Avaliação do comportamento de cisternas dimensionadas pelo método de Andrade Neto em regiões de diferentes regimes pluviais no Rio Grande do Norte

Abstract

In the context of water scarcity, especially in the semi-arid region, it becomes necessary of the search for alternative solutions that allow the increase of water availability,among which is the use of cisterns for rainwater harvesting. In order to avoid the undersizing or oversizing of these cisterns, its sizing must be done in a careful manner for each specific case, adopting an efficient calculation method and considering, among other factors, the catchment area, demand and the temporal variability of the precipitation. Thus, the objective of this research was to evaluate the behavior of cisterns measured by the Andrade Neto method in regions of different rainfall regimes in Rio Grande do Norte, as well as to develop an empirical equation for the sizing of tanks derived from this method. For this purpose, the efficiency was used to evaluate the behavior of the cisterns, considering different scenarios of roof area and demand. The simulations resulted in cisterns of greater volume for the central region of the state and smaller volumes for the west region, being more efficient in situations where the roof area the roof areas were 150 and 200 m²; and less efficient for roof area of 50 m² and demands greater than 100 l.day-1 .In addition, there were also low efficiencies for regions where there is no monthly critical déficit (Monthly Precipitation> Critical Precipitation), considering the potential volume of rainwater catchable and demand, indicating in these cases be adopted a minimum volume corresponding to the monthly demand required. In relation to the empirical equation for the design of cisterns, obtaining an equation for each of the groups corresponding to the homogeneous rainfall zones of the state was more adequate, being the variables selected were the most relevant for the design of rainwater harvesting systems, the demand, the mean annual rainfall, the critical precipitation and precipitation concentration degree.