Traitement et analyse de séries chronologiques continues de ...

Annexes
type and number of sensors (see Figure 1). The following paragraphs briefly describe the parametric
tests with an indication of the required parameters.
Test 1a checks if data have been recorded or not. No parameter is required for this test. Test 1b checks
if data have been recorded during a maintenance operation by comparing their dates with dates of
maintenance provided in a specific file entered by the operator in charge of the maintenance.
Test 2 detects any data outside the sensor measurement range. Its two parameters are the minimum and
maximum measurable values.
Test 3 checks if recorded data are within the interval defined by two parameters corresponding to the
2.5 percentile and 97.5 percentile of previously validated values measured with a given sensor in a
given location. The two parameters may change with time when more values are observed under
various dry and wet weather conditions.
Test 4 requires two parameters which compare measurement dates to the last maintenance date and
classifies data as either correct, doubtful or even non valid if the duration elapsed since the last
maintenance is too long.
Test 5 detects sudden, abnormal or erratic increases or decreases of values by comparing the
difference between instantaneous values (raw signal) and the mobile mean or median (filtered signal).
The required parameters are the number of time steps for the mobile mean or median calculation and
minimum and maximum threshold values.
Test 6 compares the values and the signal dynamics of two redundant sensors in order to detect
unusual trends or abnormal gaps.
Test 7 is similar to Test 6 in its principle but compares values and the signal dynamics of any
correlated variables (e.g. water level and flow velocity, upstream and downstream values, measured
and simulated discharges, etc.).
Test 8 qualifies data for a given sensor (the influenced sensor) depending on values delivered by
another sensor. The test requires threshold values for the influencing sensors and classifies the data of
the influenced sensor as either correct or doubtful. For example, in the case of water level and velocity
sensors, if the water level is too low, velocity measurements are considered as doubtful. As for Test 3,
influenced and influencing sensors and threshold values are based on previous validated data and may
change with time and experience of the operator.
Data pre-validation
Pre-validation tests are applied to corrected data in order to assign validation marks. It should be noted
that all tests are not applicable to all data series. Only Tests 1a to 5 can be applied to all sensors. Tests
2, 3 and 5 are sensor specific. Tests 6, 7 and 8 can only be applied if redundant or correlated
information is available. For Tests 2, 3 and 5, specific threshold values can be specified for both dry
and wet weather conditions. The distinction between the two conditions is defined by the operator and
can be based on any sensor and corresponding threshold value or on any combination of values.
The pre-validation procedure is shown in Figure 1. For each value, Tests 1a and 1b are run first. If the
value is identified as not valid, its validation mark is set to 3 and the pre-validation procedure is