Traitement et analyse de séries chronologiques continues de ...

Annexes
Table 1. Pre-validation parameters for Tests 2, 3 and 5
Test 2 Test 3 Test 5 (median)
WWF DWF WWF DWF
Parameters Min Max Min Max Min Max Min Max Min Max
Conductivity
(µS cm -1 ) 0 2500 10 2000 300 2000 0.01 100 0.01 50
Water level
(m)
pH (pH unit)
0 2 0.05 0.9 0.001 0.2 0.001 0.003 0.001 0.015
0 14 3 12 3 12 10e-6 0.25 10e-6 0.25
Temperature
(° C)
0 100 2 30 2 30 10e-6 0.3 10e-6 0.3
Turbidity
(NTU)
0 4000 5 2000 5 500 0.01 50 0.01 50
Note: WWF =wet weather flow; DWF = dry weather flow
Examples of results are given in Figure 2. The data validation graphical user interface is shown in
Figure 2a for a 20 day period in January 2008. Colours indicate the various marks given by the
automatic pre-validation algorithms. Some doubtful and non valid data appear for both the water level
(two abnormal short peaks on 9 and 11 January 2008) and turbidity (incorrect negative values and
constant zeros values appearing in red). In the future, new functions will be added to fill gaps in time
series by applying algorithms which are currently under evaluation for gaps ranging from a few
minutes to periods as long as one day or more.
Figures 2b and 2c shows respectively the Turbidity-TSS (left figure) and Turbidity-COD (right figure)
correlation functions for wet weather conditions. Both are second order polynomial functions
determined by means of Williamson regression to account for uncertainties in both variables (turbidity
and TSS or COD). Grey areas correspond to 95 % confidence intervals in estimated TSS or COD
concentrations. It is important to note that both functions have been established with samples collected
during various storm events covering a large measurement range (respectively 0 - 680 NTU
corresponding to 0 - 1000 mg/L of TSS and 0 - 800 NTU corresponding to 0 - 800 mg/L of COD).
This is important to ensure that the correlation functions are applicable for various conditions and
without undue extrapolation.