Confiabilidade volumétrica de reservatórios de acumulação de água de chuva

Abstract

In order to analyze the difference between the usable volume of water calculated on the basis of monthly and daily averages, this paper proposes calculating reliability coefficients for different volumes of reservoir. Using as the method of obtaining the volume passed a mass balance; are considered reservoirs with storage capacity of 5m³, 10m³, 20m³ and 30m³. The catchment area parameters, and consumption were varied, so that a wider range of scenarios could be discussed. Can not be considered however, that in a country with continental dimensions like Brazil the rain behave similarly in all regions. And as the intensity and variability of the same influence in the reservoir efficiency, this study calculated the reliability coefficients for five Brazilian cities, with different precipitation regimes; considering a 25- year data range (1990 to 2014), they were Manaus, Porto Alegre, Campos do Jordao, Irecê and Joao Pessoa. We came to the conclusion that the reliability tends to increase with decreasing of the catchment area and increase of the reservoir volume, occurring however, exception for the city of Manaus. Higher volumes raised tended to have less variability in reliability with the variation of the catchment area. In contrast, low volumes raised, for standards of low consumption, showed reliability of the order of 99%, in other words, the reservoir scaled with the monthly average of precipitation are almost as accurate as the scaled based on daily data. Important point observed also is that the reliability coefficients can not be used without due consideration of the precipitation conditions of the region, as these can vary considerably in a country. Thus, in future studies about the sizing of the reservoir, where the reliability thereof is searched, this factor should be taken into account.