Impact of large reservoirs on simulated discharges of Brazilian rivers

Abstract

Tens of thousands of dams were built around the world to reduce flood risks, produce energy, and maximize benefits of limited freshwater resources. In Brazil, the main and largest reservoirs are related to hydropower plants. Improving the understanding of reservoir dynamics is important not only to evaluate their impact in the flow regime of Brazilian rivers, but also to simulate the combined effect of constructing new dams and potential alterations under future climatic conditions. Here, we analyze how an ideal representation of reservoirs in terms of forced discharge would improve a previously calibrated hydrological model under the Brazilian domain. We forced the continental-scale version of the MGB model on observed reservoir outflows from 109 hydropower dams, which are part of the Brazilian National Interconnected System controlled by the National Electrical System Operator. Model simulated flows were replaced by the reservoir outflows in all dam locations and were compared to the original discharge in downstream gauges. The forced discharge simulation presented a mean improvement for Kling-Gupta Efficiency of 21%, when compared to the original model (naturalized flow). This analysis is a preliminary step towards an explicit representation of the reservoirs in the model, what will be conducted in a future study.

Accuracy vs Realism: Does including reservoirs improve hydrological models?

“…A study comparable to this one is Passaia et al (2020), which evaluated the model performance across Brazilian rivers when 109 hydropower dams were included in the model. They achieved 21% increase in KGE with including reservoirs in the MGB model, demonstrating that results are, as confirmed by this study, model dependent and might also depend on how the reservoirs are represented in the model.…”

Analysis of Electric Power Transmission Lines Through Graph Theory: Protecting Environmental Preservation Areas Through Strategic Planning

“…In Brazil, electricity generation is predominantly derived from hydroelectric plants, necessitating the transportation of large quantities of energy from generation sites to load centers. To address this requirement, the country has established the National Interconnected System (SIN), which integrates various companies from the north to the south of the country, connecting different regions involved in both electricity production and consumption Passaia et al [25]. In the context of energy generation, significant challenges arise, including the need for expanding transmission lines, particularly in geographically challenging areas like the Amazon region, and ensuring the stability and safety of the electrical system.…”

Flow Measurement Methods in Small Tributaries of the Teles Pires River, Southern of the Amazon Hydrological Region

“…The in situ determination of flow in natural watercourses is fundamental for the definition of key curves and the calibration of hydrological models that allow for the forecasting of flood events, water scarcity, soil loss, and silting of reservoirs, in addition to helping in the taking mitigating measures for these problems, such as implementing appropriate land management practices [9,29], defining hydro-agricultural and forestry projects associated with climate change [30], regulating outflows in reservoirs [31], and supplying water for various human activities [1]. It is also worth mentioning morphodynamic river modeling, which is of paramount relevance to predicting river evolution and preventing hydraulic risk.…”