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An Overview of Hydropower Reservoirs in Brazil: Current Situation, Future Perspectives and Impacts of Climate Change

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An Overview of Hydropower Reservoirs in Brazil: Current Situation, Future Perspectives and Impacts of Climate Change

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by 1, 2,* 3 and

Diego Tarley Ferreira Nascimento

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Industrial and Systems Engineering Postgraduate Program-MEPROS, Pontifical Catholic University of Goiás, Av. Universitária 1.440, Setor Universitário, Goiânia CEP 74605-010, Goiás, Brazil

Eletrobras Furnas, Industrial and Systems Engineering Postgraduate Program-MEPROS, Pontifical Catholic University of Goiás, BR153, km 510, Zona Rural, Aparecida de Goiânia CEP 74923-650, Goiás, Brazil

School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh EH14 4AS, UK

Geography, Teacher and Humanities Training School, Pontifical Catholic University of Goiás, Av. Universitária 1.440, Setor Universitário, Goiânia CEP 74605-010, Goiás, Brazil

Author to whom correspondence should be addressed.

1. Introduction

Hydroelectric plants are the main sources of electricity in some countries (e.g., Paraguay, Norway, Brazil, Austria and Canada). Hydropower contributes about 85% of global renewable electricity [ 1, 2]. It is the main source of renewable energy in South America, followed by biofuels [ 3]. In several regions of the world (e.g., Southeast Asia and South America), the hydroelectric plants are one of the pillars for the production of renewable energy, but, at the same time, they are vulnerable to the impacts of climate change [ 4]. These changes are causing the majority of the variations in hydroelectric potential [ 5]. Other factors, such as changes in land use and demand for upstream irrigation, can also influence water availability for energy generation [ 5, 6, 7].

Brazil has one of the largest hydroelectric potentials and it is believed that hydroelectricity will continue to play an important role in the next ten years [ 8]. In the country, 80% of the energy generated comes from renewable sources [ 9]. The Brazilian energy matrix is composed mainly of hydroelectric plants (60.9%), followed by fossil fuels (16.11%), biomass (8.74%), eolic (7.52%), import (4.91%), nuclear (1.20%) and solar (0.61%) [ 10]. The 85 solar power plants account for 1,021,602 kW of the installed capacity, and only 0.61% of the energy matrix [ 10]. Even though the country has areas with high solar irradiation, there are no available technologies for its deployment, showing a clear need for investments in national technologies [ 11]. Most of the equipment required for the installation of solar photovoltaic and concentrated solar thermal plants is imported, which implies high costs [ 12].

Water resource use for generation of energy is dependent on hydrological and climatic conditions [ 4, 5, 6, 8, 15, 16, 17, 18, 19]. Global warming may influence the intensity and duration of rainfall, the discharge volume of rivers, the increased evaporation rate of reservoirs and the amount of evapotranspiration of plants [ 20]. Thus, these factors interfere in the water availability for energy generation and may trigger indirect effects such as changes in land use and an increased demand for irrigation [ 18].

Several impacts of climate change on hydroelectric reservoirs can be considered: hydrological changes, variation in sediment load due to flooding, variation in volume and river flow due to changes in precipitation, and the occurrence of extreme events (e.g., droughts and floods) that can generate the need for dam design and safety improvements [ 1, 2, 3, 4, 5, 6, 8].

Hydropower reservoirs are less susceptive to climate change than run-of-river schemes due to its storage capacity as well as being less seasonal flow dependent [ 18]. This resilience depends on dry season duration [ 13]. The changes in the flow affect the level of reservoir and, consequently, the capacity of energy generation [ 18, 19]. In Brazil, there are expectations that future hydroelectric installations will be of run-of-river due to environmental restrictions for the construction of large reservoirs, resulting in the use of the total installed capacity of water flow schemes only during the rainy season. In the dry season, other plants, such as thermoelectric plants, would need to be used to meet the energy demand [ 21].

Climate change must be taken into account in the process of water resources planning and management, so that measures are taken to adapt to future climate scenarios [ 6]. Adaptation strategies for the operation of reservoirs should be implemented [ 5, 16, 22], since hydroelectric plants are fundamental for electricity in Brazil [ 19].

Through a review of the literature, this study aims:

To provide an overview of the current state of hydroelectric plants in Brazil, focusing on reservoir plant types, providing insights into recent policies for the development of hydropower ( Section 2);

To assess the potential for new hydroelectric plants in the country ( Section 3);

To put the current state of hydroelectric plants in Brazil into context in comparison with other countries ( Section 4);

To present the possible impacts of climate change on hydroelectric power generation. To analyse and compare methodologies and results of studies that evaluate the impact of climate change on energy generation by hydroelectric reservoirs ( Section 5);

To identify measures to adapt to future climate scenarios that have been the focus of studies in Brazil and in other countries. ( Section 6);

To present a framework directed to the study of climatic and environmental impact on the generation of hydroelectricity ( Section 7).

2. Current Situation of Brazilian Hydroelectric Plants

Brazil has a great hydroelectric potential, totalling 101,268,561 kW, which corresponds to 60.9% of the energy matrix. There are 1313 operating plants ranging from hydroelectric generation centrals (with up to 1 MW of power installed), small hydropower plants (between 1.1 MW and 30 MW) and hydroelectric power plants (with more than 30 MW). The 218 hydroelectric power plants (HPP) are responsible for 60.5% of the total installed capacity in the country, adding up to 95,619,468 kW. The small hydroelectric plants (SHP), 428 in total, answer for 3.2% of the total installed power. The 667 hydroelectric generation centrals (HGC) in operation account for only 0.4% of the installed power [ 23].

