documentation generated from TS

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

* EC: European Commission

* KPI: Key Performance Indicator

* 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

<div class="alert-warning">NOTE: The text in this section is extracted from ETSI TS 103 410-10 (V2.1.1) <a href="#[0]">[0]</a>, and therefore falls inside the <a href="https://www.etsi.org/intellectual-property-rights">ETSI IPR Policy</a></div>

# SAREF4WATR ontology and semantics

## Introduction and overview

The present document is a technical specification of SAREF4WATR, an OWL-DL ontology that extends SAREF for the Water domain. 

SAREF4WATR V2.1.1 is a major revision of SAREF4WATR, using updated reference ontology patterns specified in ETSI TS 103 548 <a href="#[3]">[3]</a>  to solve the harmonization needs identified in ETSI TR 103 781 <a href="#[i.9]">[i.9]</a> , with updated development framework and tools defined in ETSI TS 103 673 <a href="#[i.10]">[i.10]</a> .

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 <a href="#[i.1]">[i.1]</a> . In addition, the use cases defined in <a href="#[i.1]">[i.1]</a>  were also taken into account, namely:

SAREF4WATR V2.1.1 is a major revision of SAREF4WATR, using updated reference ontology patterns specified in ETSI TS 103 548 [3] to solve the harmonization needs identified in ETSI TR 103 781 [i.9], with updated development framework and tools defined in ETSI TS 103 673 [i.10].

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

* **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 observations, Infrastructure observations, Water observations, 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 [i.1] were taken as input for the ontology development. 

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 observations, Infrastructure observations, Water observations, Indicators, and Tariff. Such requirements and categories were validated during the "SAREF4WATR Validation Workshop" at the ICT4Water Cluster annual event in Brussels on 11th 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 <a href="#[i.1]">[i.1]</a> . The requirements listed in ETSI TR 103 547 <a href="#[i.1]">[i.1]</a>  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, geo, and sf), 34 object properties (8 defined in SAREF4WATR and 26 reused from SAREF, SAREF4CITY, SAREF4SYST, and geo), 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 [the Namespace Declarations section](#namespacedeclarations).

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

{{table_1}}

<div class="alert-warning">NOTE: The text in this section is extracted from ETSI TS 103 410-10 (V2.1.1) <a href="#[0]">[0]</a>, and therefore falls inside the <a href="https://www.etsi.org/intellectual-property-rights">ETSI IPR Policy</a></div>

## Instantiating SAREF4WATR

This clause shows different examples of how to instantiate the SAREF4WATR extension of SAREF.

The example presented in [Figure 13](#Figure_13) depicts a water meter (ex:Meter4837QW123). It can be described by a set of static properties either reused from SAREF (e.g. [saref:hasModel](https://saref.etsi.org/core/hasModel)) or from SAREF4WATR (e.g. [s4watr:hasFirmwareVersion](#s4watr:hasFirmwareVersion)). The spatial extent of the meter is described by its geometry (ex:MeterGeom) that is represented as a point in space following its WKT representation. SAREF4WATR defines different measurable properties of a water meter, among them the battery remaining time ([s4watr:BatteryRemainingTime](#s4watr:BatteryRemainingTime)) that is the one used in the example. Observations of the meter for this property can be represented (ex:WMObservation200206) using for example the time instant of the observation and its value and the unit of measure in a property value.

The example presented in Figure 13 depicts a water meter (`ex:Meter4837QW123`). It can be described by a set of static properties either reused from SAREF (e.g. `saref:hasModel`) or from SAREF4WATR (e.g. `s4watr:hasFirmwareVersion`). The spatial extent of the meter is described by its geometry (`ex:MeterGeom`) that is represented as a point in space following its WKT representation. SAREF4WATR defines different measurable properties of a water meter, among them the battery remaining time (`s4watr:BatteryRemainingTime`) that is the one used in the example. Observations of the meter for this property can be represented (`ex:WMObservation200206`) using for example the time instant of the observation and its value and the unit of measure in a property value.

