This section describes the features which make up OS MasterMap Network - Water Layer. The attributes associated with these feature types are listed below along with a brief description of their data properties.
The name of the attribute and what it is describing.
The nature of the attribute, for example a numeric value or a code list value.
Describes how many times this element is expected to be populated in the data. An attribute may be optional or mandatory within the product. These are denoted by:
‘1’ – there must be a value.
‘0..1’ – population is optional but a maximum of one attribute will be returned These values may be used in combination.
HydroNode features explicitly represent the starts, ends and junctions of watercourses, and places where certain attribution changes. They only exist at the end points of the WatercourseLink features. HydroNode positions are provided in 3D. The vertical coordinate has been sourced from Ordnance Survey terrain data.
Definition: A feature at the end of one or more WatercourseLink features that indicates the confluence of two or more watercourses and / or a change in attribution of the connected WatercourseLink features.
Subtype of: HydroNode
The cause of the creation of the current version of the feature.
Attribute name: reasonForChange
Type: ReasonForChangeValue
Multiplicity: [1]
The location of the HydroNode.
Attribute name: geometry
Type: GM_Point
Multiplicity: [1]
External object identifier of the spatial object. The localId contains the Ordnance Survey TOID. An external object identifier is a unique object identifier published by the responsible body, which may be used by external applications to reference the spatial object. The identifier is an identifier of the spatial object, not an identifier of the real-world phenomenon.
Attribute name: inspireId
The identifier of the particular version of the spatial object, with a maximum length of 25 characters. If the specification of a spatial object type with an external object identifier includes life-cycle information, the version identifier is used to distinguish between the different versions of a spatial object. Within the set of all versions of a spatial object, the version identifier is unique.
Attribute name: versionId
Type: CharacterString
Multiplicity: [0..1]
Date and time at which this version of the spatial object was inserted or changed in the spatial data set. This is equivalent to ‘versionDate’ in other OS MasterMap products.
Attribute name: beginLifespanVersion
Type: DateTime
Multiplicity: [1]
Nature of the HydroNode.
Attribute name: hydroNodeCategory
Type: HydroNodeCategoryValue
Multiplicity: [1]
WatercourseLink features represent the alignments of watercourses and have, in the most part, been derived from Ordnance Survey detailed topographic data.
Where the classification or name changes along a watercourse, the network will be split and a HydroNode classified as 'Pseudo' will be created.
A segment that represents part of a watercourse.
The three-dimensional geometry that represents the general alignment of the watercourse.
Attribute name: centrelineGeometry
Type: GM_Curve
Multiplicity: [1]
Indicator that the centreline geometry of the link is a straight line with no intermediate control points – unless the straight line represents the geography in the resolution of the data set appropriately.
Attribute name: ficticious
Type: Boolean
Multiplicity: [1]
The HydroNode coincident with the first vertex for this WatercourseLink.
Attribute name: startNode
Multiplicity: [1]
The HydroNode coincident with the last vertex for this WatercourseLink. On very rare occasions, the end HydroNode may be the same instance as the start HydroNode.
Attribute name: endNode
Multiplicity: [1]
External object identifier of the spatial object. The localId contains the Ordnance Survey TOID. An external object identifier is a unique object identifier published by the responsible body, which may be used by external applications to reference the spatial object. The identifier is an identifier of the spatial object, not an identifier of the real-world phenomenon.
Attribute name: inspireId
Type: Identifier
Multiplicity: [0..1]
The identifier of the particular version of the spatial object, with a maximum length of 25 characters. If the specification of a spatial object type with an external object identifier includes life-cycle information, the version identifier is used to distinguish between the different versions of a spatial object. Within the set of all versions of a spatial object, the version identifier is unique.
Attribute name: versionId
Type: CharacterString
Multiplicity: [0..1]
Date and time at which this version of the spatial object was inserted or changed in the spatial data set. This is equivalent to ‘versionDate’ in other MasterMap products; at present, the time part is always set to zero.
Attribute name: beginLifespanVersion
Type: DateTime
Multiplicity: [1]
The cause of the creation of the current version of the feature.
Attribute name: reasonForChange
Type: ReasonForChangeValue
Multiplicity: [1]
The nature of the watercourse being represented by the feature.
Attribute name: form
Type: WatercourseFormValue
Multiplicity: [1]
A description of the relationship of the watercourse to ground level.
Attribute name: level
Type: VerticalPositionValue
Multiplicity: [1]
The origin of the centrelineGeometry property.
Attribute name: provenance
Type: WatercourseProvenanceValue
Multiplicity: [1]
Direction of water flow in the segment relative to digitisation of segment geometry.