The Serra da Mesa hydroelectric power plant on the Tocantins River has the highest useful volume, at 43.25 km ³; followed by the Tucurui plant, in the same river, at 38.98 km ³, which stands out in terms of installed power at 8370 MW [ 24]. Usually the levels of the reservoirs are higher in the summer, from December to March (more abundant rainy period), and lower between April and November, when there is the dry season [ 8].

Recent studies addressed the current situation of SHP in Brazil, exposing regulations and policies for the growth of the number of plants and the perspectives for the sector [ 25]. Brazilian SHPs are expanding due to their characteristics of small area occupancy and minor environmental impact, besides the possibility of installation closer to the places of consumption, which reduces the loss of energy in the transmission and, consequently, results in a reduction of costs for the consumer.

The main Brazilian hydroelectric reservoirs are in the Paraná river basin. The concentration of hydroelectric power plants is higher in the Midwest, South and Southeast regions ( Figure 1). The Southwest region accounts for 70% of the energy storage capacity. The largest hydroelectric reservoirs are installed near the regions of greatest demand. When full, these reservoirs can store energy to meet the demands for five months, a much shorter period than that observed in the 1970s, when the energy stored in the reservoirs, at maximum capacity, could meet the demand for three or four years [ 26]. These changes arise as a result to the increase in energy demand caused by population growth, in addition to climate and environmental changes.

Recent Policies for the Development of Hydropower

In Brazil, renewable energy sources are considered fundamental for sustainable development [ 28]. Two strategies with regard to the energy sector have been incorporated in Brazil, one focusing on a clean and renewable energy matrix, mainly hydroelectric, and the other promoting efficient use and conservation [ 11]. However, the country needs to review current energy policies in the context of economic growth and also to consider climate change, with investments in energy efficiency, renewable sources and the necessary technological improvements [ 29].

Brazil has opted to increase energy security levels, increase energy generation capacity, and, with this expansion, environmental and social problems have arisen. In order to avoid greater environmental impacts, the main strategy goes towards new projects for run-of-river. However, this policy ends up affecting the generation of energy during dry periods, due to lesser river flow [ 30]. To achieve energy security, the country has invested in hydroelectric and thermal plants, in order to compensate for the lower generation of hydropower during dry periods [ 29].

In run-of-river schemes, energy costs are higher due to the possibility of inactivity in dry periods caused by the absence of a reservoir. The construction time is shorter, on average two years. With regard to environmental impacts, the cumulative effects of several run-of-river installed in the same basin must be considered [ 8]. In addition, the implementation of run-of-river hydropower plants can also contribute to the increase of emissions indirectly, with the need to complement the hydroelectric potential with thermoelectric plants [ 29].

In contrast, large reservoirs maximise electricity production, ensuring greater energy security of the system during periods of drought [ 5, 31]. However, some factors may affect the decision on the construction of hydroelectric reservoirs such as: building time; greenhouse gas emissions; fragmentation of the rivers; changes in water quality; relocating or displacing humans; interference in migration and spawning fish.

The average building time of large dams is 8.6 years [ 32]. Since the 1990s, possible emissions from reservoirs have attracted the attention of several researchers [ 33, 34, 35, 36]. Even though it is a renewable source of energy, there are potential greenhouse gas emissions from reservoirs, such as: methane (CH ₄), nitrous oxide (N ₂O), and carbon dioxide (CO ₂). Large amounts of organic matter remain in the reservoir when the area is flooded, leading to the production of these gases. One of the major concerns is the emission of methane [ 37]. According to Zarfl et al. [ 38], the quantitative emissions depend on how water is released in dams. The release of deep water contributes most significantly for emissions.

Studies carried out in areas in riparian and grassland environments of the Belo Monte hydroelectric complex (Pará) indicate that the most significant concentrations were CO ₂ with a daily mean value of 10,448.41 ± 3036.48 mg m −2 for pasture and 8004.50 ± 1314.98 mg m −2 for forest [ 2]. The Belo Monte mill may produce 1 million tons of CO ₂ per year during the first ten years [ 12, 39]. Dams such as Jirau and Santo Antônio will have lower emissions, due to the size of the reservoirs [ 40].

The amount of emissions varies according to the age of the reservoir, the type of land use before impoundment, management practices, climatic conditions [ 1, 2] and/or the location and morphometry of the reservoir [ 38]. Moreover, it should also be noticed that greenhouse gas emissions in reservoirs are higher in the first 10 years [ 39, 40].

The construction of reservoirs also contribute to the fragmentation of the rivers, relocating or displacing humans (especially of indigenous) [ 38], changes in water quality [ 41], interference in migration and spawning fish, flooding and drainage of areas for fish production [ 42]. Pringle et al. [ 43] relate some fish-related effects: population fragmentation and isolation, migration interference, increases in exotic lentic-adapted species (non-native fishes) and the threat of extinction of some species. Therefore, dams are fundamental for the maintenance of society; however, one must think about environmental sustainability and socio-economic impacts, i.e., the best way to build, operate and maintain dams [ 44].

