Evaluation of rainwater harvesting performance for water supply in cities with cold and semi-arid climate

Abstract

In this study, the performance of rainwater harvesting (RWH) was assessed in terms of potential applicability for rainwater saving and non-potable water supply. Rainwater collecting from roofs of buildings was simulated in two cities with cold and semi-arid climate, namely Qazvin and Sanandaj.Rainfall statistics, information on the storage tank size, building roof areas and water demand (non-potable) were obtained. Buildings with roof areas of 100 m 2 to 300 m 2 were considered for the present study. It can be concluded that for cities located in cold and semi-arid climates, at least 60% of non-potable water can be supplied from roofs with a large area, a minimum 16% and maximum 70% for a low roof area, a minimum 8% and maximum 44% of the days per year from harvested rainwater. It is also found that for cities located in cold and semi-arid climates, it is possible to achieve at least 70% of non-potable water from large surface roofs. For the studied cities, with increasing tank size (1,000 to 5,000 L) rainwater saving was tangible for the same roof areas. Key words | cold and semi-arid climate, non-potable water, rainwater harvesting, roof area Palla et al. () examined the performance of domestic RWHs in different European climate zones. Their analysis demonstrated a strong correlation between the performance indexes and the antecedent dry weather period. Jing et al. () assessed the efficiency of RWHs formeeting non-potable water demands in four climatic conditions of China. They found that higher water supply reliability (time reliability) and water storage efficiency were possible for RWHs with a larger storage capacity for lower water demands, while a higher RWH efficiency was in relation to higher water demand, larger saving capacity

Closing Water Cycles in the Built Environment through Nature-Based Solutions: The Contribution of Vertical Greening Systems and Green Roofs

“…For VGS, some literature demonstrates the potential of rainwater use [46,47], but detailed experimental investigation is scarce [48]. Rainwater harvesting systems have proven to be effective as partial substitutes for domestic water demand in oceanic zones [49], as well as in semi-arid climatic zones [50], but limiting factors include the unpredictability of precipitation patterns and the size of water storage systems, which may be prohibitive [14]. On the other hand, wastewater, particularly greywater, is produced daily and, hence, can provide a continuous stream of irrigation water once treated.…”

Comparison of blue-green solutions for urban flood mitigation: A multi-city large-scale analysis

“…Although RWH systems have been developed to collect water in rural areas for irrigation [ 31 ], they can be easily adapted and installed in an urban context, with the aim to mitigate rainfall extremes [ 30 ]. Collected water, if properly treated and stored, can be reused for different purposes, such as irrigation or other non-drinking domestic uses, being a good support to the water supply system [ 32 ]. RWH, however, requires the availability of a large space to locate the water tank, posing some constraints in the general urban planning of the city.…”

Water Conservation and Green Infrastructure Adaptations to Reduce Water Scarcity for Residential Areas with Semi-Arid Climate: Mineral de la Reforma, Mexico

“…A rainwater harvesting (RWH) approach, as a conservation measure, would help people to overcome crises in water supply [7][8][9]. Domestic rainwater harvesting consists of the small-scale concentration, collection, storage, and domestic use of rainwater runoff, mainly from rooftops and other impervious surfaces [10].…”

“…In a rural semi-arid region of central Mexico (annual rainfall of 724 mm), it was possible to capture enough rain for household needs and reduce the work time required to obtain water from local sources [1]. In two Iranian cities with cold and semi-arid climates (annual rainfall varies from 386 and 316.8, respectively), Molaei et al [9] determined that it is possible to obtain at least 70% of non-potable water from large surface roofs (300 m 2 ). Further, RWH has been studied as a viable solution for flood mitigation in sub-Saharan regions' inflow peak and volume reduction at the field and basin-scale [20].…”