OGC WaterML 2.0 OGC 10-126r4
Copyright © 2012-2014 Open Geospatial Consortium 65
Defining groups of sampling points is often required, allowing multiple sampling points to be associated with a particular identifier or name. This is common in hydrology as organisations
often have a number of sampling points often closely located that may be named for the purposes of site visits, maintenance or reporting. A SamplingFeatureCollection is how a group
such as a “field site with many sampling locations” would be expressed.
Figure 32 - SF_SamplingFeatureCollection as defined by ISO19156
A sampling group may be defined by fully defining each of the sampling features contained in the group, or by referencing each of the sampling points in the group.
It is possible to implement sampling groups in both directions: When defining the sampling point, include a relation to the sampling features in the group
using the relatedSamplingFeature property. Define a SF_SamplingFeatureCollection that contains the sampling points. Note: this can
be done by referencing already defined sampling points through an identifier or by defining the containing points directly inline.
The two approaches are useful in different scenarios; guidance on their use is expanded in examples and future best practice guides.
9.22 Requirements class: Observation process Requirements Class
http:www.opengis.netspecwaterml2.0requml-observation-process Target Type
Encoding of the conceptual model
Name Observation process
Dependency
urn:iso:dis:iso:19156:clause:9
I eature
«FeatureType»
m i
t e
«FeatureType»
SF_SamplingFeatureCollection
Collection +member
1..
Copyright © 2012-2014 Open Geospatial Consortium 66
Requirement
requml-observation-processvalid
The om:procedure property shall point to a feature type that represents the ObservationProcess class described in
Figure 33
with attributes and associations.
Requirement
requml-observation-processprocessType
The processType property of ObservationProcess shall use the appropriate type from
Table 8
. Within OM, the ProcessUsed association links the observation to the OM_Process used to
generate the result. OM_Process is abstract and does not define any attributes or associations. This standard specialises OM to define process specific to hydrology, as shown in Figure 33.
Figure 33 - Observation process feature type
A large number of direct in-situ hydrological observations are performed by a sensor or sensor system. Common types of sensors include rain gauges, water level gauges, water quality sensors
such as temperature, turbidity etc.
Manual procedures may also be used to make measurements at a particular sampling point. These may be ad-hoc visits to a particular point, or continued visits to a well identified sampling point.
Procedures that generate derived or synthetic results also exist, such as those produced by algorithms or simulations. Algorithms are commonly implemented in hydrological software to
process data sets for reporting or other purposes. Examples include:
Temporal interpolation or aggregation; Spatial interpolation;
«FeatureType»
Observ ationProcess
+ aggregationPeriod :TM_PeriodDuration [0..1] + gaugeDatum :CD_VerticalDatum [0..1]
+ input :GenericName [0..] + operatorComments :CharacterString [0..]
+ parameter :NamedValue [0..] + processReference :GenericName [0..1]
+ processType :ProcessTypeCode «CodeList»
ProcessTypeCode
«datatype»
Citation and responsible party information:: CI_ResponsibleParty
+ individualName :CharacterString [0..1] + organisationName :CharacterString [0..1]
+ positionName :CharacterString [0..1] + contactInfo :CI_Contact [0..1]
+ role :CI_RoleCode «FeatureType»
observati :
OM_Process
+originatingProcess 0..1
+operator 0..1
