## 3 Results
### Spatial Variation of Water Quality  
The dissolved oxygen levels measured during the field campaign vary between 5.8 and 9.7 mg/L, while the values estimated by the model show a minimum value of 6.39 mg/L and a maximum one of 9.39 mg/L (Figure 6). The spatial variation of this parameter shows a well-oxygenated zone in the northeast of the reservoir. This area represents the water inlet to the reservoir. For the spatiotemporal variation, the maps of different months show high values in the northeastern part of the reservoir with a decrease moving away from this area (Figure 6). Except for few months such as January, October and December, this variation can be explained by the coincidence of these periods with that of water \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **B1** & **B2** & **B3** & **B4** & **B5** & **B6** & **B8** \\ \hline
**Chl-a** & - & - & - & - & 0.81 & 0.71 & 0.73 \\
**Nitrates** & 0.73 & - & 0.69 & 0.73 & - & - & - \\
**Dissolved Oxygen** & - & 0.71 & 0.75 & - & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Correlation between satellite bands and water quality parameters. Figure 5: Water quality parameters measured versus estimated through the models (best models’ performance). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Model Equations**} & \multicolumn{2}{c}{**RMSE**} & \multicolumn{1}{c}{**R2**} & \multicolumn{1}{c}{\(p\)**-Value**} \\ \hline  & & 0.00372 \(\times\)**B01 \(-\)**3.05 & 0.19 (mg/L) & 0.39 & 0.0030 \\  & & 0.00895 \(\times\)**B03 + 0.31 & 0.24 (mg/L) & 0.06 & 0.2945 \\  & & 0.00114 \(\times\)**B04 + 0.630 & 0.19 (mg/L) & 0.39 & 0.0031 \\ Nitrate & 0.00372 \(\times\)**B01 \(-\)**(3.056 \(\times\) 10\({}^{-7}\)) \(\times\)**B03 \(-\)**3.0593 & 0.20 (mg/L) & 0.39 & 0.0140 \\  & 0.00273 \(\times\)**B01 \(+\)**0.0004 \(\times\)**B04 \(-\)**2.53264 & 0.17 (mg/L) & 0.58 & 0.0067 \\  & 0.000412 \(\times\)**B03 \(+\)**0.00125 \(\times\)**B04 \(+\)**1.1273 & 0.20 (mg/L) & 0.40 & 0.0127 \\  & **0.003099 \(\times\)**B01 \(-\)**0.000944 \(\times\)**B03 +**0.0010509 \(\times\)**B04 \(-\)**1.81** & **0.16(mg/L)** & **0.62** & **0.0011** \\ \hline Dissolved Oxygen & & 0.0128 \(\times\)**B02 - 8.324 & 0.75 (mg/L) & 0.30 & 0.0040 \\  & 0.0102 \(\times\)**B03 - 6.704 & 0.63 (mg/L) & 0.55 & 0.0001 \\  & **0.00075 \(\times\)**B02 + 0.00989 \(\times\)**B03 \(-\)**7.09** & **0.65(mg/L)** & **0.56** & **0.0009** \\ \hline  & & 0.0007071 \(\times\)**B05 + 0.184 & 0.07 (mg/L) & 0.41 & 0.0022 \\  & 0.0010213 \(\times\)**B06 + 0.3066 & 0.08 (mg/L) & 0.37 & 0.0042 \\  & 0.002332 \(\times\)**B08 \(-\)**0.15655 & 0.07 (mg/L) & 0.45 & 0.0011 \\ Chl-a & 0.0004766 \(\times\)**B05 + 0.000591 \(\times\)**B06 + 0.144903 & 0.07 (mg/L) & 0.49 & 0.0029 \\  & 0.000423 \(\times\)**B05 + 0.001572 \(\times\)**B08 \(-\)**0.1589 & 0.07 (mg/L) & 0.55 & 0.0010 \\  & 0.000574 \(\times\)**B06 + 0.00167 \(\times\)**B08 \(-\)**0.1076 & 0.07 (mg/L) & 0.53 & 0.0015 \\  & **0.0003214 \(\times\)**B05 + 0.000378 \(\times\)**B06 + 0.0013207 \(\times\)**B08 \(-\)**0.126** & **0.07(mg/L)** & **0.58** & **0.0024** \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Statistical parameters of the best performance models. supply for agriculture downstream of the dam which allows the movement of water in the reservoir and consequently an agitation of the water leading to an increase in the values of this parameter. Generally, the samples showed an excellent quality from the point of view of the nitrate parameter with values ranging between 0.8 and 1.96 mg/L. The estimated values for the model are between 1.11 and 1.96 mg/L (Figure 7). The spatial variation of nitrate shows a decrease in values from the northeastern part of the reservoir, representing the outlet, to the southeastern part (Figure 7). The temporal variation shows that nitrate values do not exceed 10 mg/L throughout the year. This proves the excellent water quality of this reservoir.