documentation generated from TS

For the purposes of the present document, the following abbreviations apply:

* EC: European Commission

* M-Bus: Meter-Bus

* OWL-DL: Web Ontology Language - Description Logics

* RDF: Resource Description Framework

* RDF-S: Resource Description Framework Schema 

* SAREF: Smart Applications REFerence ontology

* SAREF4SYST: SAREF extension for Systems

* SAREF4WATR: SAREF extension for the Water domain

* WKT: Well-Known Text

 No newline at end of file

# SAREF4WATR ontology and semantics

## Introduction and overview

The present document is a technical specification of SAREF4WATR, an extension of SAREF for the Water

domain. This extension has been created by investigating resources from potential stakeholders of the ontology, such as standardization initiatives, associations, European projects, EC directives, existing ontologies, and data repositories, as reported in ETSI TR 103 547 [i.1]. In addition, the use cases defined in [i.1] were also taken into account, namely:

* **Use case 1**: Remote reading of metrological registers

* **Use case 2**: Advanced meter reading and configuration

* **Use case 3**: Risk management over water critical infrastructure

* **Use case 4**: Interaction of cross-domain variables and models for policy-making

Taking into account ontologies, data models, standards and datasets provided by the identified stakeholders, a set of requirements were identified and grouped in the following categories: Water infrastructure, Water meter, Meter measurements, Infrastructure measurements, Water measurements, Indicators, and Tariff. Such requirements and categories were validated during the "SAREF4WATR Validation Workshop" at the ICT4Water Cluster annual event in Brussels on 11<sup>th</sup> June 2019. During the workshop, attendees validated the use cases proposed above and the list of requirements for the above-mentioned categories. According to the feedback and outcomes of the workshop, some actions were taken such as to better define the geolocation of meters or to allow connecting information from the water domain to other domains. The concrete decisions were reported in ETSI TR 103 547 [i.1]. The requirements listed in ETSI TR 103 547 were taken as input for the ontology development. 

SAREF4WATR is an OWL-DL ontology that extends SAREF and reuses six other ontologies. SAREF4WATR includes 54 classes (40 defined in SAREF4WATR and 14 reused from the SAREF, SAREF4CITY, SAREF4SYST, time, geosp, and sf), 34 object properties (8 defined in SAREF4WATR and 26 reused from SAREF, SAREF4CITY, SAREF4SYST, and geosp), 19 data type properties (12 defined in SAREF4WATR and 7 reused from SAREF and SAREF4CITY), and 65 individuals. 

SAREF4WATR focuses on extending SAREF in order to create a common core of general concepts for water data oriented to the IoT field. The main idea is to identify the core components, as mentioned, that could be extended for particular water subdomains, for example, for water supply.

The prefixes and namespaces used in SAREF4WATR and in the present document are listed in Table 1.

{{table_1}}

<p>This document presents the implementation of the SAREF extension for the water domain (SAREF4WATR) which based on a limited set of use cases and from available existing data models. This work has been developed in the context of the <a href="https://portal.etsi.org/STF/STFs/STF-HomePages/STF566">STF 566</a> which was established with the goal to create SAREF extensions for the domains of automotive, eHealth and ageing well, wearables, and water.</p>

<h3>General overview</h3>

<p><a href="#Figure_1">Figure 1</a> and <a href="#Figure_2">Figure 2</a> present an overview of the classes and the properties included in the SAREF4WATR extension.</p>

<figure>

  <a href="diagrams/SAREF4WATR Overview 1.png"><img src="diagrams/SAREF4WATR Overview 1.png" alt="SAREF4WATR overview. Measurements and KPIs"/></a>

  <figcaption id="Figure_1">Figure 1: SAREF4WATR overview. Measurements and KPIs</figcaption>

</figure>

<figure>

  <a href="diagrams/SAREF4WATR Overview 2.png"><img src="diagrams/SAREF4WATR Overview 2.png" alt="SAREF4WATR overview. Water-related terms"/></a>

  <figcaption id="Figure_1">Figure 2: SAREF4WATR overview. Water-related terms</figcaption>

