Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
Loading...
This technical specification provides detailed technical information about OS MasterMap Water Network Layer. It is targeted at technical users and software developers.
OS MasterMap Water Network Layer provides a three-dimensional structured link and node network of Great Britain's watercourses. A link represents the approximate central alignment of a watercourse and includes inland rivers, streams, tidal water, lakes, lochs and canals; links are attributed with additional information, including flow direction and primary flow paths. Where watercourses are obscured or underground, connectivity is provided where Ordnance Survey capture processes or accepted sources can infer the connection.
The OS MasterMap Water Network Layer product is in geometric sympathy with the underlying topographic features that comprise OS MasterMap Topography Layer. Polygons and lines representing the water area and its banks are not supplied in this product but will continue to be maintained and supplied as part of the OS MasterMap Topography Layer product.
Ordnance Survey provides persistent managed identifiers as TOIDs. TOIDs are strings of up to twenty characters, starting with ‘osgb’; the remaining characters are digits (0 to 9). In an INSPIRE encoded dataset such as this, each feature carries its identifier in three ways, as described below:
gml:id: Required by Geography Markup Language (GML). This matches the pattern in other OS MasterMap products.
gml:identifier: Recommended by INSPIRE and the UK INSPIRE project. This formats the TOID into a persistent URI, using http://data.os.uk/id/ as a namespace, instead of ‘osgb’. This does not mean that the water network features are available as linked data.
net:inspireId: The localId is set to the TOID (without ‘osgb’), and the namespace set as above. The
INSPIRE identifier model does not fit with SF0; it does fit with level 1.
The feature version is encoded as the versionId within the INSPIRE Identifier.
OS MasterMap Water Network Layer will be supplied in Geography Markup Language (GML) 3.2.1, GeoPackage and vector tiles formats.
OS MasterMap Water Network Layer is based on the INSPIRE Hydrography Data Specification, which itself is based on the ISO TC211 family of open standards.
OS MasterMap Water Network Layer extends the INSPIRE specification.
The data structure is described below by means of unified modeling language (UML) class diagrams and accompanying tables containing text. The UML diagrams conform to the approach specified in ISO 19103 Conceptual schema language and ISO 19109 Rules for application schema, as adopted by INSPIRE.
Colour conventions have been used in the diagrams and tables to distinguish the INSPIRE specification from the additional properties that have been added in this specification. In the UML diagram, classes from the INSPIRE Data Specifications are coloured grey, whereas classes in the Ordnance Survey product specification are coloured orange. All code lists are coloured blue, enumerations are coloured green and data types are coloured purple, which can be seen in the figure below. The tables which follow in this Technical Specification use orange for a feature type, blue for a code list, green for enumerations and purple for data types.
This technical specification includes the following sections:
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.
The following page outlines observations made from product testing and observations which are of note to users of the product. Ordnance Survey is working towards fixing these errors for the next release.
The xml:lang attributes are not populated in the product. They are planned for population in a future product release where a feature has more than one name.
The names of watercourses in the product are not all continuous throughout their extent.
There are a number of errors with HydroNode features with the hydroNodeCategory value 'Source' and 'Outlet', where the flowDirection of the connected WatercourseLink is in the wrong direction or is unknown.
There are a number of WatercourseLink features which self-intersect. The vast majority are at the mm level and were created by rounding processes. These will be fixed in a future release.
There are a small number of WatercourseLink features which are shorter in length than 1m. There are a small number of WatercourseLink features which form a closed loop.
There are a number of double digitised WatercourseLink features across the product.
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]
The following documents outline observations made from product testing and observations which are of note to users of the product.
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]
A code list or enumeration is a controlled set of values which can be used to populate a specific column.
This section describes the structured data types which make up OS MasterMap Network - Water Layer. The attributes associated with these data 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.
OS MasterMap Water Network Layer is a topological network representing the watercourses within Great Britain. The product is made up of five feature types:
WatercourseLink: Features that represent the approximate central alignment of a watercourse, including rivers, lakes and canals. They can represent part of a watercourse or a whole watercourse.
