## 5 Discussion  
Electric power generation plants relying on water accumulation can either provide solutions or present challenges, contingent on the philosophy guiding the operational  
Figure 12: Recorded drought duration versus duration for the different return periods: 1970–1999, 2000–2010, and 2011–2021. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{\(D_{S,T}\) (Day)} \\ \cline{2-4}
**Tr** & \multicolumn{3}{c}{**Before the Operation of the Hydropower Plant**} \\ \cline{2-4}  & **1970–1999** & **2000–2010** & **2011–2021** \\ \hline
500 & 155.00 & 67.70 & 86.50 \\
100 & 124.00 & 55.50 & 70.50 \\
50 & 111.00 & 50.10 & 63.30 \\
20 & 92.00 & 43.50 & 53.40 \\
10 & 77.30 & 36.40 & 45.40 \\
5 & 61.60 & 29.90 & 36.90 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Drought durations, \(D_{ST}\), for different return periods: 1970–1999, 2000–2010, and 2011–2021. policies of the plant. The operational policies of energy generation must be modified and should take into account the sustainability of river ecosystems, as well as the preservation of human life directly threatened by the lack of water to meet their basic needs [30]. In addition, the operation of the hydroelectric plant should be viewed beyond the energy focus, considering the social responsibility it holds by impacting the sustainability of the communities present in the territory. In the pursuit of the initial specific objective, comprehensive flow data from the Monteria Automatic station were collected. An examination of the base flows revealed a discernible impact of the Urra 1 hydroelectric plant, leading to a notable augmentation in the average river flows. This is attributed to a shift in the operational policies of the plant, wherein the minimum river flows since 2011 have exhibited a substantially higher magnitude, nearly double that in the initial decade of the hydroelectric plant's operation. While this has positively influenced the minimum river streamflows, \(Q_{V}\), it has kept drought durations, \(D_{S}\), slightly higher in the latter period. These observed values undeniably influenced the projections of minimum flows for several return periods, \(Q_{VT}\), and drought durations, \(D_{ST}\), across different return periods. The minimum flows for diverse return periods are listed in Table 7. For the period 2011-2021, the minimum flow values surpass those of the other periods, ranging from 117.00 m\({}^{3}\)/s for 500 years to 129.00 m\({}^{3}\)/s for 5 years. The 2000-2021 period exhibits flows ranging from 12.30 m\({}^{3}\)/s to 68.90 m\({}^{3}\)/s, in which the hydroelectric plant is operational with distinct operating regimes. The minimum flows for various return periods are found in Table 7. For the period 2011-2021, the minimum flow values surpass those of other periods, being 122.00 m\({}^{3}\)/s for a 50-year return period and 129.00 m\({}^{3}\)/s for 5 years. The period from 2000 to 2021 has minimum flows of 28.20 m\({}^{3}\)/s for a 50-year return period and 68.90 m\({}^{3}\)/s for a 5-year occurrence probability, in which the hydroelectric plant is operational with different operating regimes. When comparing the period from 1997 to 1999 with that of 2011 to 2021, we see that the current operational conditions favor an increase in the minimum flow, placing it 88.70 m\({}^{3}\)/s above what would be obtained for a 50-year return period under natural hydrological conditions. Regarding drought durations, \(D_{ST}\), Table 8 reveals that in 2000-2021, i.e., when the Urra 1 hydroelectric plant was in operation, the drought durations were shorter than those in 1972-1999. The latter period represents the natural hydrological and hydraulic conditions of the Sinu River, underscoring that the hydroelectric plant's operation acts as a mitigating factor in reducing the duration of drought days in the river. Furthermore, for a return period of 50 years, a reduction in drought durations of 47.70 days is expected, corresponding to a 42.97% reduction.