Technical feasibility analysis of rainwater harvesting system implementation for domestic use
Introduction
Along with the population growth and rapid urbanization, using rainwater harvesting systems is recommended as a sustainable development solution in water resources management (Moglia, 2019; Rahman, 2017). RWHSs can even be useful and effective with small water tanks during droughts in the Middle Eastern region with a hot and dry climate (Lange et al., 2012).In an urban water-supply system, surface water such as river or lake water and underground water are costly, while rainwater is being considered as a dependable alternative source of water for buildings. Therefore buildings play a vital role in making different approaches to developing the rainwater harvesting system on the urban scale. (Haq, 2017). RWHSs are currently gaining popularity as many communities promote sustainable development (Kindade-Levario, 2007). Also, many studies have examined the benefits of using rainwater harvesting system both in the cities and on the reduction of household consumption (Novak et al., 2014).
Research conducted in Jordon showed that harvesting rainwater from rooftops can supply about 14.7 million cubic metres/years of domestic needs (Abu-Zreig et al., 2013). In Lipari, the largest municipality of the Aeolian archipelago in southern Italy, a study indicated that the annual potential of using RWHS in multi-story buildings is ranged from 30 % to 50 % (Campisano et al., 2017). According to the United States Environmental Protection Agency, 50 to –70 percent of total household water is used for landscape irrigation and other outdoor activities, while personal water bills and the overall demand on public water supplies can be reduced by replacing with captured rainwater (Mechell et al., 2009). In Bangladesh, research stated that the quality of harvested rainwater is acceptable according to Bangladesh standards (Rahman et al., 2014). Research carried out in the Palestinian city of Yatta demonstrated that harvested rainwater can be suitable for drinking water after proper treatments (Al-Batsh et al., 2019).
Based on a study in South Africa, using systems such as rainwater harvesting and gray water can have significant environmental impacts on reducing demand for sewage services, drinking water and conservation of water (Wanjiru and Xia, 2018). Therefore, according to a study in the United States, a 10 % drop in drinking water demand will save around 300 billion kilowatt-hours of energy per year, which will reduce significantly the annual carbon dioxide emissions (Kloss and Lukes, 2008). In Israel, rainwater harvesting has an important impact on the local and regional hydrological cycle and preferable for heavily populated cities (Nachshon et al., 2016). Rainwater harvesting can prevent flood, erosion, and also will decrease the runoff in cities (Kim and Han, 2008; Barthwal et al., 2014; Teston et al., 2018). For example, a study in the United States shows that using this system by the household can reduce, up to 20 % runoff volume in semi-arid regions (Steffen et al., 2013). Many factors influence the design and implementation of RWHS; as in Turkey, it was found that the amount of rain collected in the building, in addition to other factors, depends mainly on the area of the rainwater basin, which is a direct result of the building form. Therefore, investigating the correct decision on the shape of the building can provide a sustainable, climate responsive design (Şahin and Manioğlu, 2019). Cities can achieve sustainability in the water sector if the basis of long-term strategies operated by governments, which can lead to less water use, more reuse water and less pollution of surface water and groundwater (Forssberg et al., 2015). Nowadays, long- term policies that are consistent with sustainable development are needed in developing countries to solve their water crisis. Furthermore, countries with multiple water problems, along with high rainfall, can easily take advantage of the various socio-economic and environmental benefits of RWHSs (Lani et al., 2018).
From the past centuries to the present, the north of Iran is known as the rainy region of the country, due to its geographical location. However, this part of Iran as other regions is facing the global water crisis due to population growth and agriculture (Madani, 2005; Madani et al., 2016). Moreover, Madani claims “Iranians are currently using more than 70 % of their renewable freshwater resources to satisfy their high water demand while using more than 40 % of renewable freshwater resources means entering the water stress mode. “(6) (Madani, 2014). In the North of Iran, despite around 1152 mm average annual rainfall, the feasibility of using the rainwater harvesting system has not been studied in the cities of this region yet. Hence, an appropriate understanding of the applicability of RWHS would be valuable in promoting awareness of the system implementation importance.
Section snippets
Objective
The main purpose of this study is to investigate the technical feasibility of RWHS implementation for saving 5% of potable water demand, which is used for home and garden cleaning, in the residential sector of 7 cities located in the north of Iran. Finally, the influence of roof area variation on the potential of the system and correlation between potable water demand and rainwater tank capacity were examined. Fig. 1 presents the household water consumption per capita per day.