<figure>

  <img src="diagrams/SAREF4WATR Example water meter.png" alt="Example of water meter"/>

  <figcaption id="Figure_13">Figure 13: Example of water meter</figcaption>

    <img data-docx-width="16.65cm" src="diagrams/SAREF4WATR Example water meter.png" alt="Example of water meter"/>

    <figcaption>Figure 13: Example of water meter</figcaption>

</figure>

The main function of water meters is to measure water flow. [Figure 14](#Figure_14) presents two examples of water flow observations (ex:WFObservation170206 and ex:WFObservation643234) for a water flow property ([s4watr:FlowVolume](#s4watr:FlowVolume)) and an environmental one ([s4watr:ExternalTemperature](#s4watr:ExternalTemperature)), respectively. Notice how the flow volume observation is described with a time instant while the external temperature one is described with a time interval (ex:PT838452).

The main function of water meters is to measure water flow. Figure 14 presents two examples of water flow observations (`ex:WFObservation170206` and `ex:WFObservation643234`) for a water flow property (`s4watr:FlowVolume`) and an environmental one (`s4watr:ExternalTemperature`), respectively. Notice how the flow volume observation is described with a time instant while the external temperature one is described with a time interval (`ex:PT838452`).

<figure>

  <img src="diagrams/SAREF4WATR Example meter measurements.png" alt="Example of water meter observations"/>

  <figcaption id="Figure_14">Figure 14: Example of water meter observations</figcaption>

    <img data-docx-width="16.85cm" src="diagrams/SAREF4WATR Example meter measurements.png" alt="Example of water meter observations"/>

    <figcaption>Figure 14: Example of water meter observations</figcaption>

</figure>

Different tariffs can be applied to water meters. [Figure 15](#Figure_15) presents an example of a consumption-based tariff (ex:Meter4837QW123Tariff) for a water meter (ex:Meter4837QW123). Different individuals are defined for describing the duration (ex:FiveYears), period (ex:OneYear) and billing period (ex:OneMonth) of the tariff. SAREF4WATR does not restrict how to define particular conditions of a tariff; in the example, for the consumption description a string literal is used.

Different tariffs can be applied to water meters. Figure 15 presents an example of a consumption-based tariff (`ex:Meter4837QW123Tariff`) for a water meter (`ex:Meter4837QW123`). Different individuals are defined for describing the duration (`ex:FiveYears`), period (`ex:OneYear`) and billing period (`ex:OneMonth`) of the tariff. SAREF4WATR does not restrict how to define particular conditions of a tariff; in the example, for the consumption description a string literal is used.

<figure>

  <img src="diagrams/SAREF4WATR Example tariff.png" alt="Example of tariff"/>

  <figcaption id="Figure_15">Figure 15: Example of tariff</figcaption>

    <img data-docx-width="16.39cm" src="diagrams/SAREF4WATR Example tariff.png" alt="Example of tariff"/>

    <figcaption>Figure 15: Example of tariff</figcaption>

</figure>

The observation of the different properties of the water itself is also of interest. [Figure 16](#Figure_16) presents two observations (ex:DTSObservation106 and ex:DTSObservation107) of one chemical property ([s4watr:Cadmium](#s4watr:Cadmium)) and of one bacterial property ([s4watr:EscherichiaColi](#s4watr:EscherichiaColi)), along with their timestamps, values and units. Even if SAREF4WATR includes a set of predefined water properties, other properties could be defined by instantiating the corresponding [s4watr:WaterProperty](#s4watr:WaterProperty) subclass.

The observation of the different properties of the water itself is also of interest. Figure 16 presents two observations (`ex:DTSObservation106` and `ex:DTSObservation107`) of one chemical property (`s4watr:Cadmium`) and of one bacterial property (`s4watr:EscherichiaColi`), along with their timestamps, values and units. Even if SAREF4WATR includes a set of predefined water properties, other properties could be defined by instantiating the corresponding `s4watr:WaterProperty` subclass.