HydroNode: Features that represent a river’s source, end, a junction where three or more links meet, and places where the real-world related attribution changes, for example, the point where a watercourse becomes tidal.
WatercourseSeparatedCrossing: Features to indicate the relationships between watercourses that intersect at different levels.
WatercourseLinkSet: Features to represent sets of links, for example, named rivers or watercourses within a catchment area.
WatercourseInteraction: Features that represent events along the water network, for example, weirs and mooring points.
Only two feature types are supplied in the current release of the product: WatercourseLink and HydroNode. This technical specification will cover all five of the feature types which make up the product as all five feature types are referenced in the product schema, which is the controlling specification for the product.
All the feature instances, of whichever feature type, are provided as a single FeatureCollection.
OS MasterMap Water Network Layer has been built with the INSPIRE Hydro – Network Specification as a basis, which results in the product inheriting attribution from INSPIRE. An overview of the product structure can be found in Figure 4, which highlights the inherited INSPIRE feature types and attribution.
Properties of the INSPIRE specification which are voidable and are not being populated in the product have not been included in the class diagrams or the following tables. For information on the INSPIRE properties which are not included in this product, please see the INSPIRE Data Specification on Hydrography – Network application schema.
The linearReference data type will be used where required to record interaction over a length of a WatercourseLink. For example, linear interactions could be used to record where the water network passes under the bridge for a distance at A, over a weir at B or has an associated fish pass at an offset at C.
Where a linear interaction applies to two or more links, then each part of the interaction is recorded by means of more than one networkReference property.
Reference to a part of a WatercourseLink along which a specific property applies.
Subtype of: SimpleLinearReference
Point geometry to explicitly locate the start location from which the property applies.
Attribute name: fromPositionGeometry
Type: GM_Point
Multiplicity: [1]
Point geometry to explicitly locate the end location to which the property applies.
Attribute name: toPositionGeometry
Type: GM_Point
Multiplicity: [1]
The pointReference data types will be used to record interactions at points on the WatercourseLink (interactions with a length of less than 2 m). For example, point interactions could be used to record the presence and position of features such as sluices.
Reference to specific point on a WatercourseLink at which a specific property applies.
Subtype of: SimplePointReference
Point geometry to explicitly locate where on the WatercourseLink the property applies.
Attribute name: atPositionGeometry
Type: GM_Point
Multiplicity: [1]
List of values for flow relative to a WatercourseLink coordinate order
| Code | Description |
|---|
Where the flow direction has not been determined, this attribute is set to null and a ‘nilReason’ is given.
Where the value of nilReason is set to ‘unknown’, then the flow direction is not known to Ordnance Survey. A correct value may exist, but the methods employed by Ordnance Survey to date have not facilitated capture.
Where the value of nilReason is set to ‘missing’, then the flow can be considered indiscernible. Ordnance Survey has attempted to identify the flow on the ground, but no flow has been determined.
bothDirections | Water flows in both directions along the watercourse. |
inDirection | Water flows in the same direction as the order of the coordinate vertices. |
inOppositeDirection | Water flows in the opposite direction to the order of the coordinate vertices. |
Classification value defining the type of WatercourseLink.
| Code | Description |
|---|---|
Where the WatercourseForm has not been determined, this attribute is set to 'null' and the value of nilReason is set to ‘unknown’.
A correct value will exist, but the methods employed by Ordnance Survey to date have not facilitated capture.
This attribute is currently set to a single value of ‘Local’, pending future developments in creating an attribute set in sympathy with OS Open Rivers data.
A calculated value indicating the relative cartographic importance of a WatercourseLink to aid selection and depiction when styling the data.
| Value | Description |
|---|---|
The relative vertical position of a feature.
| Code | Description |
|---|---|
Where the VerticalPosition has not been determined, this attribute is empty, with a nilReason explicitly stated as ‘unknown’. A correct value does exist, but the methods employed by Ordnance Survey to date have not facilitated capture.
The source and/or technique used to create the WatercourseLink feature.
| Code | Description |
|---|---|
A feature may have been obtained from more than one source; where this is the case, the following priority order is used to assign the provenance value:
OS-line or OS-area
localAuthoritySurveyed or nationalAuthoritySurveyed
localAuthorityInferred or nationalAuthorityInferred
inferred
Canal
A manmade watercourse originally created for inland navigation.
