## 5 Discussion
For a return period of 5 years, there is a reduction of 24.70 days, equivalent to a 40.09% reduction. This comparison is made between the natural hydrological and hydraulic conditions in 1972-1999 and the current operational conditions of the hydroelectric plant (2011-2021). The reductions in drought durations are significant and occur due to the operation of the hydroelectric plant. It is worth noting that, in the operational regime from 2000 to 2010, drought durations are shorter than those projected for the period from 2011 to 2021, clearly indicating that the operation of the hydroelectric plant can considerably mitigate the durations of droughs and the impacts they cause in the region. The results obtained show an increase in the severity of drought durations with the possibility of occurrence for longer return periods. This makes it imperative for riverside communities and governmental establishments to establish risk mitigation policies where, from now on, strategies are designed to preserve human and wildlife life from the impact of droughs. Extended periods of hydrological drought result in a continuous decrease in the level of moisture present in the soil [31]. The operation of the hydroelectric plant, given its confirmed direct impact on maximum, mean, and minimum river flows, should not be solely regarded from the perspective of electricity generation. Alternatively, a comprehensive viewpoint considering the ecosystem sustainability of the territories is advocated. As demonstrated in this study, the operation of the hydroelectric plant has the potential to positively influence both sectors efficiently. The knowledge shared herein contributes to a better understanding of the current interrelation among the Sinu River basin, the Urra 1 hydroelectric plant, and the communities residing within the territories. The results of flow projections for the period from 1972 to 1999 indicate that for a return period of 500 years, there is a drastic decrease in minimum streamflows, \(Q_{VT}\), reaching around 25.00 m\({}^{3}\)/s. This presents the possibility of an extreme drought that could jeopardize the sustainability of ecosystems and riverside communities dependent on the river. For the period between 2000 and 2021, considering it in its entirety, the drought flow for a return period of 500 years is 12.30 m\({}^{3}\)/s, indicating an even more extreme drought. During this period, the Urra 1 hydroelectric plant was in operation. However, when segmenting the period from 2000 to 2021 based on the plant's operational policies, the projected flows for 500 years are 35.40 m\({}^{3}\)/s for the period from 2000 to 2010 and 117.00 m\({}^{3}\)/s for the period from 2011 to 2021. This leads to the conclusion that the operational policies of the hydroelectric plant significantly impact the minimum drought flows in the river, potentially providing the necessary flows to mitigate the risk of extreme droughs in the middle and lower river basins. Still, we must note that similar trends were observed in the other return periods assessed in this research study. Concerning drought durations, for a return period of 500 years, the period from 1972 to 1999 projects an expected drought duration of 155 days, while for the years 2000 to 2021, it is 78 days for the same return period. This underscores that the operation of the hydroelectric plant positively influences drought durations in the river, making them shorter and consequently reducing the negative impact on the territory. In conclusion, the operation of the hydroelectric plant directly influences minimum river streamflows, \(Q_{VT}\), and drought durations, \(D_{ST}\), for different return periods, thereby playing a crucial role in water resource management. Moreover, operational policies for energy generation should not overlook downstream impacts, as they directly affect the risk of extreme droughs in the middle and lower river basins. Conceptualization, A.F.V.-B., A.A.-P. and O.E.C.H. ; methodology, H.M.R. and V.S.F.-M.; formal analysis, A.F.V.-B., A.A.-P. and O.E.C.H.