North of Iran
Iran is a country with a population of over 82 million and the 18th largest country in the world located in the Middle East, bordering the Caspian Sea in the north, and the Persian Gulf and Sea of Oman in the south. In this case study, seven cities were selected in three provinces in the north of Iran with humid and semi-humid climates. Fig. 2 illustrates a map of Iran indicating the geographical location of the 7 cities considered in the analysis over the Northern provinces. Fig. 3 shows the
Methodology
In this study to investigate the technical feasibility of RWHS implementation, water balance and compatibility of rainwater tank capacity with the dimension and structure of the dwellings were analysed. In order to accomplish the specified aim, a case was assumed as the criterion sample for each of the seven cities and used historical rainfall data to determine the potential for potable water savings and the rainwater tank capacity by Neptune, which is a computer simulation program. According
Rainfall data
Amongst the 7 cities, rainfall ranged from 523.21 mm per year in the city of Gorgan to 1720.56 mm per year in the city of Anzali, which are located in the provinces of Golestan and Gilan respectively. Fig. 7 illustrates the annual rainfall for the cities analysed in each of the three provinces.
Number of people per dwelling
The average number of people per dwelling for three provinces is considered 3 for the year 2017 according to the Statistical Center of Iran.
Average roof area
The average area of the house and apartment for each city is
Conclusions and future work
The technical feasibility of rainwater harvesting system implementation was investigated in the houses and apartments of the residential sector over the 7 cities located in Gilan, Mazandaran, and Golestan, three Northern provinces of Iran. The potential of RWHS for saving 15 % and 30 % of potable water demand, which is used for home and garden cleaning as a part of typical household water usage in Iran, has been assessed for the houses and apartments over the seven cities respectively. In the
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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2022, Sustainable Cities and SocietyCitation Excerpt :Therefore, for increasing the sustainability of cities and attaining sustainable development in the water sector, governments must encourage long-term measures, devise strategies to reduce water consumption, encourage water reuse and decrease water pollution (Kolavani & Kolavani, 2020). A RWHS plays an important role in sustainable urban development, since the most efficient use of water must be a goal of society in order to achieve sustainability (Abdulla & Al-Shareef, 2009; Kolavani & Kolavani, 2020). RWHS is one of several technologies that assist in increasing sustainability (Ward, Memon & Butler, 2012a), therefore it is understood as a green infrastructure tool aimed to mitigate the effects of urbanization that exerts low impact on a decentralized system in order to meet water demands of society (Wurthmann, 2019).
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2022, Sustainable Cities and SocietyCitation Excerpt :The authors also proposed that HRGs should be implemented in commercial buildings because the required water conservation can almost entirely be met by installing RWHs in residential buildings (Leong et al., 2019). Evaluating decentralized water reuse systems in different building categories is unsuitable for region-level evaluation because common evaluation models such as the linear programming model (Emami Javanmard, Ghaderi & Sangari, 2020), life cycle assessment (Stephan & Stephan, 2017), and the water balance model (Kolavani & Kolavani, 2020; Shadmehri Toosi, Danesh, Ghasemi Tousi & Doulabian, 2020) require detailed data to describe each individual building. As a result, it is impossible to represent the characteristics of each building category via selected case studies, and the conclusions from an evaluation cannot be applied universally in buildings that are of a different scale but in the same category.
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2022, Sustainable Cities and SocietyCitation Excerpt :In a net NZWB, the total annual water usage is equal to the sum of the annual alternative water usage and the total annual water returned to the original water source, i.e. surface water or groundwater sources within an aquifer or watershed similar to that of the building's supply system (Rasekh and McCarthy, 2016; U.S. U.S. Department of Energy, 2015). Several researchers have carried out case-specific research to investigate the performance of alternative supply systems in single housings (Słyś & Stec, 2020; Stec et al., 2017), commercial developments, public buildings, and sport facilities (Burszta-Adamiak and Spychalski, 2021; Chen et al., 2021; da Silva, Oliveira Filho, Silva, E Pinto, & Vaz, 2019; Ghisi et al., 2014), and residential developments (Kolavani and Kolavani, 2020; Zhang et al., 2010). It is demonstrated that greywater reuse is economically attractive as an alternative water supply system for single housing, where the region is water-stressed, and the cost of water is high (Juan et al., 2016).