3. The Potential for New Hydropower Plants in Brazil

4. Comparison to Other Countries

The five largest producers of hydroelectricity in the world are: China, Canada, Brazil, the United States and Russia [ 47]. According to estimates, hydroelectric production may double by 2050, contributing to the reduction of CO ₂ emissions from fossil fuel plants [ 1]. When predicting population growth, water, food, energy consumption and dam development from 2010-2050, Chen et al. [ 44] foresee about 36,813 dams worldwide, with a total reservoir capacity of 9204 km ³ in 2050, and, in 2010, there were 32,473 dams with a capacity of 7975 km ³. In terms of energy consumption, the estimate is an increase from 134,000 to 183,000 TW h.

Future dams will be concentrated in developing countries and emerging economies (Southeast Asia, South America and Africa). Approximately 75% of the dams will be of medium and small size (1-100 MW) and 93% of the future hydroelectric power capacity will be provided by large dams (more than 100 MW). In Brazil, the dams under construction are concentrated in the North and South regions and those planned are in the South and Southeast regions of the country [ 38].

5. Possible Impacts of Climate Change on the Generation of Hydroelectricity

Reduction in average precipitation that implies a reduction in runoff (three to four times).

Increase in average precipitation. Depending on storage and turbine capacity, increased precipitation can lead to an increase in power generation potential. However, this does not always occur, considering that plants are designed for a certain river flow, and the increase of this flow would only lead to unproductive spills.

Increase in average temperature. Rising temperatures will affect soil moisture levels, interfering with the runoff and storage of water in dams. In addition, increase of temperature causes changes in atmospheric pressure and wind patterns. These changes can alter the precipitation patterns [ 30].

Extreme droughts. Depending on the duration of the drought period, the reservoirs act as a buffer, maintaining normal power generation capacity.

Flooding. It entails sediment loads beyond what is expected, and depending on installed capacity, they do not always bring benefits in terms of increasing the potential for generating power.

There are also the indirect impacts of climate change: water scarcity and competition among other sectors (e.g., agriculture, industries, urban consumption); soil degradation and siltation, depending on the vulnerability of the soil to the action of rainwater and river, scarcity of vegetation and soil desiccation during periods of drought, promoting erosion and transport of sediments to reservoirs [ 13].

The most cited studies in the literature on the impact of climate change on hydroelectric power production are that of Christensen et al. [ 48] and Lehner et al. [ 49]. Lehner et al. [ 49] analysed the effects of global changes on Europe's hydroelectric potential by applying the WaterGAP model (Water-Global Assessment and Prognosis) [ 50] for runoff calculations and compared current climate and water use conditions with future scenarios. The study pointed out severe future changes in the discharge regimes that will lead to instability in the European hydroelectric potential that could be reduced by 6% by the 2070s. Christensen et al. [ 48] simulated future climatic conditions and their effects on the Colorado River basin. The results of this study indicated warming, reduced precipitation, decreased runoff and a significant reduction in annual hydroelectric power generation: 56% (2010-2039); 45% (2040-2069); and 53% (2070-2098) in relation to the simulated history.

For South America, the projections indicate an increase in temperature and an increase (or decrease) in precipitation up to 2100; for some regions, there are large uncertainties related to precipitation. Warming varies from 1.7 to 6.7 °C by 2100 and precipitation varies according to the region (−22% in Northeastern Brazil, +25% in South-Eastern South America). In Brazil, the Amazon is highlighted as a hotspot of global warming, a region most vulnerable to climate change [ 3].

In Brazil, few studies have evaluated the impacts of climate change on hydropower reservoirs [ 21, 51]. Some studies have more generally evaluated the impact on river basins, not directly evaluating hydroelectric reservoirs [ 52, 53]. Other studies analysed the vulnerability of hydroelectric generation to changes in climate [ 30, 54].

Soito and Freitas [ 30] reported the risks to energy security in Brazil; the generation of electricity depends significantly on the hydrological availability that can be threatened by increasing water demands (driven by demographic growth and economic development), droughts in the Northeast, and degradation of rivers in the Southeast region (pollution, silting, etc.). In a more recent study, Sorribas et al. [ 53] examined projections of climate change (2070-2099) and their impacts on discharges from the Amazon basin and identified that, for some regions of the basin, there will be an increase in river discharge (Northwest, annual mean +9%) and, for other regions (central Amazon, annual minimum −15.9%), there will be a possible reduction of flow in dry seasons, which may impact the generation of energy from future hydroelectric plants.

Lucena et al. [ 21] evaluated the impacts of climate change on Brazilian river basins. The results point out a tendency for reduction in average annual flow in the period 2071-2100, mainly in the Parnaíba (−10.3%), São Francisco (−26.4%) and Tocantins-Araguaia (−15.8%) basins (North and Northeast regions of Brazil). In the South and Southeast regions, impacts will not be significant, so, in these regions, reservoir management would mitigate the effects of climate change. According to the results of an investigation by Ribeiro Júnior et al. [ 51], if climate change scenarios are confirmed, Furnas reservoir levels may decline sharply. The authors proposed a methodology that considers the determination of the length and transgression frequency of level to minimise the conflicts of water use and the impacts on the generation of energy.

