Add governed bathymetry profile workflow

2026-07-17 15:25:00 +02:00
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+# Bathymetry expansion roadmap
+
+## Purpose
+
+GeoIntel must distinguish three different questions:
+
+1. Where were cross-sections measured and what does the source document say?
+2. What is the continuous elevation of the bed at a specific survey epoch?
+3. What is the water depth or volume at a specific moment?
+
+Only the first question is operational for Mol through the VHA cross-section
+profile layer. A bed model does not provide water depth without a compatible
+water-surface elevation. Flood-hazard maximum depth is a scenario result and
+must not be reused as current water level.
+
+## Governed source matrix
+
+| Source | Coverage | Data | Vertical reference | GeoIntel status |
+| --- | --- | --- | --- | --- |
+| VMM VHA Digital Atlas | Flanders | Point locations, structured profile fields, PDF evidence | Document-specific | Operational, bounded vector acquisition |
+| MDK Belgian Continental Shelf model | Belgian North Sea | Continuous 20 x 20 m bathymetric raster | LAT | Available, not integrated |
+| SPW navigable waterways and reservoir lakes | Wallonia | 0.5 m bed-elevation raster and XYZ cloud | mDNG | Available, not integrated |
+| Port of Antwerp-Bruges publications | Port survey areas | Periodic soundings | Product-specific | Catalog candidate |
+
+VHA contains approximately 129,643 profile points across Flanders at the
+observed catalog state. This is a scale indication, not a fixed contractual
+count. Mol contained 828 exact in-boundary points during source validation,
+715 with document links and 112 with a structured depth field. Production
+provisioning always records the live counts and checksums.
+
+## Operational tier 1: Mol
+
+- Query only an explicit EPSG:4326 bbox.
+- Intersect the bbox with the exact persisted Mol Area.
+- Page the official ArcGIS FeatureServer response without truncation.
+- Resolve VHA watercourse names from the official atlas layer.
+- Normalize profile points to EPSG:4326.
+- Persist the artifact through `DatasetService.import_vector_bytes`.
+- Persist every point through `VectorFeatureService`; the provider never
+  writes directly to `vector_features`.
+- Expose document, measurement date, depth and width fields without parsing or
+  inventing values from scanned PDFs.
+- Keep volume unsupported.
+
+## Tier 2: all of Flanders
+
+Flanders must be provisioned as exact municipality or other approved Area
+partitions, not as one monolithic request. The backend feature limit protects
+the provider and the application. A regional logical layer may group complete
+partitions, but each Dataset retains its Area id, query URLs, checksums, exact
+count and measurement-date range.
+
+Before regional activation:
+
+- add a governed Flanders boundary manifest and partition coordinator;
+- prove idempotent resume and no duplicate VHA `OBJECTID` within a partition;
+- benchmark PostGIS point selection and viewport delivery;
+- add freshness/version probing for the VHA MapServer;
+- keep individual profile dates instead of fabricating one Dataset
+  `observed_at`.
+
+## Tier 3: Belgium
+
+Belgian coverage is a federation of source adapters with one normalized
+contract, not one assumed national dataset:
+
+- Flanders: VHA profiles and future validated bed rasters;
+- Wallonia: SPW bathymetry for measured navigable waterways/reservoirs;
+- Brussels: hydrological context until an authoritative public bathymetric
+  product is identified;
+- federal/maritime: MDK and legally appropriate maritime boundaries.
+
+Every adapter must emit:
+
+- authority and owner;
+- exact geographic and temporal coverage;
+- horizontal and vertical CRS/datum;
+- survey/acquisition time;
+- resolution or sample density;
+- source URL, request identity, checksum, attribution and license;
+- explicit supported and unsupported metrics.
+
+LAT, TAW and mDNG values must never be merged or compared without a documented,
+tested vertical transformation and uncertainty statement.
+
+## Tier 4: the Belgian North Sea
+
+The map must distinguish:
+
+- the Belgian land boundary and baseline;
+- the territoriale zee (up to 12 nautical miles);
+- the Belgian EEZ and continental shelf, which are jurisdictional maritime
+  zones and should not be labelled ordinary municipal or provincial
+  "grondgebied".
+
+The MDK bathymetry WCS is the preferred continuous source candidate. Activation
+requires a live Docker validation of TLS/certificates, GetCapabilities,
+coverage identifiers, bounded GeoTIFF retrieval, CRS, LAT, nodata, pixel size,
+response limits and maritime clipping. WMTS can support visual context but is
+not the analytical source.
+
+## Depth and volume rules
+
+For a compatible bed raster and water-surface raster at the same time and
+vertical datum:
+
+`volume_m3 = sum(max(0, water_surface_z - bed_z) * cell_area_m2)`
+
+For surveyed cross-sections along a connected reach:
+
+`volume_m3 = sum(((section_area_i + section_area_i+1) / 2) * reach_length_i)`
+
+The second method requires complete profile geometry, ordered chainage,
+contemporaneous water level and defensible interpolation. VHA profile points
+alone do not satisfy those prerequisites.
+
+Historical evolution compares only survey epochs with documented compatible
+coverage, datum and method. A changed raster footprint is not automatically
+bed evolution.
+
+## Implementation order
+
+1. Operate and validate the Mol VHA profile Dataset and map flow.
+2. Add VHA municipal partition orchestration for Flanders.
+3. Implement a bounded MDK WCS probe, then acquisition behind live evidence.
+4. Implement SPW download staging and vertical-datum metadata validation.
+5. Add maritime boundaries as separate authoritative scope layers.
+6. Add cross-source vertical-datum transformation only with authoritative
+   grids/parameters and uncertainty tests.
+7. Add volume only after a compatible measured or modeled water-surface source
+   is part of the same analysis contract.