Agent Guidance, Netherlands Provinces

Dutch province polygons whose identificatie codes PV20 to PV31 join CBS StatLine, the same code system all Dutch government data uses at province level. The code column, bare 20 to 31, joins the municipality layer of the same upstream GeoPackage on ligt_in_provincie_code.

Query the GeoParquet data asset in place with DuckDB spatial, read_parquet('netherlands-provinces.parquet'), or load it with GeoPandas. It streams over HTTP range requests, so query the published URL directly rather than downloading first. For rendering use the visual PMTiles asset with its MapLibre styles.

Coordinate Reference System

EPSG:28992, Amersfoort / RD New, a projected coordinate reference system whose coordinates are in metres. Planar distance and area functions return metres and square metres directly, so no geodesic correction is needed. Web maps and anything joined to data in degrees need a transform to EPSG:4326 first. The data asset carries the same code as proj:code.

This is the Dutch national grid, valid only for the European Netherlands. Divide ST_Area(geom) by 1e6 for square kilometres and the results match CBS official figures to one decimal. The transform web maps need is ST_Transform(geom, 'EPSG:28992', 'EPSG:4326', always_xy := true), and without always_xy the axes come back flipped. Points must be transformed into RD before ST_Contains. The bbox covering column is also in RD meters, while the STAC extent in collection.json is WGS84.

Quirks

• Fryslân, not Friesland. The naam column uses official spellings with diacritics.
• Noord-Brabant is a 9-part multipolygon with 22 holes, the Baarle enclave complex on the Belgian border. Belgian exclaves are punched out and 8 tiny Dutch counter-enclaves float inside them, so one-province-one-polygon assumptions and small-area filters both break.
• Provinces include their water. Fryslân is the largest by total area and third by land.
• CBS OData v3 keys carry trailing spaces, PV20 with two spaces. Trim before joining.
• fid order is arbitrary, Flevoland is 1 and Groningen is 11. Key on code or identificatie.

Tested Queries

Areas that reproduce official statistics.

Which province contains a point, in RD meters. Amsterdam.

The Baarle enclave forensic, parts of Noord-Brabant.

Related Collections

The upstream GeoPackage also carries the 342 municipalities (gemeentegebied) and the national outline (landgebied), joined on the code columns above. Within this catalog the other boundary Collections connect only spatially. Converted from PDOK's GeoPackage with DuckDB spatial into web-optimized GeoParquet 2.0, preserving the source CRS. The mirrored ISO 19115 record is the metadata asset beside the data.