Parameters
The parameter is a three-character specification of the type of data. Any combination of three characters is permitted and can be added to the available set.
Examples
PH = historical precipitation
PG = generated precipitation
H1 = water levels upstream of structure
H2 = water levels downstream of structure
QH = historical discharge
To each data type belongs a data unit and a type of observation, (e.g. accumulative or instantaneous).
With the function 'Parameters' you can add, delete and edit parameters.
Units
The data unit is a characteristic of the data type. For a specific data type one and only one unit applies. Any unit can be used for the data in HYMOS; however, the use of SI-units is strongly recommended.
Type of observation
The type of observation is another characteristic of the data type, and it refers to the sampling or computational procedure used to obtain the data. Following types of observations are distinguished for equidistant time series:
- instantaneous observations:
- Equidistant time series: The observation is made at a certain point in time within the time interval Dt; it produces one instantaneous exposure of the process in a time span Dt, like e.g. water level time series, discharge time series.
- Non-equidistant time series: The observation is made at a certain point in time. It produces one instantaneous exposure of the process, e.g. a groundwater level observation. In between two observations the value of the process is uncertain.
- accumulative observations:
- Equidistant time series: The observation is the integral of the continuous process in the time interval t, t + Δt, like for example rainfall amounts. Accumulative observations produce volumes rather than intensities. For example, runoff expressed in mm is accumulative, whereas runoff expressed in m3/s is instantaneous
- Non-equidistant time series: accumulative observations are not valid.
- average observations:
- Equidistant time series: computed quantities, obtained e.g. by aggregation of instantaneous observations over a larger time interval. Average observations are treated in hymosas instantaneous observations since in common mathematical operations they are equivalent. (From a view-point of information content they are, however, different: by averaging, information about the process is lost!)
- Non-equidistant time series: average observations are not valid, and
- constants:
- Equidistant time series: constants are not useful,
- Non-equidistant time series: The process remains constant from one observation until the next. This is typically representative for time series with human interference, like e.g. gate levels fixed for a period of time or pumps in operation.
The type of observation has important consequences for aggregation of time series (i.e. averaging versus summing) as well as for dis-aggregation of time series.
In this parameter form you can make a selection between 'instantaneous' and 'accumulative' parameters.
Press <Add New> to add a new parameter, <Save> to save the entered or edited information in the database, <Delete> to delete a parameter from the database, <Close> to leave the window without saving.
