Add governed DHMV terrain analysis

docs/DATA_SOURCES.md

@@ -220,9 +220,10 @@ until a governed operator import, provenance record and validation pass exist.
 - Buildings and Addresses Register (Digitaal Vlaanderen): continuously updated
   building status, life cycle and address linkage; complementary to GRB
   geometry and not yet imported.
-- DHMV II DTM/DSM (Digitaal Vlaanderen): 1 m/5 m elevation based on 2013-2015
-  LiDAR, suitable for elevation, slope and drainage. It does not provide water
-  depth.
+- DHMV II DTM/DSM (Digitaal Vlaanderen): governed bounded WCS acquisition is
+  implemented below. The official 1 m source and 5 m analysis copy are suitable
+  for measured elevation, relief and slope. Drainage remains an interpretation;
+  the products do not provide water depth.
 
 ## Governed BWK and Natura 2000 state 2025
 
@@ -322,10 +323,22 @@ quality metrics.
 
 - Naam: Digitaal Hoogtemodel Vlaanderen
 - Type: raster/hoogte
-- Gebruik: DEM, DSM, helling, laagste punten
-- Toegang: Vlaamse open data, download/WCS nader te bepalen
-- Cache: raster storage
-- Prioriteit: V3
+- Gebruik: DTM/DSM hoogte, reliëf, helling en laagste punten
+- Toegang: productie-WCS `https://geo.api.vlaanderen.be/DHMV/wcs`
+- Coverages: `DHMVII_DTM_1m`, `DHMVII_DSM_1m`
+- Native raster: 1 m Float32, EPSG:31370, nodata `-9999`, hoogte in TAW
+- Opnameperiode: 2013-2015; geen uniforme recente peildatum
+- Cache: canonical raster Dataset plus WCS request/response/output checksums
+- Operator: `scripts/provision_mol_dhmv.py`
+- Prioriteit: P4 uitgevoerd voor Mol
+
+The operator requests a bounded 5 m analysis copy by default so a complete
+municipality remains operationally manageable while retaining the official
+1 m native resolution in source metadata. The response is clipped to the exact
+persisted Area before `DatasetService` stores it. DTM is bare-earth terrain;
+DSM includes buildings and vegetation. Neither is exposed as water depth,
+water volume or a directly measured building-height product. A drainage model
+would require a separately governed hydrological processing pass.
 
 ## Gebouwenregister