# Hydrological Analysis of Extreme Rain Events in a Medium-Sized Basin
## 3 Results
The corresponding indices for each sub-basin regarding all the studied events are displayed in Table 16.  
According to Table 16, regarding the simulation via the HEC-HMS model, the volume error (%) index had low values for all the studied events at all the sub-basins, ranging from \(-27.56\%\) to \(31.69\%\). Concerning the mean absolute volume error of all the studied events in each sub-basin, it was equal to \(11.3\%\) for W1460, \(11.6\%\) for W790, \(8.4\%\) for W800, \(14.8\%\) for W900, \(21.8\%\) for W1030, and \(14.7\%\) for W1020. On the other hand, due to the hydrological simulation of the HBV-light model, the volume error (%) index had higher values in some cases, compared to the values of the other model, varying between \(-47.73\%\) and \(44.75\%\) in all the sub-basins for all the studied events. The mean values of the absolute volume error of all the rainfall events in each sub-basin were equal to \(9.6\%\) for W1460, \(24\%\) for W790, \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Volume Error (\%) due to HEC-HMS**} & \multicolumn{4}{c}{**Volume Error (\%) due to HBV-Light**} \\ \cline{2-13}
**Event** & **W1460** & **W790** & **W800** & **W900** & **W1030** & **W1020** & **W1460** & **W790** & **W800** & **W900** & **W1030** & **W1020** \\ \hline
28–30 May 2013 & \(-19.63\) & \(11.23\) & \(3.93\) & \(21.21\) & \(30.85\) & \(20.70\) & \(18.77\) & \(11.34\) & \(3.22\) & \(27.59\) & \(-2.09\) & \(9.96\) \\
4–10 July 2013 & \(-3.15\) & \(20.25\) & \(-14.27\) & \(31.69\) & \(5.00\) & \(5.45\) & \(-10.55\) & \(-22.85\) & \(-38.36\) & \(-2.69\) & \(-22.90\) & \(-16.17\) \\
7–15 April 2013 & \(-21.24\) & \(-13.85\) & \(-16.64\) & \(-11.94\) & \(-27.56\) & \(-7.22\) & \(6.33\) & \(21.75\) & \(8.52\) & \(-0.58\) & \(-19.68\) & \(2.18\) \\
30 April–7 May 2017 & \(12.61\) & \(5.56\) & \(11.29\) & \(4.14\) & \(24.27\) & \(14.07\) & \(-4.82\) & \(-20.75\) & \(-1.86\) & \(8.83\) & \(44.75\) & \(-0.14\) \\
26–30 June 2010 & \(-7.88\) & \(-0.51\) & \(-3.78\) & \(-19.85\) & \(30.50\) & \(-25.01\) & \(5.93\) & \(19.63\) & \(-1.50\) & \(31.50\) & \(-3.95\) & \(-12.66\) \\
22–25 June 2017 & \(-3.21\) & \(-17.91\) & \(0.55\) & \(-0.24\) & \(12.34\) & \(15.70\) & \(11.29\) & \(-47.73\) & \(-3.19\) & \(3.98\) & \(31.07\) & \(19.24\) \\ \hline \hline \end{tabular}
\end{table} 
Table 16: Volume error per sub-basin for the studied precipitation events. Figure 8: Precipitation, observed and modeled discharge of the 22–25 June 2017 rain event at the six gauged stations. 9.4% for W800, 12.5% for W900, 20.7% for W1030, and 10.1% for W1020. It was obvious that except for sub-basins W790 and W800, in the rest of the sub-basins, the HBV-light model works slightly better than the HEC-HMS model, with the latter working well too. Afterwards, we studied a hypothetical future rain event, based on the 4-10 July 2013 high-intensity event, by increasing the total event observed precipitation by a factor of 1.5, due to the future expected increase in heavy rainfall events in the Eastern parts of Canada. This possible future scenario was considered to investigate the possible increase in the magnitude of modeled runoff with the two hydrological models at the exit of the sub-basin W1020, in which also end up the waters of the sub-basins W1460, W790, W800, and W900, by using the already calibrated values of the parameters. Thus, the total assumed rainfall was 95.1 mm for W1460, 123 mm for W790, 122.4 mm for W800, 115.8 mm for W900, and 160.1 mm for W1020, with corresponding values of maximum precipitation intensity equal to 15, 37.8, 26.9, 37.8, and 39 mm/h. In this scenario, the expected peak runoff reached 571 m\({}^{3}\)/s with the HBV-light model and 481 m\({}^{3}\)/s with the HEC-HMS model, causing an increase of 105% and 85%, respectively, in relation to the modeled peak discharge of the event of 4-10 July 2013 by the two hydrological models.