WaterWare Release Notes
    Release Level 5.0
    Release Date 2005 06
    Revision Level 1.0

Monitoring stations and time series data

A central class in WaterWare are the monitoring stations and their associated time series of observation data: meteorological variables, river flow or levels, water quality, reservoir and groundwater levels, release and pumping rates.

The primary selector shows the monitoring stations. With every monitoring station, the basic meta data attributes such as name, owner, and last modification dates (most relevant for real-time data acquisition stations) are shown.

A monitoring station object is defined by its name, meta data including owner/user, creation and last modification dates, a hypertext link to descriptive multi-media data.

The station location is shown on a map of the stations surroundings.

The primary attributes of a monitoring stations are the time series of monitoring data, These are shown in a selector at the bottom of the page, where time series data files can be sorted by parameter, temporal coverage, and number of observations, and last update, important for real-time data acquisition cases.
The map display of the station location and surroundings can be interactively configured by the user, subject to his write privileges i.e., ownership of the object data.

The position of the station can be set interactively on the map by just clicking on the desired location, or alternatively, by directly specifying the locations coordinates.

The zooming factor of the local map is defined by specifying the radius to be shown around the station location, with the station always centered in the map window shown.
The monitoring data time series is shown

  • in a tabular summary of the overall statistics;
  • in a compressed overview of the entire observation period;
  • for the last, most recent period.
The period shown and the aggregation of the data depend on the original temporal resolution or time step, and the temporal coverage of the available data.
For the analysis of a time series, a number of specific functions are available. They include, in addition to basic descriptive statistics:
  • histogram of a single data set's distribution
  • direct comparison of two stations or two parameters
  • correlation of two synchronized data sets
  • compliance with a standard
  • outlier detection (data quality assurance).

The direct comparison option shows two user selected data sets, synchronized, together.

The user can select the second data set from the list of available stations and variables that have data overlapping in time that can be synchronized. The display includes:

  • table of descriptive statistics (statistical moments of the distributions)
  • display of the two time series data on top of each other.

The correlation analysis includes, in addition to the statistical analysis as above,
  • scattergram, plotting the two data sets against each other, and the corresponding linear correlation coefficient;
  • histograms for the two data sets.

The compliance analysis determines the number of observations that exceed a user specified threshold value.

The analysis indicated the number of exceedances, as well as the AOT (average above threshold) value.
The outlier detection attempts to find erroneous values in an observation data set. Several test can be performed individually or together. They include:

  • bounds checks whether value are within a user defined interval;
  • absolute delta: puts an absolute limit on increase or decrease from one value to the next;
  • relative delta: same as above, but in relative terms;
  • duplicates: finds neighboring values that are exactly the same, sometimes suggesting a data entry error.

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