Impact of Installing Rainwater Harvesting System on Urban Water Management

The urban-scale impacts of the use of Rainwater Harvesting Systems (RWHS) are little explored within the Brazilian urban and climatic reality. Thus, the objective of this work is to verify the impacts of these systems in reducing runoff and the demand for drinking water, through a case study carried out in a neighborhood in the city of Goiania-GO. In order to carry out the study, the land use characteristics of the studied region were studied from satellite images, with three batch patterns being defined as study scenarios. The daily residential demand for non-drinking uses of water was calculated from the standard lots and the annual rainfall pattern in the city of Goiania, which was also characterized by taking a 30-year historical series of daily rainfall data. With these data in hand, daily water balances were calculated using Excel, for commercial reservoirs of 1, 5 and 10 m(3), in addition to reservoirs with ideal volumes obtained from the NETUNO software. Two balance models were tested and compared and, from them, analyzes were made of the potential for reducing the annual consumption of drinking water in the neighborhood and hydrological simulations were run to verify the flow damping, with the support of the SWMM program. In general, the RWHS use has positive aspects: it reduces the drinking water demand in the neighborhood (up to 37%). However, when analyzing the reduction of peak flows in the drainage system, it is only significant in scenarios with larger reservoirs, confirming its marginal role in stormwater management.

Automated summary

This study examines the impacts of Rainwater Harvesting Systems (RWHS) on reducing runoff and the demand for drinking water in a neighborhood in the city of Goiania-GO, Brazil. The results show that RWHS effectively reduces the demand for drinking water, but its role in stormwater management is limited.