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Rating Curves Configuration

 The transformation stageDischarge/ratingCurve uses rating curves according to the schema pi-ratingcurves.xsd. It is possible to store the ratingcurves in a ratingCurves.xml file in the regionConfig directory. However it is recommended to store 

the ratingCurves to the FEWS database. The ratingCurves can be imported in the FEWS database by using a dedicated import which is capable of importing rating curves from file as long as the file is compliant with the pi-ratingCurves.xsd schema.

Rating Curve schema

Below an overview of the schema of the pi-ratingcurves.

Header

The header element contains the metadata about the rating curve. Below an overview of the available elements.

locationId

The location id for which the rating curve is valid

qualifierId

The allows the configurator to add 1 or more qualifier to the definition of the rating curve. This is useful when for 1 location more rating curves are valid.

The locationId and the configured qualifiers define the id of the rating curve.

startDate

This element defines when the rating curve becomes active.

endDate

This (optional) element defines until when the rating curve is active.

longName

Optional descriptive name

stationName

Optional station name

stageUnit

Definition of the stage unit

dischargeUnit

Definition of the discharge unit

comment

This section allows to define a (optional comment) for the rating curve. If a comment is defined the comment will be shown in the TimeSeriesDialog when viewing the rating curve.

creationDate

The date on which the rating curve was created.

creationTime

The time on which the rating curve was created.

region

The description of the region. This is needed when the id of the rating curve is the same in different regions.

Table

The table contains the actual description of the rating curve.

InterpolationMethod

Two options are available:linear and logaritmic. When linear is selected the calculation is done by the regular linear method.

The slope will be computed as:

THe discharge can be calcuted from the stage by using the following equation:

When the logartimic option is selected the slope will be calculated by:

The discharge can be computed by using the following equation:

The stage can be computed by using the following equation:

When an offset is defined the stage can be calculated by:

minStage

The minimum stage which is allowed for this rating curve. If the minStage is configured as 0.2m and a stage of 0.1m is used as input to calculate a discharge.

than the actual stage used in the calculation will not 0.1m but 0.2m. If the rating curve is used in a discharge to stage calculation and the calculated stage is lower than

the minStage than the calculated stage will be set to the minStage value. If, for example, the minStage is set 0.2m and the calculated stage is equal to 0.1m the

actual calculated stage will be corrected to 0.2m to ensure that no stages lower than minStage are calculated.

This option is usually used to limit the stage value calculated when using extrapolation.

maxStage

The maximum stage which is allowed for this rating curve. 

If the maxStage is configured as 5.2m and a stage of 5.5m is used as input to calculate a discharge,

then the actual stage used in the calculation will not be 5.5m but 5.2m. If the rating curve is used in a discharge to stage calculation and the calculated stage is higher than

the maxStage than the calculated stage will be set to the maxStage value. If, for example, the maxStage is set 5.2m and the calculated stage is equal to 5.5m the

actual calculated stage will be corrected to 5.2m to ensure that no stages higher than maxStage are calculated.

row

The row element can be used to define the rows of the stage-discharge table. Each row has a mandatory stage and discharge element. An optional offset can be added.

If a row doesn't include an offset element then the previous defined offset will be used.