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Primary Flood Defenses — Rijkswaterstaat / Netherlands

What This Dataset Is

238 LineString features representing primary flood defense sections (primaire waterkeringen) in the Netherlands — the dike sections that protect the country from flooding from the sea, major rivers, and large lakes. These are regulated under the Water Act (Waterwet) and subject to periodic safety assessments.

The Netherlands has one of the world's most sophisticated flood defense systems. These primary defenses protect roughly 60% of the country that lies below sea level or is flood-prone. Each section (traject) has legally prescribed safety norms that specify the maximum acceptable probability of failure or flooding.

Provider: Rijkswaterstaat (Directorate-General for Public Works and Water Management) License: Public domain (Dutch government open data)

How to Access

The data is a GeoParquet file in EPSG:28992 (Amersfoort / RD New). Use DuckDB with the spatial extension.

Schema — Field Meanings

Field	Type	Meaning
`geometry`	WKB LineString	Defense section geometry in EPSG:28992.
`TRAJECT_ID`	string	Section identifier (e.g., `"1-1"`, `"13-5"`). The primary key for each dike section.
`NORMTYP_O`	string	Norm type: `"Faalkans"` (failure probability) or `"Overstromingskans"` (flooding probability).
`NORM_SW`	float64	Safety norm value — signaling level (signaleringswaarde).
`NORM_OG`	float64	Safety norm value — lower limit (ondergrens).
`NORM_THB`	float64	Safety norm value — currently applicable norm.
`NORM_NS`	float64	Safety norm value — new norm (nieuwe signalering). Higher values = stricter norms.
`WET_JN`	string

Useful Query Patterns

Total length of flood defenses

Group by norm type

Find sections with strictest norms

Legally established vs not

List all sections sorted by length

Geometry Notes

CRS is EPSG:28992 (Amersfoort / RD New). Coordinates are in metres.
All geometries are LineString — representing the line of the flood defense.
Reproject to EPSG:4326 for web maps.
Shape__Length gives the section length in metres.

Visualization Styles

One Mapbox GL v8 style is available for interactive map visualization via the PMTiles file.

Style files are Mapbox GL v8 JSON with relative PMTiles source paths. They can be used with MapLibre GL JS, OpenLayers (via ol-mapbox-style), or any Mapbox GL v8-compatible renderer.

styles/default.json — Bold red lines showing primary flood defense routes, with width increasing at higher zoom levels. Shows the critical Dutch dike and flood defense infrastructure.

Style files are at: https://data.source.coop/cholmes/portolan-nl/rijkswaterstaat/waterkeringen/styles/

Caveats

Norm values are probabilities — higher numbers mean stricter requirements. NORM_SW through NORM_NS represent different assessment thresholds, not independent norms.
NORMTYP_O distinguishes between two norm frameworks: "Faalkans" (probability of structural failure) and "Overstromingskans" (probability of actual flooding).
Column names use uppercase and Dutch abbreviations (e.g., NORMTYP_O, WET_JN).
Shape__Length uses double underscores (ArcGIS convention).
Validity periods (FL_BEGIN, FL_EINDE, etc.) may contain various date formats.

Hand-maintained agent guide (ported from this collection's llms.txt in August 2026). Update it alongside collection.json.