Decision-making mechanism in appropriate roof selection for rainwater harvesting based on combining field data and laboratory experiments

Abstract

Currently, environmental issues such as global warming and water scarcity are vital and important matter to be concerned about. Sustainable ways to address these problems have been established as effective solutions, and one such example is Rainwater Harvesting (RWH). This research therefore focuses on the sustainable and circular farming practices of crop production and analyzes how different roof designs impact the quality of rainwater used for irrigation. The present research provides a systematic analysis of harvested rainwater (HRW) sourced from nine pilot-scale roofs featuring three roofing materials (i.e., shingle, galvanize metal, and clay tile) and three roof pitch angles (i.e., 5°, 30°, and 42°) at pilot-scale. This holistic evaluation takes into account not only the initial, immediate condition of physicochemical and microbiological quality of HRW but also the potential for long-term agricultural sustainability. To this end, water samples were characterized at the post-collection stage, with special attention given to the combined use of ultrafiltration (UF) and ultraviolet (UV) disinfection, to ensure the standards of irrigation water quality. For the ideal roof design selection for rainwater harvesting it has been involved thorough decision-making process based on six key aspects: Financial, structural, technical, environmental, social, and innovative. Each aspect is divided into four sub criteria, resulting in 24 factors that cover costs, efficiency, environmental impact, and innovative potential. Laboratory tests were conducted to evaluate the water quality parameters. Additionally, expert surveys and literature reviews provided qualitative and quantitative data. The survey responses underwent careful screening to eliminate redundancies and inconsistencies. The Fuzzy Analytical Hierarchy Process (Fuzzy AHP) determined the weight of each criterion, while the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) ranked the roofing configurations. Regarding the detailed considerations of worldwide criteria, the microbial quality of HRW for agricultural applications is of primary importance. It has been emphasized the¬ significance of financial (21.89%) and environmental (19.75%) factors, while¬ the social aspect (11.47%) ranks lower in comparison. The¬ evaluation of criteria reve¬aled that Escherichia coli (E.coli) content (7%), operational e¬xpenses (6.78%), and reduce¬d runoff (5.73%) were crucial considerations for harve¬sted rainwater. Among the roof configurations asse¬ssed, galvanized metal roofs with a 5° angle¬ emerged as the¬ superior choice due to the¬ir structural, technical, and environmentally frie¬ndly advantages. Incorporating expert insights into the¬ multi-dimensional evaluation of roof configurations provides a valuable¬ tool for assessing qualitative aspects, such as innovation, which might otherwise be overlooke¬d. It has been systematized a robust, circular economy-base¬d decision-making approach for more straightforward roof sele¬ction in rainwater harvesting, offering a compre¬hensive perspe¬ctive through a comprehensive¬ set of factors. In this case, E.coli plays a major role in defining the microbiological safety level. In the order of significance; operational cost, runoff reduction, investment cost, and construction complexity present an inclusive picture of RWH system selection that takes into account many aspects. The outcomes of the survey confirm that the most optimal material to be used in RWH systems is galvanized metal, which was also identified for high performance due to complete compliance with all ecological, technical, and structural parameters. This research confirms the practical application of galvanized metal in the sphere of RWH. This study, while covering an extensive scope, still has limitations; hence, additional methods that can be applied in future studies may include methodological improvements involving the use of different criteria weighting techniques and amalgamation with fuzzy set theory. These studies can also be based on alternative prioritization methods such as vlsekriterijumska optimizacija i kompromisno resenje (VIKOR), meaning "multicriteria optimization and compromise solution", preference ranking organization method for enrichment evaluations (PROMETHEE), and elimination and choice expressing reality (ELECTRE) to ensure improvement in decision-making processes. Moreover, sensitivity analysis and Monte Carlo simulations help researchers gain deeper insights into criteria relationships and the reliability of findings, respectively. In terms of concepts, the research thus reveals the potential of case studies to determine the case studies in different areas using real roof structure's data for checking and possibly improving the provided frame. Also, integration of the regenerate, share, optimize, loop, virtualize, exchange (RESOLVE) framework and essence-wheel might provide unexplored views as well as an excellent deal with new avenues for investigation directed towards water resource use optimization for the circular economy. In summary, this thesis offers a strategic guide for optimizing RWH systems for the circular economy in the agricultural context and also offers a critical lens by which to view the current international water management paradigm, supporting, as it does a generic circular economy vision of the future, replete with closed circles of materials, energy and water.