</figure>

<h3>Measurement</h3>

<p>As it can be observed in <a href="#Figure_3">Figure 3</a>, the modelling of measurements in the SAREF4WATR ontology mostly relies on the measurement model proposed in SAREF.</p>

<p>SAREF allows to define the temporal extent of a measurement by defining the timestamp for it (using the <a href="https://saref.etsi.org/core/hasTimestamp">saref:hasTimestamp</a> property). However, the SAREF4WATR extension also required to be able to define the temporal interval to which a measurement applies, apart from the temporal instant defined by the timestamp. Therefore, the <a href="#s4watr:hasPhenomenonTime">s4watr:hasPhenomenonTime</a> property has been defined in this extension to define the time for which the measurement applies to a feature of interest. The range of this property time has been defined as a time:TemporalEntity, which allows defining temporal intervals or instants.</p>

<p>Besides, the extension requires to be able to represent those devices that measure a certain feature of interest (and those features of interest that are measured by a device) independently of having measures from which this relationship could be inferred. Because of this, in this extension we have created four new properties to relate <a href="https://saref.etsi.org/core/Device">saref:Device</a> and <a href="https://saref.etsi.org/core/FeatureOfInterest">saref:FeatureOfInterest</a>: <a href="#s4watr:featureIsMeasuredByDevice">s4watr:featureIsMeasuredByDevice</a>, <a href="#s4watr:featureIsControlledByDevice">s4watr:featureIsControlledByDevice</a>, <a href="#s4watr:measuresFeature">s4watr:measuresFeature</a>, and <a href="#s4watr:controlsFeature">s4watr:controlsFeature</a>.</p>

<figure>

  <a href="diagrams/SAREF4WATR Measurement.png"><img src="diagrams/SAREF4WATR Measurement.png" alt="Measurement model"/></a>

  <figcaption id="Figure_3">Figure 3: Measurement model</figcaption>

</figure>

<h3>Water meter</h3>

<p><a href="#Figure_4">Figure 4</a> provides an overview of how to represent a water meter using the <a href="#s4watr:WaterMeter">s4watr:WaterMeter</a> class. The representation of water meters and their properties has been extracted from the European M-Bus standard (EN 13757).</p>

<p>A water meter may be defined by the properties inherited from SAREF (e.g., <a href="https://saref.etsi.org/core/hasManufacturer">saref:hasManufacturer</a> or <a href="https://saref.etsi.org/core/hasModel">saref:hasModel</a>) and also by a set of properties defined in SAREF4WATR to indicate: its fabrication number (<a href="#s4watr:hasFabricationNumber">s4watr:hasFabricationNumber</a>), its firmware version (<a href="#s4watr:hasFirmwareVersion">s4watr:hasFirmwareVersion</a>), its hardware version (<a href="#s4watr:hasHardwareVersion">s4watr:hasHardwareVersion</a>), its version (<a href="#s4watr:hasVersion">s4watr:hasVersion</a>), the radio frequency in which it operates (<a href="#s4watr:operatesAtRadioFrequency">s4watr:operatesAtRadioFrequency</a>), and its required power (<a href="#s4watr:requiresPower">s4watr:requiresPower</a>).</p>

<p>Measurements may be taken from the water meter themselves. To enable the representation of such measurements, water meters are defined as features of interest (<a href="https://saref.etsi.org/core/FeatureOfInterest">saref:FeatureOfInterest</a>) and a non-exhaustive list of properties has been defined based on the M-Bus standard to allow measuring: on time (<a href="#s4watr:MeterOnTime">s4watr:MeterOnTime</a>), operating time (<a href="#s4watr:MeterOperatingTime">s4watr:MeterOperatingTime</a>), battery operating time (<a href="#s4watr:BatteryOperatingTime">s4watr:BatteryOperatingTime</a>), battery last change (<a href="#s4watr:BatteryLastChange">s4watr:BatteryLastChange</a>), and battery remaining time (<a href="#s4watr:BatteryRemainingTime">s4watr:BatteryRemainingTime</a>).</p>

