{
  "generated_at_utc": "2026-09-24T18:52:49.194845+00:00",
  "crs": "OGC:CRS84 (WGS84 longitude, latitude; RFC 7946 GeoJSON)",
  "scope": {
    "center_latitude": 51.5074,
    "center_longitude": -0.1278,
    "radius_km": 50,
    "note": "Circle is the initial operational area. London boroughs remain whole. Connected upstream catchments are a future separate scope, not inferred from this circle."
  },
  "layers": {
    "boroughs": {
      "file": "london-boroughs.geojson",
      "feature_count": 33,
      "title": "ONS Local Authority Districts (December 2025), UK BGC — London subset",
      "vintage": "2025-12",
      "generalisation_m": 20,
      "source_url": "https://services1.arcgis.com/ESMARspQHYMw9BZ9/arcgis/rest/services/Local_Authority_Districts_DEC_2025_Boundaries_UK_BGC/FeatureServer/0",
      "query_url": "https://services1.arcgis.com/ESMARspQHYMw9BZ9/arcgis/rest/services/Local_Authority_Districts_DEC_2025_Boundaries_UK_BGC/FeatureServer/0/query?where=LAD25CD+LIKE+%27E09%25%27&outFields=LAD25CD%2CLAD25NM&returnGeometry=true&outSR=4326&f=geojson",
      "publisher": "Office for National Statistics",
      "licence": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
      "licence_source_url": "https://www.ons.gov.uk/methodology/geography/licences",
      "attribution": "Source: Office for National Statistics licensed under the Open Government Licence v.3.0. Contains OS data © Crown copyright and database right 2025.",
      "refresh": "Check ONS releases annually; preserve boundary vintage for statistical joins.",
      "limits": "20 m generalised display boundaries; not parcel-level adjudication."
    },
    "study_area": {
      "file": "london-area.geojson",
      "feature_count": 1,
      "title": "London 50 km initial operational area",
      "generated_geometry": true,
      "method": "720-segment inscribed circle, spherical azimuthal equidistant projection, mean Earth radius 6371008.8 m, matching collector great-circle distance convention.",
      "maximum_circle_chord_inset_m": 0.476,
      "limits": "A collection/display boundary, not a catchment or administrative boundary."
    },
    "rivers": {
      "file": "rivers.geojson",
      "feature_count": 4863,
      "distinct_nonempty_primary_names": 571,
      "bbox_candidates": 6545,
      "title": "OS Open Rivers — watercourse links clipped to London 50 km area",
      "vintage": "2026-04",
      "source_url": "https://api.os.uk/downloads/v1/products/OpenRivers",
      "download_catalogue_url": "https://api.os.uk/downloads/v1/products/OpenRivers/downloads?area=GB&format=GeoPackage",
      "source_file": "oprvrs_gpkg_gb.zip",
      "source_zip_bytes": 52490978,
      "source_zip_md5": "4b62effb1c7980f3320d400b76b4f4b0",
      "source_zip_sha256": "b31e85f9fd412a48f61012c3945e9a60e284cab9f9fb7c49fa54c3cfc6c7053e",
      "publisher": "Ordnance Survey",
      "licence": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
      "attribution": "Contains OS data © Crown copyright and database right 2026.",
      "refresh": "April and October releases; rerun extraction when the product version changes.",
      "source_crs": "EPSG:27700",
      "processing": "Transform to WGS84, clip and simplify in a spherical local azimuthal equidistant projection, export longitude/latitude.",
      "display_simplification_m": 2,
      "coordinate_decimals": 7,
      "bng_to_wgs84_operation": "Inverse of British National Grid + OSGB36 to WGS 84 (6) (with axis order normalized for visualization)",
      "bng_to_wgs84_accuracy_m": 2.0,
      "limits": "Generalised high-level watercourse network; no river width, complete small-stream coverage, sewer model or lost-river guarantee. Clipped geometry is for display: source node IDs/lengths refer to the original links, and must not be used as an unmodified routing graph."
    }
  },
  "basemap_options": [
    {
      "name": "OS Open Zoomstack",
      "source_url": "https://www.ordnancesurvey.co.uk/products/os-open-zoomstack",
      "licence": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
      "refresh": "June and December",
      "note": "Optional openly licensed background. Build a local tile extract once; do not send the national MBTiles/GeoPackage file to the browser."
    },
    {
      "name": "OpenStreetMap Standard",
      "tile_url": "https://tile.openstreetmap.org/{z}/{x}/{y}.png",
      "attribution": "© OpenStreetMap contributors",
      "licence_url": "https://www.openstreetmap.org/copyright",
      "usage_policy_url": "https://operations.osmfoundation.org/policies/tiles/",
      "note": "Optional interactive-view tiles only, with visible attribution, normal cache/referrer behavior and no bulk/offline prefetch. Service has no availability guarantee; URL should be configurable."
    }
  ],
  "outputs": {
    "london-boroughs.geojson": {
      "bytes": 162957,
      "sha256": "0fd77a85b27b3c68eb57da68b211bf20a462fce2118ac6933bb4cfb6f52e1b67"
    },
    "london-area.geojson": {
      "bytes": 17249,
      "sha256": "a0b8a37ebdd65cbd444f93b7fa432ba425afaf53e3a7baf67675c824ecd4afb7"
    },
    "rivers.geojson": {
      "bytes": 3811255,
      "sha256": "17841a1288723e98d3569d8802d78e087cd80682a5e508b4caffd029c3a0f28b"
    }
  }
}