<figure>

  <img src="diagrams/SAREF4WATR Example water measurements.png" alt="Example of water observations"/>

  <figcaption id="Figure_16">Figure 16: Example of water observations</figcaption>

    <img data-docx-width="16.99cm" src="diagrams/SAREF4WATR Example water measurements.png" alt="Example of water observations"/>

    <figcaption>Figure 16: Example of water observations</figcaption>

</figure>

[Figure 17](#Figure_17) depicts a water infrastructure (ex:DowntownDS) that represents a distribution system for drinking water ([s4watr:DrinkingWater](#s4watr:DrinkingWater)) intended for domestic use ([s4watr:Domestic](#s4watr:Domestic)). The spatial extent of the infrastructure is described by its geometry (ex:DSGeom) that is represented as a polygon in space following its WKT representation. The water distribution system has different subsystems: a water meter (ex:Meter4837QW123), a tank (ex:Tank38472) and a pump (ex:PumpRT73467). These subsystems can be represented through their geometries, as points in the example (ex:MeterGeom, ex:TankGeom, ex:PumpGeom), and different measures could be made of them such as the one depicted (ex:PObservation854306) that observes the flow rate ([s4watr:FlowRate](#s4watr:FlowRate)) of the pump.

Figure 17 depicts a water infrastructure (`ex:DowntownDS`) that represents a distribution system for drinking water (`s4watr:DrinkingWater`) intended for domestic use (`s4watr:Domestic`). The spatial extent of the infrastructure is described by its geometry (`ex:DSGeom`) that is represented as a polygon in space following its WKT representation. The water distribution system has different subsystems: a water meter (`ex:Meter4837QW123`), a tank (`ex:Tank38472`) and a pump (`ex:PumpRT73467`). These subsystems can be represented through their geometries, as points in the example (`ex:MeterGeom`, `ex:TankGeom`, `ex:PumpGeom`), and different measures could be made of them such as the one depicted (`ex:PObservation854306`) that observes the flow rate (`s4watr:FlowRate`) of the pump.

<figure>

  <img src="diagrams/SAREF4WATR Example water infrastructure.png" alt="Example of water infrastructure and water assets"/>

  <figcaption id="Figure_17">Figure 17: Example of water infrastructure and water assets</figcaption>

    <img data-docx-width="16.83cm" src="diagrams/SAREF4WATR Example water infrastructure.png" alt="Example of water infrastructure and water assets"/>

    <figcaption>Figure 17: Example of water infrastructure and water assets</figcaption>

</figure>

[Figure 18](#Figure_18) contains an example of a key performance indicator (ex:MinimumPressureLevel) defined for a water distribution system (ex:DowntownDS). The key performance indicator is defined with its name and calculation period (ex:OneWeek). Besides, an assessment is made for the KPI (ex:MPL2020020723), derived from existing observations (ex:PLObservation56206, ex:PLObservation56207 and ex:PLObservation56208), indicating the value of the assessment and its temporal properties.

Figure 18 contains an example of a key performance indicator (`ex:MinimumPressureLevel`) defined for a water distribution system (`ex:DowntownDS`). The key performance indicator is defined with its name and calculation period (`ex:OneWeek`). Besides, an assessment is made for the KPI (`ex:MPL2020020723`), derived from existing observations (`ex:PLObservation56206`, `ex:PLObservation56207` and `ex:PLObservation56208`), indicating the value of the assessment and its temporal properties.

<figure>

  <img src="diagrams/SAREF4WATR Example KPI.png" alt="Example of key performance indicator"/>

  <figcaption id="Figure_18">Figure 18: Example of key performance indicator</figcaption>

    <img data-docx-width="16.96cm" src="diagrams/SAREF4WATR Example KPI.png" alt="Example of key performance indicator"/>

    <figcaption>Figure 18: Example of key performance indicator</figcaption>

</figure>

## Discussion

In the following paragraphs, several observations about the SAREF4WATER ontology and its usage are mentioned. 

The hierarchies and individuals defined in the extension should not be considered exhaustive, the ontology currently represents those devices described in different relevant standards and directives. It might be needed to extend the hierarchies and lists of individuals for particular use cases, as well as to specialize some of the defined classes.

Apart from this, some of the properties defined for a water meter that were extracted from the M-Bus standard are quite generic (e.g. `s4watr:hasHardwareVersion` or `s4watr:hasFirmwareVersion`) and could be applicable to other domains (at least those covered by the standard: energy and gas). Therefore, they could also be moved to SAREF.