<figure>

  <a href="diagrams/SAREF4WATR Water meter.png"><img src="diagrams/SAREF4WATR Water meter.png" alt="Water meter model"/></a>

  <figcaption id="Figure_4">Figure 4: Water meter model</figcaption>

</figure>

<h3>Water flow</h3>

<p>Water meters are mainly intended to measure water flows. SAREF4WATR defines the main properties related to the water flow that are defined in the European M-Bus standard (EN 13757): pressure (<a href="#s4watr:FlowPressure">s4watr:FlowPressure</a>), rate (<a href="#s4watr:FlowRate">s4watr:FlowRate</a>), temperature(<a href="#s4watr:FlowTemperature">s4watr:FlowTemperature</a>), and volume(<a href="#s4watr:FlowVolume">s4watr:FlowVolume</a>). These properties are depicted in <a href="#Figure_5">Figure 5</a>.</p>

<figure>

  <a href="diagrams/SAREF4WATR Water flow.png"><img src="diagrams/SAREF4WATR Water flow.png" alt="Water flow model"/></a>

  <figcaption id="Figure_5">Figure 5: Water flow model</figcaption>

</figure>

<p>There are also other environmental factors that are relevant since they affect water and the infrastructures using it. Therefore, the following environmental properties, depicted in <a href="#Figure_6">Figure 6</a>, are defined: atmospheric pressure (<a href="#s4watr:AtmosphericPressure">s4watr:AtmosphericPressure</a>), humidity (<a href="#s4watr:Humidity">s4watr:Humidity</a>), precipitation (<a href="#s4watr:Precipitation">s4watr:Precipitation</a>) and temperature (<a href="#s4watr:ExternalTemperature">s4watr:ExternalTemperature</a>).</p>

<figure>

  <a href="diagrams/SAREF4WATR Environmental property.png"><img src="diagrams/SAREF4WATR Environmental property.png" alt="Environmental properties model"/></a>

  <figcaption id="Figure_6">Figure 6: Environmental properties model</figcaption>

</figure>

<h3>Tariff</h3>

<p>SAREF4WATR allows describing the tariff that is applied to a water meter by means of the <a href="#s4watr:Tariff">s4watr:Tariff</a> class, as presented in <a href="#Figure_7">Figure 7</a>. The representation of tariffs has been extracted from the CEN/TR 17167 technical report.</p>

<p>A tariff may be described using different properties to describe its: start timestamp (<a href="#s4watr:hasStartTimestamp">s4watr:hasStartTimestamp</a>), duration (<a href="#s4watr:hasDuration">s4watr:hasDuration</a>), period (<a href="#s4watr:hasPeriod">s4watr:hasPeriod</a>), billing date (<a href="#s4watr:hasBillingDate">s4watr:hasBillingDate</a>), and billing period (<a href="#s4watr:hasBillingPeriod">s4watr:hasBillingPeriod</a>). Besides, a tariff can be related to a water meter by means of the <a href="#s4watr:appliesTo">s4watr:appliesTo</a> property.

There are different types of tariffs, depending on whether they are based on thresholds (<a href="#s4watr:ThresholdBasedTariff">s4watr:ThresholdBasedTariff</a>), consumption (<a href="#s4watr:ConsumptionBasedTariff">s4watr:ConsumptionBasedTariff</a>), or time (<a href="#s4watr:TimeBasedTariff">s4watr:TimeBasedTariff</a>). Each of these types of tariffs has its own properties: for threshold-based ones their volume flow can be defined (<a href="#s4watr:forVolumeFlow">s4watr:forVolumeFlow</a>), for consumption-based ones their volume and financial consumption can be defined (<a href="#s4watr:forVolumeConsumption">s4watr:forVolumeConsumption</a> and <a href="#s4watr:forFinancialConsumption">s4watr:forFinancialConsumption</a>, respectively), and for time-based ones their absolute time at day, week day and day in month can be defined (<a href="#s4watr:forAbsoluteTimeAtDay">s4watr:forAbsoluteTimeAtDay</a>, <a href="#s4watr:forWeekDay">s4watr:forWeekDay</a> and <a href="#s4watr:forDayInMonth">s4watr:forDayInMonth</a>, respectively). It is also possible to define a combined tariff by making it an instance of more than one type of tariff.</p>