Drain
A manmade watercourse whose primary purpose is the removal of excess water from a localised area.
This attribute is not fully populated in this release of the data; however, it will be added to in future data updates.
Foreshore
A watercourse that flows without a well-defined channel over the foreshore (the area between the high and low water marks).
inlandRiver
A river or stream that is not influenced by normal tidal action.
Lake
A large area of non-tidal water without an obvious flow that is enclosed by land.
lockOrFlightOfLocks
An enclosure in a canal or navigable river with a movable gate and sluices at either end. Designed to allow vessels to move between sections of canal or navigable river at different levels by filling or draining the enclosure.
This attribute is not fully populated in this release of the data; however, it will be added to in future data updates. Where watercourses flow through Locks, they are included but may be attributed with a more general term.
Marsh
An area of ground that is predominantly waterlogged by freshwater throughout the year with no identifiable specific alignment for the flow. For the water network, they are captured only where water flows into and out of the marsh and connects to other watercourses.
Reservoir
An area of non-tidal water used for storing water that may be used for irrigation, water supply, power generation or flood control. The area has been created artificially either fully or in part.
This attribute is not fully populated in this release of the data; however, it will be added to in future data updates. Where watercourses flow through Reservoirs they are included but may be attributed with a more general term.
Sea
Tidal water where the influence of inland watercourses is negligible, for example, a wide estuary or the open sea. They are usually included to provide connections for watercourses running into estuaries.
tidalRiver
Watercourses that are subject to the effect of normal tidal action. These exist between the Normal Tidal Limit and Point B (an intangible line where the level of a river meets the level of the sea).
Transfer
A manmade watercourse whose primary purpose is to move water from one location to another (using gravity and / or pumping) typically for water supply or power generation.
Local
A watercourse which is important mainly at a local level, recommended for representation only at scales of 1:20 000 and larger.
District
Not in this release of the product.
A watercourse which is important at a local and district level, recommended for representation only at scales of 1:50 000 and larger.
Regional
Not in this release of the product.
A watercourse which is important at a local, district and regional level, recommended for representation at scales of 1:250 000 and larger.
National
Not in this release of the product.
A watercourse which is important at a national level, recommended for representation at all scales.
New
This is a new feature in the database.
Modified
The feature has been edited by an operator, i.e. the geometry of a feature is changed following real-world change.
Software
Feature has been adjusted by an automatic software process. Includes geometric adjustment, cleaning and reversing direction of digitising.
Reclassified
The classifying attributes of a feature have changed
Restructured
New feature(s) have been created from parts of existing feature(s). Applied to features where a feature is split into two or more features, or when two or more features are joined together.
Attributes
Applied to features that have attributes other than the classifying ones changed.
Position
Correction of position of feature, not related to real-world change.
flowConstriction
A split in the network captured to indicate a hydrographic point of interest or facility, or a man-made object that affects the network flow. This attribute is not manifested in this release of the data; however, it will be utilised in future data updates.
flowRegulation
A split in the network captured to indicate a man-made object that is used to regulate the network flow. This value is not currently supplied.
junction
A split in the network to indicate where three or more WatercourseLink features meet at the same level, for example, confluences or bifurcations.
Outlet
The end terminal of a set of one or more interconnected links that does not have any downstream flow, for example, where a watercourse sinks into the ground or the point where a river enters the sea.
Source
The start terminal of a set of one or more interconnected links that has downstream flow, for example, springs or collects.
Pseudo
A location where the real-world attribution of a watercourse changes that requires a WatercourseLink to be split.
boundary
HydroNode used to connect different networks.
Note: Can be used to connect cross border networks or adjacent networks together. Differs from source / outlet in that in the real world there is an adjacent link that is not present in the dataset supplied.
onGroundSurface
The feature is on ground level.
suspendedOrElevated
The feature is suspended or elevated.
Underground
The feature is underground.
