Estudo da eficiência de reservatórios de aproveitamento de água de chuva no município de Natal/RN

Abstract

Considering the current scenario of population growth, there was a great increase in the demand for water for human activities, being one reason for the increase in water scarcity. Then, the need to preserve existing fresh water and alternatives to the current form of abstraction was generated. The use of rainwater is a good alternative, since it can be used for less noble purposes and requires water to be potable, but when sanitary protection measures are taken and the treatment is carried out, can be used for drinking purposes. This work aims to evaluate the efficiency of several cisterns in comparison to the water demand and the available roof area, in the city of Natal, located in Rio Grande do Norte (RN). The sizes of cisterns analyzed were 1, 2.5, 5, 10, 15 and 20 m³, daily demands were 50, 100, 150 and 200 liters and for the roof areas 50, 100, 150 and 200 values were assigned m². Based on these data together with the historical pluviometric series of Natal / RN, from 1965 to 2015, 96 simulations were performed in total. By means of the efficiency values obtained it was possible to verify that, for a daily demand of 50 liters, from 50 m² of area and 5 m³ of reservoir size, the efficiency of the system reaches the 90% recommended by Brazilian Regulatory Norm (NBR) 15527 (2007). In the case of higher demands, larger roof areas and reservoirs are required. In addition, a way of calculating efficiency in the Natal municipality was proposed as a function of a dimensionless parameter that correlates the demand, catchment area and reservoir volume.