<figure>

  <a href="diagrams/SAREF4WATR Tariff.png"><img src="diagrams/SAREF4WATR Tariff.png" alt="Tariff model"/></a>

  <figcaption id="Figure_7">Figure 7: Tariff model</figcaption>

</figure>

<h3>Water types</h3>

<p>SAREF4WATR defines four types of water as instances of the <a href="#s4watr:Water">s4watr:Water</a> class: raw water (<a href="#s4watr:RawWater">s4watr:RawWater</a>), drinking water (<a href="#s4watr:DrinkingWater">s4watr:DrinkingWater</a>), storm water (<a href="#s4watr:StormWater">s4watr:StormWater</a>), and waste water (<a href="#s4watr:WasteWater">s4watr:WasteWater</a>). All these types of water, depicted in <a href="#Figure_8">Figure 8</a>, are defined as features of interest (<a href="https://saref.etsi.org/core/FeatureOfInterest">saref:FeatureOfInterest</a>), so measurements and key performance indicators can be defined over them.</p>

<figure>

  <a href="diagrams/SAREF4WATR Water types.png"><img src="diagrams/SAREF4WATR Water types.png" alt="Water types model"/></a>

  <figcaption id="Figure_8">Figure 8: Water types model</figcaption>

</figure>

<h3>Water properties</h3>

<p>SAREF4WATR includes a classification of the different water properties based on the classification proposed by the World Health Organization, as shown in <a href="#Figure_9">Figure 9</a>. Water properties (<a href="#s4watr:WaterProperty">s4watr:WaterProperty</a>) are classified into acceptability (<a href="#s4watr:AcceptabilityProperty">s4watr:AcceptabilityProperty</a>), chemical (<a href="#s4watr:ChemicalProperty">s4watr:ChemicalProperty</a>), and microbial (<a href="#s4watr:MicrobialProperty">s4watr:MicrobialProperty</a>) ones, being bacterial (<a href="#s4watr:BacterialProperty">s4watr:BacterialProperty</a>) properties a subclass of microbial ones. 

The extension defines different individuals for each type of water property, based in different EC directives on the quality of drinking water, bathing water, and groundwater. This list of individuals does not aim to be exhaustive but to reflect the potential use of the ontology. Note, for example, that it is out of the scope to categorize chemical compounds according to their intended use (e.g., pesticide, fertilizer, etc.).</p>

<figure>

  <a href="diagrams/SAREF4WATR Water property.png"><img src="diagrams/SAREF4WATR Water property.png" alt="Water properties model"/></a>

  <figcaption id="Figure_9">Figure 9: Water properties model</figcaption>

</figure>

<h3>Water infrastructure</h3>

<p>In SAREF4WATR water infrastructures can be defined using the <a href="#s4watr:WaterInfrastructure">s4watr:WaterInfrastructure</a> class. Such infrastructures may be designed for one of the water types described above (through the <a href="#s4watr:isDesignedFor">s4watr:isDesignedFor</a> property), may have an intended use (through the <a href="#s4watr:isIntendedFor">s4watr:isIntendedFor</a> property), and may be classified into five different types, although others may be defined if needed: distribution systems (<a href="#s4watr:DistributionSystem">s4watr:DistributionSystem</a>), storage infrastructures (<a href="#s4watr:StorageInfrastructure">s4watr:StorageInfrastructure</a>), treatment plants (<a href="#s4watr:TreatmentPlant">s4watr:TreatmentPlant</a>), hydroelectric power plants (<a href="#s4watr:HydroelectricPowerPlant">s4watr:HydroelectricPowerPlant</a>), and monitoring infrastructures (<a href="#s4watr:MonitoringInfrastructure">s4watr:MonitoringInfrastructure</a>).</p>