OS-line-Urban
The WatercourseLink is based upon Topographic line features representing watercourses within Ordnance Survey basic scale data, where the line feature was originally captured to an accuracy of 0.5 m RMSE.
See Topographic line and area features for more information.
OS-line-Rural
The WatercourseLink is based upon Topographic line features representing watercourses within Ordnance Survey basic scale data, where the line feature was originally captured to an accuracy of 1.1 m RMSE.
See Topographic Line and Area features for more information.
OS-line-Moorland
The WatercourseLink is based upon Topographic line features representing watercourses within Ordnance Survey basic scale data, where the line feature was originally captured to an accuracy of 4.1 m RMSE.
See Topographic Line and Area features for more information.
OS-area-Urban
The WatercourseLink is based upon Topographic area features representing watercourses within Ordnance Survey basic scale data, where the area feature was originally captured to an accuracy of 0.5 m RMSE.
See Topographic Line and Area features for more information.
OS-area-Rural
The WatercourseLink is based upon Topographic area features representing watercourses within Ordnance Survey basic scale data, where the area feature was originally captured to an accuracy of 1.1 m RMSE.
See Topographic Line and Area features for more information.
OS-area-Moorland
The WatercourseLink is based upon Topographic area features representing watercourses within Ordnance Survey basic scale data, where the area feature was originally captured to an accuracy of 4.1 m RMSE.
See Topographic Line and Area features for more information.
Inferred
A WatercourseLink where the alignment has been added by deduction from existing Ordnance Survey Topographic features or terrain data to provide an indicative connection between other WatercourseLink features.
localAuthorityInferred
A WatercourseLink provided by a local authority that has not been measured or otherwise confirmed on the ground, but which has been added to provide an indicative connection between other WatercourseLink features.
localAuthoritySurveyed
A WatercourseLink provided by a local authority that has been measured or otherwise confirmed on the ground.
nationalAuthorityInferred
A WatercourseLink provided by an accepted national authority that has not been measured or otherwise confirmed on the ground, but which has been added to provide an indicative connection between other WatercourseLink features.
nationalAuthoritySurveyed
A WatercourseLink provided by an accepted national authority that has been measured or otherwise confirmed on the ground.
catchment | The area drained by a watercourse and its tributaries that enters the sea, a lake or a sink where no further flow is identified. Supplied by the Environment Agency for England, the Scottish Environmental Protection Agency for Scotland, and Natural Resources Wales for Wales. |
waterBody | A water body defined under the Water Framework Directive (WFD). |
watercourse | A watercourse with an accepted proper name in common use. |
Not currently populated in this release of OS MasterMap Water Network Layer.
A feature that allows the supply of additional information related to the network in addition to the attribution and geometry of WatercourseLink features. For example, where a watercourse passes under a bridge or over a weir.
A feature that describes an event along a watercourse related to the water network that cannot be indicated by the attribution or geometry of the WatercourseLink or HydroNode feature(s).
Subtype of: NetworkProperty
Reason for the current version to be created.
Attribute name: reasonForChange
Type: ReasonForChangeValue
Multiplicity: [1]
Not currently populated in OS MasterMap Water Network Layer.
Attribute name: watercourseInteractionCategory
Type: HydroNodeCategoryValue
Multiplicity: [1]
Interactions can be either PointReference (for interactions less than 2 m in length) or LinearReference (for interactions more than 2 m in length). These record the position along a specified WatercourseLink for a point interaction, or the start and end position along one or more links for a linear interaction.
Interactions can be recorded with an offset indicating which side of the WatercourseLink the interaction is and a distance.
OS MasterMap Water Network Layer is supplied as a single GeoPackage for the whole of Great Britain. GeoPackage (*.gpkg) is an open, non-proprietary, platform-independent, standards-based data format for geographic information systems (GIS), as defined by the Open Geospatial Consortium (OGC). It is designed to be a lightweight format that can contain large amounts of varied and complex data in a single, easy-to-distribute and ready-to-use file. GeoPackage is natively supported by numerous software applications.
GeoPackage offers users the following benefits:
The single file is easy to transfer and offers the end-user a rich experience.
Attribute names are not limited in length, making the format user-friendly.