Analysis conducted by Nóbrega et al. [ 55] in the Grand river basin showed an increase in average river flow at the Agua Vermelha reservoir (+10% in the A2 Scenario, from 2508 m ³s −1 to 2748 m ³s −1). Still, according to the study, the increase of 3 °C in global mean temperature can result in an increase in average river flow by 24% (from 2475 m ³s −1 to 3070 m ³s −1) generating flood risks. However, some projections indicate a reduction in average river flow by up to 20%.

The meteorological variables temperature and precipitation are important in climate change studies for hydroelectric management [ 13, 16, 20, 56, 57]. Some authors only model precipitation, considering it the higher impact factor on the availability of water for power generation [ 21]. Other authors propose a combined study between climatic changes and changes in land use [ 6, 7] or between climate changes and demands for irrigation [ 5]. The inclusion of sediment load assessment in hydroelectric basins tends to be a significant contribution to the study of hydrological models. Another approach complements the gap: the need for an analysis of water demand, mainly for irrigation.

Some studies adopt only one scenario, not considering the different views of the general circulation models on the evolution of the climate and its repercussion in terms of the river basins, different from the one done by Haguma et al. [ 6], López-Moreno et al. [ 7], Gaudard et al. [ 17] and Parkinson et al. [ 57]. The use of several scenarios assists in the estimation of different uncertainties involved in hydro-climatic modelling [ 57], such as parameter uncertainty and model structural uncertainty. Climate models that consider a multi-model set, such as ENSEMBLES or CMIP5, provide more reliable assessment since they include different uncertainties [ 4].

Table 3 presents some insights on the possible climatic changes and their consequences in the runoff, flow of the rivers and generation of energy in hydroelectric reservoirs. The table includes the methodology used in each study to evaluate how different uncertainties (observational uncertainty, parameter uncertainty and model structural uncertainty) were included. A comparison between Brazil and other countries was also carried out.

In order to assess the impacts of climate change on water resources, it is necessary to predict the runoff of the basin. A model commonly used is the IHACRES, introduced by Jakeman and Hornberger [ 58], which interfaces climate change input data (temperature and precipitation). The IHACRES is a rainfall-runoff model used to calculate the flow of a river, considering climatic changes.

In some regions, such as in Canada, Manic-5 and Toulnustouc reservoirs, studies indicated positive effects in relation to climate change and power generation. These results are associated with the specific characteristics of the basins; however, as highlighted by the authors, in the long-term, global warming will provide potential negative effects on energy generation [ 6].

6. Adaptations to Reduce Vulnerability and Increase Resilience

The adaptability of hydroelectric schemes to climate change is dependent on local characteristics, specifically: project specifications; storage volume; morphological regime and environmental legislation [ 4, 18]. For example:

Reservoirs with smaller surface area and greater depth tend to be less affected by global warming, which increases evaporation rate of reservoir (according to previous study, 1.1 m depth on average per year) [ 13].

Some hydropower systems offer flexibility of water storage, pump-storage HPP. In periods of lower demands, the water is rebounded to a reservoir with higher elevation, and, in periods of higher demand, the water is released by the turbines. In this case, the generation of hydroelectricity is less dependent on changes in the hydrological regime [ 4]. The limitations for the construction of these hydroelectric schemes in Brazil are related to the establishment of regulatory bases and economic viability.

Optimised operating rules can balance power generation [ 7, 16, 17, 20, 57]. An example of such operational policies would be raising and lowering reservoir level during some seasons. Haguma et al. [ 6] proposed as adaptive operational policies for Manicouagan Reservoir (Canada) the lowering in reservoir water level during winter and raising during spring. For the Furnas HPP reservoir (Brazil), Ribeiro Júnior et al. [ 51] proposed an operative rule that contemplates the time and the cycle of attendance to a certain level of the reservoir, to attend to the generation of energy and to guarantee the sustainability of multiple uses of water for the future climate.

Analyses indicate that hydroelectric managers usually consider historical hydro-meteorological data in the planning and design of new hydropower stations, but data should be also included on the possible impacts of climate change [ 14]. In Brazil, this new strategy is also necessary. With the inclusion of climate change impacts in planning, even if there are changes in flows, the plant can act in a balanced way, reducing losses in energy generation.

The diversification of the energy mix is considered a form of adaptation [ 13]. Thus, in Brazil, different sources of renewable energy can be managed in parallel:

Encouraging the use of solar and wind energy can contribute to the reduction of greenhouse gases and to Brazilian social and economic development [ 28]. Biomass as an energy source is also interesting due to the amount of waste from agriculture and forest products industries, extracted mainly from the sugar and alcohol industry [ 11, 12].

Sources such as biomass (from bagasse and sugar cane straw) and wind power can contribute significantly to the generation of energy in periods with lower rainfall intensity, as it coincides with the more intense potential of these sources [ 8]. It can complement the generation of hydroelectricity in the period of greater fragility, especially the run-of-river hydropower plants.

The great annual variability in the hydrological conditions and the intense rain seasonality can put at risk the Brazilian hydrothermal energy generation system. However, a complementarity between hydroelectric, wind and solar photovoltaic systems could contribute to the stability of production and a decrease in thermoelectric generation [ 71].

7. Discussion

The assessment of projections of climate change allows better understanding of the magnitude of water and energy risks as well as the adoption of adaptation measures to meet future energy demands. The vulnerability and resilience of each hydroelectric plant depends on specific characteristics such as the type of plant (reservoir, pumped-storage or run-of-river), operating strategies, turbine resistance to sediments and the vulnerability of the hydrological regime.

