Time series flags describe the origin and the quality of the data.

Possible origins of data are:

-       Original: This entails the data value is the original value. It has not been amended by Delft-FEWS

-       Completed: This entails the original value was missing and was replaced by a non-missing value.

-       Corrected: This entails the original value was replaced with another non-missing value.

Possible Qualities are:

-       Reliable: Data is reliable and valid

-       Doubtful: The validity of the data value is uncertain

-       Unreliable: The data value is unreliable and cannot be used for calculations like transformations or external models. It can still be viewed and exported with a regular exportModule as long as the unreliable flag is shown with it.

Following this specification, the table below gives an overview of quality flag enumerations

Table D.1               Enumeration of quality flags

Enumeration

Description

0

Original/Reliable
The data value is the original value retrieved from an external source and it successfully passes all validation criteria set.

1

Corrected/Reliable
The original value was removed and corrected. Correction may be through interpolation or manual editing.

2

Completed/Reliable
Original value was missing. Value has been filled in through interpolation, transformation (e.g. stage discharge) or a model.

3

Original/Doubtful
Observed value retrieved from external data source. Value is valid, but marked as suspect due to soft validation limits being exceeded.

4

Corrected/Doubtful
The original value was removed and corrected. However, the corrected value is doubtful due to validation limits.

5

Completed/Doubtful
Original value was missing. Value has been filled in as above, but resulting value is doubtful due to limits in transformation/interpolation or input value used for transformation being doubtful.

6

Missing/Unreliable
Observed value retrieved from external data source. Value is invalid due to validation limits set. Value is removed

7

Corrected/Unreliable
The original value was removed and corrected. However, corrected value is unreliable and is removed.

8

Completed/Unreliable
Original value was missing. Value has been filled in as above, but resulting value is unreliable and is removed.

9

Missing value in originally observed series. Note this is a special form of  Original/Unreliable. Missing values are automatically unreliable

10

Deleted

Only used for non-equidistant series when timestep is deleted

11, 12, 13

Not used

14

Reset

Used for rainfall data processing when the storage is reset (canister reset)


Next to the flag it is also possible to get or set information why the flag is as it is through the so-called flagSource. Since version 2012.01 FEWS stores not only the quality flags, but also the source of the flag, the so-called flagSource. So the user is able to see why a certain value is validated as unreliable, eg. due to exceeding of the hard max.
The list of flagSources is:

  • IMP: flag is imported
  • SN: soft min.
  • HN: hard min.
  • SX: soft max.
  • HX: hard max.
  • ROR: rate of rise
  • ROF: rate of fall
  • SR: same reading
  • TS: temporary shift
  • OSC: oscillation
  • SC: secondary validation, series comparison
  • FC: secondary validation, flag comparison
  • MK: secondary validation, Mann-Kendall test
  • SVP: secondary valdidation, Flag persistency (FlagPersistencyCheck)
  • SFP: start flag persistency 
  • MAN: manual edit
  • MK: mann kendall
  • CA: Conditional aggregation


  • No difference is made between historic and forecast data. This is not considered a quality flag. The data model of NFFS is constructed such that this difference is inherent to the data type definition.
  • External sources may either be an actual external source, a forecasting module or a transformation. The convention in NFFS the definition of data series parameter types identifies the data source.
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