Evaporation from Camargos hydropower plant reservoir: water footprint characterization

Abstract

In recent years, a relevant debate has been raised by a question related to if the hydropower plants indeed represent a non-consumptive use of water resources. In this context, this work was developed at the Camargos Hydropower Plant reservoir, Grande river basin, southern Minas Gerais state, aiming to estimate evaporation rates, which allow the characterization of the Water Footprint in this facility, between the years of 2010 and 2014. Evaporation rates were estimated based on Linacre, Penman and Penman-Monteith methods. Regarding the distribution of evaporation throughout the year, all methods showed the same seasonal pattern, consistent with the meteorological elements behavior that influence this physical process. Although an annual average evaporation considered normal for the studied region (1329 mm) and a small reservoir area (64 km 2 ), this hydropower plant has presented low electric energy production as it is an old facility (more than 50 years) and has low installed capacity. Therefore, Camargos Hydropower Plant has presented, by all methods, a high Water Footprint (130 m 3 .GJ -1 on average) compared to estimates for other hydropower plants in Brazil and worldwide.Keywords: Evaporation; Hydroelectric; Water footprint. RESUMONos últimos anos, um debate relevante tem ocorrido provocado pelo questionamento se as usinas hidrelétricas são de fato de uso não consuntivo dos recursos hídricos. Neste contexto, foi desenvolvido um estudo no reservatório da usina hidrelétrica de Camargos, rio Grande -Minas Gerais, com o objetivo de estimar as taxas de evaporação e caracterizar a pegada hídrica desta usina para o período de 2010 a 2014. A evaporação foi estimada pelos métodos de Linacre, Penman e Penman-Monteith. Em relação à distribuição da evaporação ao longo do ano, todos os métodos apresentaram o mesmo padrão sazonal, condizente com o comportamento das variáveis meteorológicas que influenciam o processo. Apesar de uma evaporação anual média (1329 mm.ano) e da pequena área do reservatório (64 km 2 ), por se tratar de um aproveitamento antigo (mais de 50 anos) e com baixa potência instalada, a geração da usina hidrelétrica de Camargos é pequena, resultando, para todos os métodos avaliados, em uma pegada hídrica elevada (média de 130 m 3 .GJ -1

The Nexus: Estimation of Water Consumption for Hydropower in Brazil

“…The results indicated an average 1,329 mm/year evaporation and showed that in 2014 the evaporation values were higher due to the severe dry season that affected the region. This also shows the importance of calculating evaporation from hydroelectric reservoirs [11]. Finally, Mekonnen and Hoekstra [46] estimated the water footprint of electricity from hydropower for 35 power stations around the world, including 8 from Brazil.…”

“…Despite IPCC's and others' reports, water use from dams for energy generation has traditionally been considered a non-consumptive use in Brazil [9]. Although the Brazilian Electric System National Operator (ONS) did a report on evaporative losses from hydroelectric reservoirs in 2004 [10], these are not considered in water resources planning and management on a river basin level, nor has any extensive research been done since then [11]. In recent years, due to the multiple drought events, the debate has started to slowly resurface as becomes clear from Bueno et al [11] in their work on evaporation and water footprint for the Camargos hydropower plant reservoir, and also Fischmann and Chaffe's [12] work on the water footprint of hydroelectricity in Santa Catarina State, Brazil.…”

“…The scope of this study was constrained by the lack of data availability regarding reservoir properties and electricity generation, especially that of smaller facilities [12]. Also in 2016, Bueno et al [11] published a study that used the water footprint definition by Mekonnen and Hoekstra [46] and calculated the monthly water footprint of the Camargos reservoir. They calculated evaporation for the period between 2010 and 2014 using four methods: Linacre, Penman, Penman-Monteith and the ONS method.…”

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“…The water footprint is directly proportional to evaporation; that is, the greater evaporation, the greater the WFP. Therefore, both the surface area of the reservoir and weather conditions, such as air temperature and solar radiation, directly influence the evaporation (Bueno et al, 2016). In general, hydropower plants have been characterized by a high water footprint, especially in the tropical and subtropical regions, because the water losses by evaporation is higher than in the temperate regions (Bueno and Mello, 2015).…”

Water, energy and agricultural landuse trends at Shiroro hydropower station and environs

“…Adegun et al: Water, energy and agricultural landuse trends at Shiroro hydropower station and environs A number of approaches have been used to estimate the footprint of hydropower reservoirs in different parts of the world. Bueno et al (2016) used the conventional gross water footprint method for the Camargos Hydropower Reservoir in Brazil, and reported that the average hydropower footprint in Brazil exceeded the global average. Herath et al (2011) estimated the hydropower footprint of all major hydropower reservoirs in New Zealand using a combination of the consumptive water use method, the net consumptive water use method, and the net water balance method.…”