The file size limit is very large at 140 TB (A file size limit might be imposed by the file system to which the file is written).
It supports raster, vector and database formats, making it a highly versatile solution.
It is an OGC standard.
In most cases, it is a plug-and-play format.
For information on how to open, use and understand a GeoPackage dataset, please refer to our ‘Getting Started with GeoPackage’ guide. Further detailed information on GeoPackage can be taken from the GeoPackage website.
The naming of attributes between GeoPackage and the Geography Markup Language (GML) file is very similar as GeoPackage files are not limited in the number of characters for an attribute name. Therefore, the tables included here map the GML attribute name to the attribute name in the GeoPackage files.
The GML contains an attribute which describes the geometry of the feature; this is not applicable for a GeoPackage file as they are separated by their geometry.
Please note that the use of an asterisk symbol (*) in the following tables indicates that a particular attribute is not mapped to GML.
Not currently populated in this release of OS MasterMap Water Network Layer.
This spatial object type is included for future use to record sets of links that when combined create a recognisable identifiable watercourse, for example, a named river or a canal.
A feature recording a set of watercourse links representing an identifiable watercourse.
Subtype of: LinkSet
The cause of the creation of the current version of the feature.
Attribute name: reasonForChange
Type: ReasonForChangeValue
Multiplicity: [1]
Official code assigned to identify the watercourse. This is an official identification code assigned by a responsible authority, such as the Environment Agency (EA) or the Scottish Environmental Protection Agency (SEPA).
Attribute name: watercourseNumber
Type: CharacterString
Multiplicity: [0..1]
The name of the watercourse that the WatercourseLinkSet is representing. Note 1: 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'). Note 2: 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 WatercourseLinkSet is representing. Note 1: 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'). Note 2: 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]
The type of watercourse that the WatercourseLinkSet represents.
Attribute name: watercourseType
Type: WatercourseTypeValue
Multiplicity: [1]
The following three feature types (WatercourseSeparatedCrossing, WatercourseLinkSet and WatercourseInteraction) are not currently populated in the current version of OS MasterMap Water Network Layer; however, they are referenced in the product’s schema which is the controlling specification for the product. The intention is to add these three feature types into future versions of the product.
The Geography Markup Language (GML) data conforms to GML Simple Features Profile Level 1. In this release of the product, the only thing that does not conform to level 0 is the inspireId.
The geometries that we use are OGC ‘simple’: points, and line strings with linear interpolation.
XML schemas are used to define and validate the format and content of the GML. The GML 3.2.1 specification provides a set of schemas that define the GML feature constructs and geometric types. These are designed to be used as a basis for building application-specific schemas, which define the data content.
The Ordnance Survey application schema waterNetwork.xsd, which is referenced by the data, is available on our website. It imports the INSPIRE Hydrography networks application schema, which in turn imports the GML 3.2.1 schemas. These in turn import schemas produced by the W3C. The data contains elements and attributes from a range of namespaces:
| Namespace identifier | Short form prefix | Application schema |
|---|---|---|
| GML attribute | GeoPackage attribute |
|---|---|
Not currently populated in this release of OS MasterMap Water Network Layer.
A feature used to indicate the relationship between watercourses that pass over one another without interaction. The WatercourseLink features are not broken at these locations, and the WaterCourseSeparatedCrossing feature is used to describe the vertical sequence of WatercourseLink features.
A feature that indicates two or more watercourses which pass over one another at different physical levels.
Subtype of: WatercourseSeparatedCrossing
Sequence of crossing links. The order reflects their elevation; the first WatercourseLink is the lower WatercourseLink.
Association Role: element
Multiplicity: [2..*]
Reason for the current version to be created
Attribute name: reasonForChange
Type: ReasonForChangeValue
Multiplicity: [1]
Point where two or more WatercourseLink features intersect.
