## 4 Initial Conditions and Numerical Results
### Numerical Results
#### 4.2.3 Model Validation  
As part of the validation of the model, the Grand-Cuaga basin has been used, which is located in Burkina Faso, West Africa (Figure 10). The watershed is located between parallels 12.26\({}^{\circ}\) and 12.35\({}^{\circ}\) North in latitude and between meridians 1.43\({}^{\circ}\) and 1.54\({}^{\circ}\) West in longitude. This study is based on data from the floods that occurred in the area from 18 to 22 July 2016 (case study 1) and 25 July 2017 (case study 2). Prior to the flood, a water level gauge that allows the recording and transmission of the measurement of water height at the given point in a watercourse had been installed at the outlet. This work involved simulating the water height at the outlet, located at longitude: \(-1^{\circ}26^{\prime}\) E and latitude: 12\({}^{\circ}\)18\({}^{\prime}\) N, and comparing it to the measured data collected in the field. The mapping of the area was made according to the steps mentioned in Section 3.1 (Description of the watershed) in the current paper. Table 3 presents the infiltration parameters provided by the Burkina Faso National Institute of Geography ([[http://www.igb.bf/](http://www.igb.bf/)]([http://www.igb.bf/](http://www.igb.bf/)) accessed on 18 January 2018). The rainfall data used in the case study were collected from project activities ([[https://www.amma2050.org/](https://www.amma2050.org/)]([https://www.amma2050.org/](https://www.amma2050.org/)) 18 to 22 July 2016; 25 July 2017). The results are presented in Figures 11a and 12a for case study 1 and case study 2, respectively, and the Manning coefficients were taken [49]. At the beginning of the long rains from 18 to 22 July 2016, the water height at the outlet was estimated to be 0.32 m, while on 25 July 2017, the water height was 0 m. The comparison made between the simulated water height and the measured height is illustrated in Figures 11b and 12b, for case 1 and case 2, respectively. The first comparison conducted for case study 1 (Figure 11a) over 24 h suggests a large difference in the maximum value between the observed data (2.21 m) and the simulated data (1.9 m). The Nash-Sutcliffe value is 0.7, which means a good correlation was observed between the two curves at the beginning and the end of the simulation. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Land Cover** & \(i_{t}\) & \(i_{o}\) & \(\mathbf{r\,(min^{-1})}\) \\ \hline Vegetated & 0.22 & 2.95 & 0.503 \\ Bare & 0.54 & 3.46 & 0.116 \\ Cultivated & 0.66 & 4.07 & 0.097 \\ Urban & 0.25 & 3.15 & 0.238 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Infiltration parameters from the Burkina Faso National Institute of Geography. Figure 9: Water height (**a**) and flow rates (**b**) at the outlet of the catchment for different values of final infiltration, with 15 mm/h set as the rainfall intensity. Figure 11: Rainfall intensity (**a**) and a comparative study of the water height (**b**), during the flood of 25 July 2017. Figure 10: Location map of the Grand-Cuaga area in Burkina Faso (West Africa). According to the simulation results for case study 2 (Figure 12a), the water reaches its maximum height on the third day (of 4 days) of 3.02 m for the observed values and 3 m for the simulated values. Although the values differ somewhat, the two curves exhibit a nearly identical trend, and the Nash-Sutcliffe value is 0.73. Nevertheless, the findings show a strong link between the two trends. The results from this validation show that the model can simulate the water height at the outlet when the coordinate points are known. The differences observed on the curves of the simulated and measured results are due to certain assumptions, such as the consideration of infiltration parameters and Manning coefficient as constant values over all the land cover. Furthermore, the digital elevation models available for free are long-dated and are not frequently updated according to the evolution of land use.