Studies of the impact of climate change on the hydrological regime anticipated possible future developments, but interpretation should cover modelling uncertainties, especially related to climate change scenarios. These studies provided an overview of the trends and enable the establishment of hydroelectric reservoir management strategies. The impacts on the availability of water to the reservoirs can be predicted, which facilitates the designation of a plant operation strategy in order to mitigate the effects throughout the year or the adoption of other measures to guarantee demand to be met.

When establishing adaptive strategies, it is also necessary to investigate the impacts of adaptive actions on ecological integrity of rivers downstream of the reservoir, and there should be concerns related to maintenance of environmental flows, as highlighted in Spalding-Fecher et al. [ 5].

In Brazil, climate change trends indicate that the regions that will suffer the most changes will be the Amazon and the Northeast. Considering the Amazon, strategies should be implemented, due to the clear tendency, for the region, of construction of run-of-river plants, the kind of power plant in which the impacts of global warming are most significant. Considering the Northeast, in strategic terms, the country can opt for complementarity with the development of other renewable sources of energy, such as wind and solar, given its enormous potential for generation, as evaluated in the study of Jong et al. [ 12].

Based on the study of several articles dealing with the impact of climate change on the management of hydropower reservoirs and other related articles, a framework was elaborated ( Figure 3).

This research provides several conclusions related to climate and environmental changes in the context of hydropower reservoirs, which are useful for the academic and industry communities. A summary of the relationship between different variables is presented (see also Figure 3):

Global climate change affects power generation in hydropower reservoirs;

The increase in temperature causes changes in atmospheric pressure and wind patterns and consequently in precipitation and humidity patterns;

The combination of changes in precipitation and temperature affect the moisture levels of soil;

Increase of temperatures results in an increase in potential evaporation;

Changes in wind speed and humidity may compensate for or amplify the increase in temperature, which may interfere with the evaporation rate of the basin and reservoirs;

Precipitation is the climatic variable that most affects the flow of rivers;

Increased precipitation can lead to a rise in river flow; however, the increase in temperature may counterbalance the effect of this rise, as it increases the rate of evaporation of the reservoirs and the evapotranspiration in the basin;

Global warming increases the demand for water for agricultural exploitation (mainly irrigation) and other socio-environmental demands;

Changes in land cover alters the rate of evapotranspiration, which may imply changes in runoff characteristics;

Some changes in land cover can lead to soil degradation (silting), which can affect both the basin and the reservoir level due to sediment transport-aggravating the negative impacts of climate change;

Hydrological impacts vary according to: precipitation intensity, basin characteristics, type of vegetation and/or changes in land cover;

As a chain effect, changes in runoff can affect the production of electricity.

8. Conclusions

In summary, climatic and environmental variables impact the volume of water available for the generation of energy in hydropower reservoirs, hence the need for combined studies (considering these different variables) to develop reliable scenarios for the future availability of water resources for hydroelectric power generation and for the establishment of rules for flexible reservoir operation.

Author Contributions

Viviane de Souza Dias, Marta Pereira da Luz and Gabriela M. Medero performed the studies and wrote the paper. Diego Tarley Ferreira Nascimento has developed the maps and assisted in the paper preparation.

Acknowledgments

The work was supported by the National Council of Scientific and Technological Development (CNPq) through the program Science without Borders, and National Agency of Electric Power (ANEEL)-Project and Development code 0394-1014-2010, through Eletrobras Furnas Company, both from Brazil's government. The authors are also grateful to Coordination for the Improvement of Higher Education Personnel (CAPES) for the granting of the master's degree grant that maintained the first author.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 3. Framework-Climate change and reservoir management.

Region

Name

River

Power (MW)

Useful Volume (km³)

Storable Useful Volume (km³/GW)

Under Construction

Planned

Plant

Power Generated (kW)

River/State

Plant

Power Generated (kW)

River/State

Table 3. Methodologies and main results of studies on impacts of climate change on reservoir management.

Study

Local

Climate Model and Greenhouse Emission Scenarios (IPCC)

Downscaling Method

Components of the Model

Hydrologic Model

Simulation and Optimization Approach

Future Periods

Main Results (Projected Changes)

[ 16]

Karoon-4 reservoir (Iran)

HADCM3 model a (GCM), A2 b

Proportional approach

Temperature and precipitation

IHACRES rainfall-runoff model c [ 58]

Non-dominated sorting genetic algorithm II (NSGA-II)

2025-2039
2055-2069
2085-2099

Temperature: −1.35, −1.45 and −2.20 °C; Precipitation: −18%, −0.4% and −30%;
Inflow to the Karoon4 reservoir would decline in the future periods.

[ 17]

Mauvoisin reservoir and Chanrion run-of-river power plant (Switzerland)

10 regional climate models (RCM)
Ensembles project
(ensembles-eu.metoffice.com), A1B

Delta method

Temperature, scenarios of energy consumption and prices

Glacier Evolution Runoff Model (GERM) [ 59, 60]

Threshold Accepting

2011-2100

Inflows are expected to decrease at average by 18% from 2001-2010 to 2091-2100;
Power generation: −20%;
Power generation after optimization: −16%.

