to have free access to more than 60 layers related to water in France including rivers, aquifers, monitoring stations, protected areas, main water infrastructure and more. This apphication was implemented by the International Office for Water in cooperation with CampToCamp, DMSolutions and IFReMER (French Research Institute for Exploitation of the Sea).

The Sandre has provided public Internet access since 1997. This is the public interface for the Sandre portal.

Other nodes can be set up on any other platform supporting WMS for visualisation and WFS for asynchronous data export. The first two partners to be connected to the portal were the IFREMER, which published monitoring stations for marine water (using Mapservar, Oracle and Java) and the Ministry of Ecology (IREP), which published structures that discharge pollutants in water (using Mapserver, PostGIS, PHP).

The portal also provides access to metadata through a GeoNetwork node. The metadata catalogue is used to store metadata in the ISO 19115 format for geographic, non-geographic data and services. The metadata catalogue is used by the Web mapping application to search for available WMS layers and populate a list of WMS services for the end-user.

The Sandre decided to create its own Web services specification to get metadata on the features, that is, to provide a description of geometric features. This service has been defined to work with the ISO19139 standard.

Metadata from the Sandre portal.

The Gazetteer uses the GeoNames Web service to allow users to locate any point of interest (administrative units, roads, streams, mountains, seas…) France and overseas territories in a consistent manner.

The software products behind the Web mapping portal are Mapserver and Cartoweb. The latest AJAX implementation of Cartoweb improved the usability of the interface significantly.

In the future, the Sandre hopes to have a more distributed platform to access more up to date datasets from more sources. In a wider context, the Sandre data has to be disseminated to the public following the rules defined by INSPIRE (The INfrastructure for SPatial InfoRmation in Europe) and WISE (Water Information System for Europe). For now, the core datasets are freely accessible through the Web and visitors are able to work with attributes data on different themes.

During the implementation, the Sandre team identified and managed several risks:
- error handling between nodes (timeout, network error) and the provision of an error alert to the user
- standardized style description for water features using the OpenGIS Styled Layer Descriptor (SLD) specification
- increased performance