Attribute name: geometry
Type: GM_Point
Multiplicity: [1]
| GML attribute | GeoPackage attribute |
|---|
| GML attribute | Vector tiles attribute |
|---|
water
OS MasterMap Water Network Layer
urn:x-inspire:specification:gmlas:HydroNetwork:3.0
hy-n
INSPIRE Hydrography networks
urn:x-inspire:specification:gmlas:Network:3.2
net
INSPIRE generic network
urn:x-inspire:specification:gmlas:BaseTypes:3.2
base
INSPIRE base types
gml
OGC GML 3.2.1
xlink
W3C XML Linking
xsi
W3C XML Schema instance
fid
*
gml_id
toid
identifier
identifier
reasonForChange
reason_for_change
centrelinegeometry
geometry
localId
local_id
versionId
version_id
beginLifespanVersion
begin_lifespan_version
hydronodecategory
hydronode_category
fid | * |
gml_id | toid |
identifier | identifier |
centrelinegeometry | geometry |
fictitious | fictitious |
startNode | start_node |
endNode | end_node |
localId | local_id |
versionId | version_id |
beginLifespanVersion | begin_lifespan_version |
reasonForChange | reason_for_change |
form | form |
level | level |
provenance | provenance |
flowDirection | flow_direction |
primacy | primacy |
watercourseNumber | watercourse_number |
watercourseName | watercourse_name |
watercourseNameLang | watercourse_name_lang |
watercourseNameAlternative | watercourse_name_alternative |
watercourseNameAlternativeLang | watercourse_name_alternative_lang |
localName | local_name |
localNameLang | local_name_lang |
localNameAlternative | local_name_alternative |
localNameAlternativeLang | local_name_alternative_lang |
catchmentName | catchment_name |
catchmentID | catchment_id |
permanence | permanence |
managedNavigation | managed_navigation |
length | length |
length_uom | length_uom |
gradient | gradient |
width | width |
width_uom | width_uom |
levelOfDetail | level_of_detail |
gml_id | toid |
hydronodecategory | hydronode_category |
Further information about the product can be found on:
The product's Getting Started Guide focuses solely on using the product in Geography Markup Language (GML) format.
The product's Getting Started Guide focuses solely on using the product in GML format.
Data was created from Ordnance Survey large-scale data with additional input from recognised bodies.
In OS MasterMap Topography Layer, watercourses with less than specified widths are captured as single line features for cartographic clarity purposes. These dimensions are 1 m in urban areas, 2 m in rural areas and 5 m in mountain and moorland areas.
For watercourses captured as area features, algorithms were used to create a network, including generating topological connections if appropriate. Additional connecting geometry has been added to ensure topological connectivity where this can be deduced by inspection.
Watercourses represented by line features were used to generate network lines and these were extended both automatically and manually to indicate connectivity.
Manual improvement was undertaken where validation identified issues with flow and connectivity, and as a result of customer feedback.
This section describes how attributes are derived from other information contained within Ordnance Survey large-scale data.
The width attribute is calculated to provide an average width of the Topographic Area feature(s) used to create the network links. There may be significant variation along the portion of the watercourse represented by a WatercourseLink with a single width attribute.
The majority of links in the data were sourced from Ordnance Survey detailed topographic data. Different depictions within Ordnance Survey detailed topographic data are adopted for cartographic clarity purposes, and watercourses may be represented as lines or areas. Watercourses with less than specified widths are captured as single line features, while watercourses with greater than specified widths are captured as area features.
| Locality | Width | Topographic representation | Width attribute |
|---|
Advances in data capture techniques mean that the cartographic constraints on capture as area features are now less pronounced. As a result, some features below the minimum widths in the table above may have been captured as areas.
Definition: A calculated value indicating the relative cartographic importance of a WatercourseLink to aid selection and depiction when styling the data.
Currently, this has been populated with a single value pending the development of algorithms to create more usable attribution.
The Primacy attribute is derived by assessing a combination of the flow, width, gradient and length of the network WatercourseLink feature to identify the most likely course of the main flow of a watercourse at bifurcations.
Gradient is a calculated attribute that indicates the rate of descent of the surface of the water over the entire length of the WatercourseLink.
Gradient is expressed as a percentage or drop in metres per 100 metres of WatercourseLink length.
Gradient = (Height on first vertex – Height on last vertex * 100) / Planar length of link
For more detailed analysis of the WatercourseLink, height is provided on each vertex that can allow a user to calculate gradients within sections of the WatercourseLink.