[ 20]

Khersan 1, Karoon 3 and Karoon 4 reservoirs (Iran)

HADCM3 model (GCM), A2

Proportional approach

Temperature and precipitation

IHACRES model

Systems dynamics (SD)/Nonlinear programming (NLP)

2025-2039
2055-2069
2085-2099

Temperature increase;
Decrease of precipitation and inflow;
Power generation (simulation multi-reservoir after optimization): −23%, −7% and −34%.

[ 57]

Reservoirs and run-of-river schems (Canada)

8 GCM with 23 downscaled climate projections, A1B, A2 e B1

Downscaled climate projections of Pacific Climate Impacts Consortium (PCIC)

Temperature and precipitation

Variable Infiltration Capacity (VIC) model [ 61]

Robust optimization

2050

Temperature increase; Increased precipitation trend in most seasons and annually; More runoff available in the winter and spring seasons, and with drier conditions in the summer; Hydropower potential: +11%.

[ 6]

Reservoirs (Manic-5 and Toulnustouc) and run-of-river hydropower plant (Manic-1, Manic-2 and Manic-3) (Canada)

Climate model ensemble
(13 GCM)
A1B, A2 and B1

Downscaling method proposed by Widmann et al. [ 62].

Temperature, precipitation, relative humidity, solar radiation, wind speed, topography and soil types and land uses

Soil and Water Assessment Tool (SWAT)

Sampling Stochastic Dynamic Programming (SSDP)

2010-2039
2040-2069
2070-2099

Temperature (2070-2099): +3 to +10 °C; Precipitation in the winter (2070-2099): +5 to +60%; Annual inflow volume: +4.3%, +9.1% and +13.5%; Average annual power generation: +4.2%, +8.7% and +14.1%); Unproductive Spills increase.

[ 7]

Yesa reservoir (Spain)

Climate model ensemble (12 RCM), A1B

Delta method

Temperature, precipitation, reservoir inflows and outflows, storage level, soil types and land cover

Hydro-Ecologic Simulation System (RHESSys)

-

2021-2050

Temperature: +1 to +2 °C; Annual average rainfall: −10%; Annual streamflow: −13.8%; Annual runoff (considering evolution of land cover): −16%; Annual runoff (combined effects of climate and land cover change): −29.8%.

[ 5]

Major existing and planned new hydropower plants (reservoir and run-of-river) of Zambezi river basin (Southern Africa)

2 GCM (CNRM-CM3 and ECHAM5 MPI-M) d, A2

Direct use of regional models

Temperature, precipitation and irrigation development

Water Evaluation and Planning (WEAP) [ 63, 64, 65]

-

2050-2070

Higher average temperatures; Potentially reducing average electricity generation (12% in the Kariba reservoir); Reduction in the average annual generation in usual irrigation growth (6%); Reduction in the average anual generation when irrigation is prioritized (20% in Cahora Bassa)

[ 66]

Tekeze reservoir (Ethiopia)

CORDEX-Africa (RCM), RCP4.5 and RCP8.5 climate scenarios e

-

Temperature, precipitation, topography and soil types and land uses

Soil and Water Assessment Tool (SWAT)

HEC-ResPRM Optimization Model f

2011-2040
2041-2070
2071-2100

Mean annual temperature: +1.1 °C and +3.38 °C under RCP4.5 and RCP8.5 scenarios; Mean annual precipitation: +45%; Results showed increase in annual and monthly inflow into the reservoir except in dry months from May to June.

[ 21]

Reservoirs (Brazil)

HADCM3 model (GCM), A2 e B2

PRECIS (Providing Regional Climates for Impacts Studies) model (Hadley Centre, UK)

Precipitation

Linear rainfall-flow model for elasticities

SUISHI-O g

2071-2100

Firm power (A2 and B2 emission scenarios, respectively): −1.58% and −3.15%; General negative trend in flow with varying seasonal impacts; São Francisco basin seemed to be the most affected (decrease in energy production would reach more than 7% in the B2 scenario).

[ 51]

Furnas reservoir (Brazil)

HADCM3 model (GCM), A1B

Regional ETA model (National Institute for Space Research-INPE, Brazil)

Temperature, precipitation, relative humidity, solar radiation, wind speed, topography and soil types and land uses

MGB-IPH model h [ 67].

Frequency and duration model

2011-2040
2041-2070
2071-2099

Increased trend of rain rates, not reflecting on flow; Period 2041-2070: prolonged drought, the reservoir can be emptied completely so that the energy demand is met; Increase in generation by 32% while maintaining the fullest reservoir.

Table 4. Adaptations to reduce vulnerability of hydroelectric reservoirs to climate change.

Study

Adaptations to Reduce Vulnerability of Hydroelectric Reservoirs to Climate Change

[ 13]

Obtaining information on the climatic impacts (monitoring of the climate and the runoff of the basins) in the hydroelectric generation and incorporating climatic risks in its management;
Investments in adequate infrastructure, with equipment designed to operate in different climate conditions (e.g., turbine types);
Modernization of plants to enable long-term sustainability;
Development of drought management plans to deal with water competition;
Modifications to operating rules;
Management of land use to reduce soil erosion in the basin and reservoir;
Consideration of the diversification of the energy matrix.

[ 30]

Controlled disposal of industrial waste;
The conservation of vegetation growth;
Regulation of flows of rivers and their tributaries.

