Potential for rainwater harvesting in a dry climate: Assessments in a semiarid region in northeast Brazil

Abstract

In the last few years, a rapid increase in the population has been observed in many places. The majority of the population lives in urban areas, and experiences several problems related to an inefficient water supply and the occurrence of precipitation extreme events, such as a long dry season or the occurrence of floods. This framework allows consideration of the harvesting and storage of rainwater in tanks for immediate or future use. The harvesting, storage and use of rainwater in urban areas can create a positive impact on the public water supply system through a reduction in the demand for and use of potable water. Brazil experiences both water scarcity and abundance, due to the large dimensions of the country, imbalances in the population distribution and the timing of precipitation. From north to south, there is a wide variety of climates with distinct regional characteristics, including areas of semiarid climate; these are at risk of flooding due to rainfall concentration in few heavy showers and, on the other hand, are also susceptible to drought. Based on precipitation data and other information, an investigation was carried out into the potential of rainwater harvesting in the semiarid region of Brazil. There are 1133 municipalities within the defined semiarid region of Brazil; these municipalities are in nine states (Ministry of National Integration, 2005), including Pernambuco. In this region, the conventional public drinking water supply system covers 60% of the population, distributing water nine and five days per month to the inhabitants of the urban and rural areas, respectively. The potential for potable water savings was estimated for the urban areas of several cities within the semiarid region in Pernambuco State, northeast Brazil, using the methodology proposed by Ghisi et al. (2006) and Belmeziti et al. (2013). Ghisi et al. (2006) applied this methodology to cities in the southern region of Brazil and Belmeziti et al. (2013) used the methodology proposed in Municipality of Colombes (Paris Region). The results show that savings in water supplied by the public system can reach 25%; this paper discusses in an innovative way the savings in water supplied by the public system in a dry climate. The results indicate that a reduction in the pressure on the public water supply system is possible, simply by incorporating rainwater harvesting into the standard practices of local inhabitants.