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In 2014, the National Geographic Institute of Spain (IGN) launched a new production system of Geospatial Reference Information (GRI) of high resolution and INSPIRE compliant (2007/2/CE Directive), in line with the United Nation decisions about GRI Management and also fitting user requirements at national, European and global level.
In the case of IGR of hydrography, there is a need of providing information for mapping and for hydrological simulation including the topological network and also digital hydrological models, as flow direction and accumulation models.
The application schema generated at IGN Spain is INSPIRE compliant and is based in the two use cases developed in the INSPIRE specifications:
Physical Waters: for mapping purposes. It includes the representation of rivers, channels, man-made objects, basins and hydrographic points of interest. The schema has been extended to meet national requirements, adding new attributes and defining codelists for some free text data types. The translation of the existing data into de INSPIRE conformant model did not carry any difficulty, apart from some editions to change some geometry types.
Network model: for spatial analysis and modelling. It includes the topological network of rivers and channels. The Spanish GRI_HY network model is identical to the one defined in INSPIRE data specifications. In this case, the difficulty consisted on creating the fictitious axis that did not exist previously.
The production of GRI of hydrography following GRI_HY Data specifications was carried out at two levels: considering the existing data (GRI_HY v.0) and from a new geometry (GRI_HY v.1):
GRI_HI v.0: The National Topographic Database at 25k scale consists on more than 4,200 sheets covering the whole Spain with complete information for GIS analysis, obtained from photogrammetric restitution techniques. In order to produce GRI_HY data from existing hydrography at BTN25, it was necessary some editions, a data model conversion and a conflation with a national hydrography network database for Pfatstetter code assignation. Nowadays, the database is fully loaded and a WFS for feature download has been successfully developed: http://www.ign.es/wfs-inspire/hidrografia.
GRI_HI v.1: A new methodology was developed for automatic stream network extraction from a DTM obtained from LiDAR data through flow accumulation calculations. The automatic phase for network extraction took 8 months of processing and 40 servers working. The edition and conflation, was outsourced and finished in 2016, and now the quality control is taking place. The final data will be ready by the end of 2017.
Topic Area: [3.1] Fostering “Fitness for purpose” Abstract Type: Oral Presentation
Comments: Hydrography, Geospatial Reference Information, GRI, INSPIRE implementation
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