AMA Style

De Souza Dias V, Pereira da Luz M, Medero GM, Tarley Ferreira Nascimento D. An Overview of Hydropower Reservoirs in Brazil: Current Situation, Future Perspectives and Impacts of Climate Change. Water. 2018; 10(5):592. https://doi.org/10.3390/w10050592

Chicago/Turabian Style

De Souza Dias, Viviane, Marta Pereira da Luz, Gabriela M. Medero, and Diego Tarley Ferreira Nascimento. 2018. "An Overview of Hydropower Reservoirs in Brazil: Current Situation, Future Perspectives and Impacts of Climate Change" Water 10, no. 5: 592. https://doi.org/10.3390/w10050592

# data[].attributes.attachment_link.title
An Overview of Hydropower Reservoirs in Brazil: Current Situation, Future Perspectives and Impacts of Climate Change

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Global climate change, related to the greenhouse gases emission, impacts hydroelectric power generation mainly due to the increase in air temperature and changes in the precipitation patterns. As a consequence, it affects basin evapotranspiration process, runoff, sediment transport as well as evaporation of reservoirs.

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Impact of Climate change on Water Reservoir

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Impact of Climate change on Water Reservoir

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Lake and Reservoir in Malaysia (Research Article)

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Lake and Reservoir in Malaysia (Research Article)

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Optimizing Reservoir Water Management in a Changing Climate

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Optimizing Reservoir Water Management in a Changing Climate

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Optimizing Reservoir Water Management in a Changing Climate - Water Resources Management

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One of the UN agenda 2030 Sustainable Development goals is associated with water availability and its sustainable management. The present study intends to improve multipurpose reservoir management under climate change scenarios in water scarce regions such as the Mediterranean. Implemented methods include the sequential use of climate model results, hydrological modelling, and reservoir water balance simulation, which are used to estimate future water availability. This work focuses on developing an innovative reservoir management approach based on rule curves and a dynamic assessment of water needs, to improve the management of reservoirs that are dependent on a water transfer system. The proposed methods are implemented in two reservoirs located in a typical Mediterranean river basin and assessed under long-term climate change scenarios up to the year 2100. The results show that the proposed approach can ensure 100% of the urban water supply, improve the reliability of the irrigation supply from 75% to 86–91%, and provide 92–98% of the river ecological flow. It is also demonstrated that this management approach is beneficial, particularly in the case of multipurpose reservoirs in watersheds facing water scarcity risks, to optimize the balance between supply reliability, water transfer volumes, and costs.

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China's Three Gorges Dam is the world's largest, in the size of the dam and reservoir, and in generation capacity.

Photo credit: iStock

By Michael Sutherland

China's Three Gorges Dam is the world's largest, in the size of the dam and reservoir, and in generation capacity. It measures 2,335 m/7,661 ft/1.45 mi long, 181 m/594 ft tall, and required 27.2 million cu m/35.6 million cu yd of concrete. The dam traps a reservoir of 39 cu km/9.4 cu mi volume and 1,084 sq km/419 sq mi, about 2/3 the size of Rhode Island. Its generation capacity is 22.5 GW, and increased China's hydroelectric capacity by nearly 20% when it came on line.

The original concept, to build a 30 million horsepower dam east of the Three Gorges stretch of the Yangtze River, was expressed by the statesman Sun Yat-sen in 1919. The project was alternately pursued and shelved until 1944, when a team of Americans surveyed the region and drew up plans. A team of 54 Chinese engineers went to the US for training and began work, but it was interrupted by the Chinese Revolution. Though Mao Zedong approved of the concept he favored other dams over the Yangtze, and only in the 1980's did debate on it resume. In 1992 the project was approved and in December 1994 work began. Construction was...

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365 Days of Climate Awareness 314 - The Three Gorges Dam

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China's Three Gorges Dam is the world's largest, in the size of the dam and reservoir, and in generation capacity. It measures 2,335 m/7,661 ft/1.45 mi long, 181 m/594 ft tall, and required 27.2...

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Impact of Climate Change on Malaysia's Water Resources

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Impact of Climate Change on Malaysia's Water Resources

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The Impact of Climate Change on Malaysia’s Water Resources: What We Need to Know

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Climate change is having a significant impact on Malaysia’s water resources. As a tropical country, Malaysia is particularly vulnerable to changes in rainfall patterns, increased temperatures, and rising sea levels.

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Climate change on water infrastructure (reservoir)

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Climate change on water infrastructure (reservoir)

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Malaysia’s water infrastructure must be ready for climate change

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Ironically, Malaysia — a country blessed with abundant rainfall — is facing challenges to its water infrastructure due to climate change.

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Water scarcity is increasingly becoming a global problem. Half of the world's population could be living in areas facing water scarcity by as early as 2025, and 700 million people could be displaced because of intense water scarcity by 2030, according to the United Nations Children's Fund (Unicef).

Unfortunately, Malaysia faces this potential catastrophe as well. Based on the Water Resources Study for 2015 to 2050, the northern states of Perlis, Kedah and Penang are projected to experience a water shortage of 221 million to 246 million cubic metres (mcm). Selangor and Melaka could see water shortages of 1,000mcm and nearly 200mcm to 33mcm respectively.

There are multiple factors that contribute to this situation. Monash University School of Engineering associate professor Poh Phaik Eong identifies irresponsible human activities and lack of water catchment areas as the major culprits.

Poh says: "[This happens because] we have less coverage of vegetation such as plants, which have the ability to store water and release it slowly into the ground. If we reduce vegetation coverage, then, obviously, there's no way for water to be captured."

