20 Transformation Module (Improved schema)

Transformation Module Configuration (New Version)

The Transformation module is a general-purpose module that allows for generic transformation and manipulation of time series data. The module may be configured to provide for simple arithmetic manipulation, time interval transformation, shifting the series in time etc, as well as for applying specific hydro-meteorological transformations such as stage discharge relationships etc.

An improvement version of the FEWS Transformation Module is currently under construction. The new version is much more easy to configure than the old version. The new version uses a new schema for configuration, also several new transformations are added.

Configuration    

When available as configuration on the file system, the name of an XML file for configuring an instance of the transformation module called for example TransformHBV_Inputs may be:

TransformHBV_Inputs 1.00 default.xml.

The configuration for the transformation module consists of two parts: transformation configuration files in the Config/ModuleConfigFiles directory and coefficient set configuration files in the Config/CoefficientSetsFiles directory.

In a transformation configuration file one or more transformations can be configured. Some transformations require coefficient sets in which given coefficients are defined. For a given transformation that requires a coefficient set there are different ways of defining the coefficient set in the configuration. One way is to specify an embedded coefficient set in the transformation configuration itself. Another way is to put a reference in the transformation configuration. This reference consists of the name of a separate coefficient set configuration file and the id of a coefficient set in that file.

Both the transformations and coefficient sets can be configured to be time dependent. This can be used for instance to define a given coefficient value to be 3 from 1 January 2008 to 1 January 2009, and to be 4 from 1 January 2009 onwards. This can be done by defining multiple periodCoefficientSets, each one with a different period, as in the following xml example.

<periodCoefficientSet>
  <period>
    <startDateTime date="2008-01-01" time="00:00:00"/>
    <endDateTime date="2009-01-01" time="00:00:00"/>
  </period>
  <structure>
    <pumpFixedDischarge>
      <discharge>3</discharge>
    </pumpFixedDischarge>
  </structure>
</periodCoefficientSet>
<periodCoefficientSet>
  <period>
    <validAfterDateTime date="2009-01-01"/>
  </period>
  <structure>
    <pumpFixedDischarge>
      <discharge>4</discharge>
    </pumpFixedDischarge>
  </structure>
</periodCoefficientSet>

If a date is specified without a time, then the time is assumed to be 00:00:00, so <validAfterDateTime date="2009-01-01"/> is the same as <validAfterDateTime date="2009-01-01" time="00:00:00"/>. To specify dates and times in a particular time zone use the optional time zone element at the beginning of a transformations or a coefficient sets configuration file, e.g. <timeZone>GMT+5:00</timeZone>. Then all dates and times in that configuration file are in the defined time zone. If no time zone is defined, then dates and times are in GMT. Note: 2008-06-20 11:33:00 in time zone GMT+5:00 is physically the same time as 2008-06-20 06:33:00 in GMT.

If for a given transformation there are different coefficientSets configured for different periods in time, then the following rule is used. The start of a period is always inclusive. The end of a period is exclusive if another period follows without a gap in between, otherwise the end of the period is inclusive. If for example there are three periodCoefficientSets defined (A, B and C), each with a different period, as in the following xml example. Then at 2002-01-01 00:00:00 periodCoefficientSet A is valid. At 2003-01-01 00:00:00 periodCoefficientSet B is valid since the start of the period is inclusive. At 2004-01-01 00:00:00 periodCoefficientSet B is still valid, since there is a gap after 2004-01-01 00:00:00. At 2011-01-01 00:00:00 periodCoefficientSet C is valid, since no other periods follow (the period of C is the last period in time that is defined). This same rule applies to time-dependent transformations.

<periodCoefficientSet>
  <!-- periodCoefficientSet A -->
  <period>
    <startDateTime date="2002-01-01" time="00:00:00"/>
    <endDateTime date="2003-01-01" time="00:00:00"/>
  </period>
  ...
</periodCoefficientSet>
<periodCoefficientSet>
  <!-- periodCoefficientSet B -->
  <period>
    <startDateTime date="2003-01-01" time="00:00:00"/>
    <endDateTime date="2004-01-01" time="00:00:00"/>
  </period>
  ...
</periodCoefficientSet>
<periodCoefficientSet>
  <!-- periodCoefficientSet C -->
  <period>
    <startDateTime date="2010-01-01" time="00:00:00"/>
    <endDateTime date="2011-01-01" time="00:00:00"/>
  </period>
  ...
</periodCoefficientSet>