Table 1.
Correlations between the extracted water quality parameters for the different sampled stations/reaches during end-March to early-April 2020.
| Parameters | NDTI | NDVI | FAI | SPM | T_Nch2016 | T_Dog2015 | pH | BOD | DO | COD | FC |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NDTI | 1 | ||||||||||
| NDVI | 0.37 | 1 | |||||||||
| FAI | 0.15 | 0.95⁎⁎ | 1 | ||||||||
| SPM | 0.76⁎ | 0.31 | 0.19 | 1 | |||||||
| T_Nch2016 | 0.76⁎ | 0.31 | 0.19 | 1⁎⁎ | 1 | ||||||
| T_Dog2015 | 0.86⁎⁎ | 0.40 | 0.26 | 0.86⁎⁎ | 0.86⁎⁎ | 1 | |||||
| pH | 0.21 | −0.02 | −0.16 | 0.41 | 0.41 | 0.44 | 1 | ||||
| BOD | −0.13 | 0.27 | 0.40 | −0.28 | −0.28 | −0.37 | −0.94⁎⁎ | 1 | |||
| DO | 0.05 | −0.35 | −0.41 | 0.37 | 0.37 | 0.38 | 0.87⁎⁎ | −0.93⁎⁎ | 1 | ||
| COD | 0.19 | 0.20 | 0.27 | 0.10 | 0.10 | −0.05 | −0.85⁎⁎ | 0.87⁎⁎ | −0.75⁎ | 1 | |
| FC | −0.30 | 0.45 | 0.62 | −0.13 | −0.13 | −0.22 | −0.19 | 0.42 | −0.27 | 0.18 | 1 |
Source: Computed by the authors.
Only those nine reaches were considered in the above correlation, within which were located the water sample measurement stations. There is a slight dissonance between the dates of the satellite-image derived parameters and the measured water sample dates. The former is from the 29.03.2020 dataset while the latter is from the 06.04.2020 dataset. T_Nch2016 and T_Dog2015 respectively denote the turbidity values obtained via the Nechad (2009, re-updated in 2016) and Dogliotti et al. (2015) methods.
Correlation is significant at the 0.05 level (2-tailed).
Correlation is significant at the 0.01 level (2-tailed).