In addition, climate change will result in unpredictable weather patterns, so some areas may experience longer periods of drought. Subsequently, some water catchment areas may not be able to provide sufficient supply of water to communities.

Another challenge that the nation faces is poor drainage management systems in flash flood hotspots.

Poh gives an example of clogged drains at a night market that are caused by irresponsible hawkers who recklessly dump their waste. No additional number of alternative water tunnels will solve the problem of flooding until the drains are cleaned up.

Ultimately, she believes, strong policies and law enforcement - both in regulating businesses and changing public behaviour - are important in alleviating the problem. "This is a personal opinion: The law enforcers are not carrying out strict enforcement to prevent pollution from recurring. Illegal sites are still being set up and [the illegal players] discharging their wastewater into the drain."

Proper wastewater recycling standards are needed, she adds.

Poh's opinion is seconded by Professor Dr Zainura Zainon Noor, the Director of Universiti Teknologi Malaysia's Research Institute for Sustainable Environment.

"A majority of these [water risks] are due to fragmented governance of water," she says. "For instance, although federal agencies have some control over water - for example, the Department of Environment has control over the quality of water - and perhaps the overall policy direction, water resources, in general, are still under the authority of the state government."

Zainura suggests having an integrated platform for both the federal and local governments to work together to ensure that water resources are properly managed.

Beyond relying on dams and putting in huge investments to tackle water scarcity through infrastructure projects, Poh encourages wastewater recycling to be practised by businesses and the public in their individual capacities.

One solution is rainwater harvesting. Also known as rainwater catchment systems, the technology is built to collect and store rainwater for human use. Rainwater harvesting systems range from simple rain barrels to complex structures with pumps, tanks and purification systems to suit different needs.

Water collected from wastewater recycling solutions can be used for secondary activities such as car washing and flushing the toilet.

Based on a study by the Federation of Malaysian Consumers Associations (Fomca), Malaysians have the highest water consumption rate in Southeast Asia of 220 to 250 litres a day. An average consumer should need only 80 litres of water a day, including three litres for drinking purposes, according to Fomca.

Poh believes this bad habit is enabled by heavily subsidised water tariffs, causing people not to appreciate their water supply until a water cut occurs.

To combat this, she suggests that the government increase water tariffs and channel the subsidies to companies that offer wastewater recycling solutions, so it can be affordable enough for the public to install in their homes.

She also advocates for proactive measures to monitor the conditions of waterways in real time. Currently, there are stations placed along waterways to monitor water conditions, but the time duration between each measurement is long, she says.

Poh and her research team are currently developing the Buoy Scout, an unmanned service vehicle that can collect data of water conditions along a designated route and send it to a lab directly for evaluation.

From a business perspective, properties in Malaysia can opt to be certified by the Green Building Index (GBI). An assessed criteria is water efficiency, which can be achieved by rainwater harvesting, water recycling and water-saving fittings.

As at June 2019, there were about 500 GBI-certified local property projects.

For uncertified old shop lots, however, Poh suggests that business owners in the same building invest in a single, integrated wastewater recycling solution rather than purchase separate systems. "It's also down to them to engage with experts to help them see what the wastewater recycling process is all about, which area requires a lot of water or how they can make that process more efficient and reduce water consumption," she says.

Meanwhile, Zainura recommends that businesses adopt corporate water stewardship to reduce water risks.

"Becoming a water steward allows businesses to understand all their water-related risks - physical, reputational, financial and regulatory - and implement strategies to minimise those risks and promote the businesses' long-term sustainability."

Most people tend to forget that the food, energy and water nexus is highly interrelated. If water supply is disrupted, it will affect crops and energy, especially since Malaysia heavily relies on hydropower.

As property and infrastructure development is rapidly transforming landscapes, Poh recommends that society rely more on public transport and walking to reduce the need for road expansion, which results in more loss of vegetation and fewer water catchment areas.

She also suggests that the government look for intermediate solutions to mitigate water scarcity issues. "It's important for us to really understand the consequences of each step that we take before we decide on going down that path. Otherwise, if developments are not properly planned, it will cause a lot of problems for the future generation."

As an educator and researcher, Poh hopes to see more engagement between government agencies and think tanks, as well as a focus on solutions that will slow down the impact of climate change.

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Water scarcity is increasingly becoming a global problem. Half of the world's population could be living in areas facing water scarcity by as early as 2025, and 700 million people could be displaced because of intense water scarcity by 2030, according to the United Nations Children's Fund (Unicef...

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How Reservoirs Are Created | Castle Water

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In the UK, climate change means we’re experiencing uneven weather patterns, with hotter, drier summers, as well as periods where we have very heavy rainfall

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Climate change is affecting drinking water quality

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Climate change is affecting drinking water quality

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Climate change is affecting drinking water quality

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The water stored in reservoirs ensures our supply of drinking water. Good water quality is therefore important -- but is at significant risk due to climate change. In a model study of the Rappbode reservoir in the Harz region, a research team demonstrated how the climate-related disappearance of forests in the catchment area for Germany’s largest drinking water reservoir can affect water quality. The problem of such indirect consequences of climate change is seriously underestimated, the scientists warn. Water quality is of critical importance, especially for drinking water reservoirs, as subsequent treatment in the waterworks must continually meet high standards.