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Feasibility of rainwater harvesting as an alternative water supply method for rural areas in semi-arid climates
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Mehdi Fard Davaji   , Nader Jandaghi * , Mojtaba Ghareh Mahmoodlu , Amin Mohamadi Ostadkelaye , Mostafa Seyyed |
| Gonbad Kavous University |
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Abstract: (10 Views) |
Introduction: In recent decades, the shortage of freshwater resources, especially in the arid and semi-arid regions of Iran, has become one of the most serious environmental and social challenges. Population growth, urbanization, climate change, and reduced precipitation have placed increasing pressure on surface and groundwater resources, threatening water security in many rural areas. Under these circumstances, rainwater harvesting, as a traditional, low-cost, and environmentally friendly method, has attracted considerable attention. However, concerns remain regarding the chemical and microbial quality of harvested rainwater, particularly after contact with various collection surfaces, which may pose risks to consumer health. This study aims to comprehensively evaluate the physicochemical and hydrochemical characteristics of rainwater harvested from rooftop surfaces in Chenaran village, Maraveh Tappeh, and to assess the feasibility of using this method as a sustainable and safe solution for water supply in arid and semi-arid regions.
Methodology: In this study, to assess the water quality in the region, six types of water sources were selected, including three conventional sources (water reservoir, waterfall, and spring) and three rainwater-harvested sources (collected from bitumen-coated roofs, asbestos roofs, and open surfaces). Rooftop surfaces were thoroughly cleaned before rainfall, and rainwater sampling was conducted 5 to 10 minutes after the onset of precipitation to minimize initial contamination. Sampling was performed in three rounds, with two samples taken from each source and analyzed at two time intervals (immediately and two months post-sampling) to evaluate changes in physicochemical and microbial quality over time. Physicochemical parameters, including electrical conductivity (EC), total dissolved solids (TDS), salinity, turbidity, pH, total hardness, calcium, magnesium, phosphate, potassium, nitrate, and sodium, were measured according to WHO guidelines. Microbial quality was assessed using the presence/absence (P/A) method for indicator bacteria. All analyses were performed based on standard methods, and results were compared with the WHO and ISIRI 1053 standards. Paired t-tests were used to compare physicochemical properties between the two sampling intervals. Additionally, hydrochemical status and water types were evaluated using the cation ratio and Gibbs diagrams.
Results and Discussion: The results showed that rainwater collected in Chenaran village was the purest source in terms of physicochemical quality, with the lowest levels of ions, hardness, turbidity, and TDS, while conventional sources such as the reservoir and spring had higher values for these parameters but still remained within the permissible limits of national (ISIRI 1053) and WHO standards. The turbidity of rainwater and spring was within the desirable range, whereas rainwater collected from bitumen-coated rooftops required treatment due to high turbidity. The statistical analysis using the paired T-test indicated that the mean values of five quality parameters, including phosphate, nitrate, sodium, electrical conductivity, and turbidity, exhibited significant differences between the two sampling periods (p-values: 0.015, 0.000, 0.013, 0.022, and 0.010;
p-value<0.05). In contrast, the least variation between the two periods was observed for the quality factors Ca and TDS, with p-values of 0.562 and 0.508, respectively. The Gibbs diagram analysis indicated that the quality parameters of rainwater sources had an atmospheric origin, while the local sources were influenced by geochemical processes (rock–water interaction). The cationic triangular diagram indicated that the cationic type in some sources, such as the reservoir and waterfall, was sodic, while in others, such as bitumen-coated rooftops, it was calcic. Microbial results showed that the waterfall and spring were contaminated and high-risk for drinking in both periods, whereas rainwater and the reservoir were free of microbial contamination. Overall, with proper collection and storage practices, rainwater can be considered a suitable source for drinking water supply in arid regions, although mineral adjustment and initial treatment are recommended.
Conclusion: The results of this study demonstrated that rainwater harvesting in Chenaran village, when proper collection and storage practices are observed, can serve as a pure and safe source for drinking water supply in arid and semi-arid regions. The collected rainwater exhibited higher quality in terms of physicochemical parameters such as ion concentrations, hardness, turbidity, and TDS compared to conventional local sources, and remained within the permissible limits of national and international standards. Furthermore, the atmospheric origin and absence of microbial contamination in rainwater highlighted its superiority over traditional sources such as springs and waterfalls, which were found to be contaminated and high-risk in both sampling periods. Therefore, the development of rainwater harvesting systems that adhere to health and technical standards, provide user education, and utilize appropriate treatment and storage technologies can play a significant role in enhancing water resilience, reducing dependence on groundwater resources, and improving water security in water-scarce regions of the country.
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| Keywords: Rainwater Harvesting, Physicochemical Characteristics, Microbial Contamination, Gibbs Diagram, Chenaran Village |
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Type of Study: Research |
Subject:
Special
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