<p>In order to represent the topology of a water infrastructure or its assets, the GeoSPARQL ontology has been reused and connected to the SARE4WATR terms. As shown in <a href="#Figure_10">Figure 10</a>, for representing spatial objects the geosp:SpatialObject class from GeoSPARQL has been reused along with its subclasses that allow defining spatial features (geosp:Feature) and geometries (geosp:Geometry). Different properties from GeoSPARQL can be reused to define spatial relations among spatial objects (e.g., geosp:sfContains, or geosp:sfWithin)or to define the geometry of a feature (geosp:hasGeometry). Two types of geometries from the GeoSPARQL Simple Features ontology are proposed to be used: points (sf:Point) and polygons (sf:Polygon), although others may also be used from that same ontology or from another one.

We refer to the GeoSPARQL standard for further details on how to define the topology of water infrastructures.</p>

<figure>

  <a href="diagrams/SAREF4WATR Water infrastructure.png"><img src="diagrams/SAREF4WATR Water infrastructure.png" alt="Water infrastructure model"/></a>

  <figcaption id="Figure_10">Figure 10: Water infrastructure model</figcaption>

</figure>

<p>By reusing the SAREF4SYST ontology, the different subsystems of a water infrastructure may be defined. A water infrastructure is a complex system (<a href="https://saref.etsi.org/saref4syst/System">s4syst:System</a>) and each of its subsystems may be defined (using the <a href="https://saref.etsi.org/saref4syst/hasSubSystem">s4syst:hasSubSystem</a> property) as a water asset (<a href="#s4watr:WaterAsset">s4watr:WaterAsset</a>).</p>

<p>As shown in <a href="#Figure_11">Figure 11</a>, SAREF4WATR defines the main types of water assets found in the literature in a hierarchy that is not intended to be exhaustive and that may be extended if needed. This hierarchy classifies water assets into source assets (<a href="#s4watr:SourceAsset">s4watr:SourceAsset</a>), sink assets (<a href="#s4watr:SinkAsset">s4watr:SinkAsset</a>), storage assets (<a href="#s4watr:StorageAsset">s4watr:StorageAsset</a>), and transport assets (<a href="#s4watr:TransportAsset">s4watr:TransportAsset</a>).</p>

<p>A dedicated class has been defined for water devices (<a href="#s4watr:WaterDevice">s4watr:WaterDevice</a>), which are those water assets that are also devices according to SAREF (<a href="https://saref.etsi.org/core/Device">saref:Device</a>). A water meter, described above, is one special type of water device, among other possible water-related sensors and actuators.</p>

<figure>

  <a href="diagrams/SAREF4WATR Water asset.png"><img src="diagrams/SAREF4WATR Water asset.png" alt="Water asset model"/></a>

  <figcaption id="Figure_11">Figure 11: Water asset model</figcaption>

</figure>

<h3>Key Performance Indicator</h3>

<p><a href="#Figure_12">Figure 12</a> provides an overview of the modelling of Key Performance Indicators (KPI). The KPI modelling involves two main concepts, namely <a href="https://saref.etsi.org/saref4city/KeyPerformanceIndicator">s4city:KeyPerformanceIndicator</a> and <a href="https://saref.etsi.org/saref4city/KeyPerformanceIndicatorAssessment">s4city:KeyPerformanceIndicatorAssessment</a>. As can be seen in the figure, the modelling of KPIs in SAREF4WATR totally relies on the KPI model proposed in SAREF4CITY.</p>

<p>In SAREF4WATR, KPIs are intended to be defined for water infrastructures (<a href="#s4watr:WaterInfrastructure">s4watr:WaterInfrastructure</a>). However, KPIs may also be defined for other features of interest.</p>

<figure>

  <a href="diagrams/SAREF4WATR Key Performance Indicator.png"><img src="diagrams/SAREF4WATR Key Performance Indicator.png" alt="Key Performance Indicator model"/></a>

  <figcaption id="Figure_12">Figure 12: Key Performance Indicator model</figcaption>

</figure>