The water network was heighted by interpolation from a bare earth terrain comprising mass points and breaklines. The highest resolution height information available was used in this process. This terrain was captured by Ordnance Survey recently and is the basis for new products that include a height component.
The data used to height the network is of a resolution and quality that in some cases results in height attribution that contradicts the flow attribution. This is typically in areas with little change in elevation. In these cases, the calculated gradient attribute will not be supplied.
Future developments will reduce occurrences by improving the terrain data to reflect the influence of watercourses on the terrain surface.
Urban | <1.0m | line | null |
Urban | +>1.0m | area | calculated |
Rural | <2.0m | line | null |
Rural | +>2.0m | area | calculated |
Mountain and moorland | <5.0m | line | null |
Mountain and moorland | +>5.0m | area | calculated |
| GML attribute | Vector tiles attribute |
|---|---|
gml_id
toid
fictitious
fictitious
form
form
level
level
provenance
provenance
flowDirection
flow_direction
primacy
primacy
watercourseNumber
watercourse_number
watercourseName
watercourse_name
watercourseNameAlternative
watercourse_name_alternative
localNameLang
local_name
localNameAlternative
local_name_alternative
catchmentName
catchment_name
Permanence
permanence
managedNavigation
managed_navigation
length
length
length_uom
length_uom
gradient
gradient
width
width
width_uom
width_uom
levelOfDetail
level_of_detail
For guidance on using the product in GeoPackage format, please see theGetting started with GeoPackage guide.
For guidance on using the product in vector tiles format, please see the .
OS MasterMap Water Network Layer is supplied as a national vector tiles set in a single MBTiles file. This is a lightweight set of tiles that are efficient and fast to render in your software, and which provide high- resolution data and give a seamless experience when zooming in and out. The data is supplied in Web Mercator projection (ESPG:3857).
The naming of attributes between vector tiles and the Geography Markup Language (GML) file is very similar as the vector tiles set within the MBTiles file is not limited in the number of characters for an attribute name. The following tables map the GML attribute name to the attribute name in the vector tiles.
The vector tiles schema is detailed in the following table. In the zoom levels columns within the table, the letter N indicates that the specified layer and attribute are not mapped within that zoom level, whereas the letter Y indicates that the specified later and attribute are mapped within that zoom level.
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
|---|---|---|---|---|---|---|---|---|
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
|---|---|---|---|---|---|---|---|---|
toid
N
Y
Y
Y
Y
Y
Y
Y
fictitious
N
Y
Y
Y
Y
Y
Y
Y
form
N
Y
Y
Y
Y
Y
Y
Y
level
N
Y
Y
Y
Y
Y
Y
Y
provenance
N
Y
Y
Y
Y
Y
Y
Y
flow_direction
N
Y
Y
Y
Y
Y
Y
Y
primacy
N
Y
Y
Y
Y
Y
Y
Y
watercourse_number
N
Y
Y
Y
Y
Y
Y
Y
watercourse_name
N
Y
Y
Y
Y
Y
Y
Y
watercourse_name_alternative
N
Y
Y
Y
Y
Y
Y
Y
local_name
N
Y
Y
Y
Y
Y
Y
Y
local_name_alternative
N
Y
Y
Y
Y
Y
Y
Y
catchment_name
N
Y
Y
Y
Y
Y
Y
Y
permanence
N
Y
Y
Y
Y
Y
Y
Y
managed_navigation
N
Y
Y
Y
Y
Y
Y
Y
length
N
Y
Y
Y
Y
Y
Y
Y
length_uom
N
Y
Y
Y
Y
Y
Y
Y
gradient
N
Y
Y
Y
Y
Y
Y
Y
width
N
Y
Y
Y
Y
Y
Y
Y
width_uom
N
Y
Y
Y
Y
Y
Y
Y
level_of_detail
N
Y
Y
Y
Y
Y
Y
Y
toid
N
Y
Y
Y
Y
Y
Y
Y
hydonode_category
N
Y
Y
Y
Y
Y
Y
Y