Attribute name: flowDirection
Type: LinkDirectionValue
Multiplicity: [1]
Value indicating the relative importance of the WatercourseLink within any larger watercourse it is part of. Primary flow is indicated as 1; secondary (and all other levels of) flow is indicated as 2. Further levels are not currently indicated. The primary flow was originally calculated using a combination of attributes.
Attribute name: primacy
Type: Integer
Multiplicity: [1]
The code assigned by a responsible body that is used to identify the watercourse. The responsible bodies are Environment Agency for England, the Scottish Environmental Protection Agency for Scotland, and Natural Resources Wales for Wales. Not currently populated.
Attribute name: watercourseNumber
Type: CharacterString
Multiplicity: [0..1]
The name of the watercourse that the WatercourseLink is part of. Where a feature has more than one name, the language of each name is provided as a three-digit ISO 639-2 code (‘eng’, ‘cym’, ‘gla’). See also OS MasterMap Water Network Layer – January 2022 Product Notes. Where a watercourse has a name in more than one language, then this attribute will be the Welsh or Gaelic version.
Attribute name: watercourseName
Type: LocalisedCharacterString
Multiplicity: [0..1]
An alternative name of the watercourse that the WatercourseLink is part of. Where a feature has more than one name, the language of each name is provided as a three-digit ISO 639-2 code (‘eng’, ‘cym’, ‘gla’). See also OS MasterMap Water Network Layer – January 2022 Product Notes. Where a watercourse has a name in more than one language, then this attribute will be the English version.
Attribute name: watercourseNameAlternative
Type: LocalisedCharacterString
Multiplicity: [0..1]
A name that applies to part of a watercourse that is a sub-section of a larger named watercourse that the WatercourseLink is part of. Where a feature has more than one name, the language of each name is provided as a three-digit ISO 639-2 code (‘eng’, ‘cym’, ‘gla’). See also OS MasterMap Water Network Layer – January 2022 Product Notes. Where a watercourse has a local name in more than one language, then this name will be the Welsh or Gaelic version.
Attribute name: localName
Type: LocalisedCharacterString
Multiplicity: [0..1]
An alternative name that applies to part of a watercourse that is a sub-section of a larger named watercourse that the WatercourseLink is part of. Where a feature has more than one name, the language of each name is provided as a three-digit ISO 639-2 code (‘eng’, ‘cym’, ‘gla’). See also OS MasterMap Water Network Layer – January 2022 Product Notes. Where a watercourse has a name in more than one language, then this attribute will be the English version.
Attribute name: localNameAlternative
Type: LocalisedCharacterString
Multiplicity: [0..1]
The name of the catchment area where the WatercourseLink falls, assigned by a responsible body. The responsible bodies are Environment Agency for England, the Scottish Environmental Protection Agency for Scotland, and Natural Resources Wales for Wales.
Attribute name: catchmentName
Type: CharacterString
Multiplicity: [0..1]
The code of the catchment area where the WatercourseLink falls, assigned by a responsible body. The responsible bodies are Environment Agency for England, the Scottish Environmental Protection Agency for Scotland, and Natural Resources Wales for Wales.
Attribute name: catchmentID
Type: CharacterString
Multiplicity: [0..1]
A logical indicator that describes if the watercourse contains water year-round (in normal conditions) or only contains water intermittently. For example, a flood relief channel would have this set to ‘False’.
Attribute name: permanence
Type: Boolean
Multiplicity: [1]
A logical indicator that describes whether the watercourse is managed for inland navigation by a member of The Association of Inland Navigation Authorities (AINA). All values are currently set to false, future releases of the product may include values set to true.
Attribute name: managedNavigation
Type: Boolean
Multiplicity: [1]
Calculated two-dimensional length of network segment in metres. Value supplied to one decimal place.
Attribute name: length
Type: Length
Multiplicity: [1]
A calculated percentage value that indicates the rate of descent of the surface of the water. See Gradient for derivation. Where the gradient does not correlate with the flow, this value is not supplied and a “nilReason” of ‘unknown’ is given.
Attribute name: gradient
Type: Real
Multiplicity: [1]
The average width of the watercourse along the WatercourseLink expressed in metres. This value is void for WatercourseLink features derived from Ordnance Survey large-scales single line features. These values will be given a “nilReason” of ‘unknown’.
Attribute name: width
Type: Distance
Multiplicity: [1]
A calculated value indicating the relative cartographic importance of a WatercourseLink to aid selection and depiction when styling the data. See LevelOfDetail for derivation.
Attribute name: levelOfDetail
Type: LevelOfDetailValue
Multiplicity: [0..1]