Roof Rainwater Harvesting Systems Research Articles

Rainwater Harvesting Innovations for Flood-Resilient Cities

The expansion of impermeable surfaces in cities have absurdly increased the urban runoff; blocking its pathways to infiltration and evaporation. Rainwater harvesting can be considered as an effective initiative to tone-down the disruptions made to urban runoff pathways.While adopting built form-led solutions from one end to address the consequences of increased urban runoff which eventually increases the frequency and magnitude of urban flooding, rainwater harvesting solutionscan also be adopted in parallel. This study attempts to simulate runoff levelscorrespondent to different vertical-density configurations with reference to a selected micro-watershedin Colombo, Sri Lanka. Simulations were made for four hypothetical built form scenariosin which a roof rainwater harvesting system is in-built: high-rise, intermediate-rise, mid-rise and low-rise. The extent of land and the size population were constant under each scenario. As per the results revealed,low-rise built form was identified as the most disturbing to natural pathways, whereas high-rise built formwas recognized as relatively better options for built-up area expansion.

Promoting rainwater harvesting for improving water security: Analysis of drivers and barriers in Ghana

The study explored strategies and means of achieving wider acceptability and adoption of roof rainwater harvesting (RWH) systems in Ghana to improve water security and availability. The paper employed a qualitative approach in analyzing views expressed by a wide range of stakeholders participating in a workshop on the potential for up-scaling successful RWH technology. Dialogue and content analysis of the views on drivers and barriers to the uptake of RWH technology on a wider scale were synthesized to establish the sustainability of the technology. Some drivers identified included encouraging local fabrication industries to design and/or develop RWH installation components; using the cluster approach in the implementation of RWH technology to ensure cost-effectiveness and wider adoption of the system; and employing the media including television and radio to disseminate the socioeconomic and environmental benefits of the RWH system. Barriers to adoption of the RWH system identified included limited information, high cost of the system, limited institutional support and focus by developers as well as negative perceptions on sustainability and portability from the system. This paper demonstrates the significance of the RWH system as a tool for achieving water security in Ghana. We recommend that to promote wide adoption of the RWH system future studies should investigate the physical and chemical characteristics of harvested rainwater to establish a suitable and acceptable standard for obtained water.

SUSTAINABILITY AND THE SOCIAL CONSTRUCTION OF TECHNOLOGY: THE CASE OF RWH AS SOURCE OF WATER SUPPLY IN GREATER ACCRA

The paper discusses the sustainability of roof rainwater harvesting (RWH) in Greater Accra, Ghana. We take a holistic approach, but focus especially on the social dimension. The discussion is grounded in a research and development project including a holistic sustainability assessment of selected RWH designs based on LCA, cost-benefit analysis and a KAP survey, as well as training of local artisans, stakeholder dialogue and pilot implementation of 21 RWH systems. The performance of the systems largely met the expectation. The households could expect long-term savings, and there were benefits in terms of convenience, hygiene and water sharing. On the other hand, high initial costs, limited awareness, and lack of capacity to implement supportive policies were impediments to wide-scale adoption. The sustainability of the solutions is discussed in further detail. A social construction of technology (SCOT) perspective is applied to throw light on how the stakeholders constructed drivers, barriers, and indeed the technical solutions themselves. We find that the technology was at a stage of low stabilization, meaning-wise, and this clearly affected its sustainability in the local context. The findings suggest that more attention should be paid to socialbconstruction in sustainability research and transition efforts. Keywords: Sustainability, holistic approach, social construction, rainwater harvesting

Reliability analysis of roof rainwater harvesting systems in a semi-arid region of sub-Saharan Africa: case study of Mekelle, Ethiopia

ABSTRACTCurbing water scarcity problems in semi-arid regions is a top priority for economic and social development. Alternative strategies for sustainable domestic water supply are therefore required to augment water supply with affordable cost and technology. Scant research findings in sub-Saharan Africa have, however, reported inefficiency in adapting to water scarcity problems in the region. Therefore, an investigation of domestic rainwater harvesting (RWH) reliability is important to identify factors affecting the system. We found that rainwater harvesting with the existing traditional RWH systems in Mekelle city was unreliable. Unreliability was attributed to inefficient design (the systems were installed without considering deterministically the stochastic nature of rainfall), family size, water demand, rooftop area and storage tank size.Editor M.C. Acreman; Associate editor S. Kanae

Affordability and willingness to install a rooftop rainwater harvesting system: the case of rural households in the Lowveld region of Swaziland

This paper assesses affordability and willingness of rural households in the Lowveld region (drought prone and experiencing water scarcity) of Swaziland to install rooftop rainwater harvesting systems consisting of gutters and storage tanks. Through purposive sampling, 350 heads of households were selected in homesteads which have corrugated iron or tile roofs, and then in-depth face to face interviews conducted. The findings indicate that 93.4% of the households were willing to install rainwater harvesting systems but their economic situation, characterised by low incomes and the high cost of the rainwater harvesting system, inhibited most from doing so. In conclusion the relative low adoption rate of roof rainwater harvesting systems in Swaziland is attributable to affordability challenges and not lack of willingness to install rooftop rainwater harvesting systems. The study recommends that household low interest loans and attractive subsidies should be provided in order to promote the adoption of rainwater harvesting technology.

The Effects of Catchment Materials and Treatment Train on Rainwater Quality in a Rainwater Harvesting System

Recently the interest on rainwater harvesting has been increasing and the installation of rainwater harvesting system (RWHS) has been spread. However, little information is available about influences of catchment materials and system configurations on rainwater quality. This study was performed to examine the rainwater quality according to catchment conditions and system configurations in a roof RWHS. The catchment area of the building #39 in Seoul National University, Seoul, South Korea is 3,652 m2 and consists of the concrete roof, roof garden and marble terrace. RWHS provides water for toilet flushing through the supply facilities. Water quality was analyzed at each catchment area and facilities of the system during rainfall. The pH, EC, turbidity and SS of runoff from the marble terrace showed higher than those of runoff from roof and roof garden. As influences of runoff from terrace and roof garden, turbidity, SS and EC showed high concentration in early part of the RWHS, but those were lower as passing through the system. Catchment conditions should be considered carefully in design of RWHS. Furthermore, the change of water quality due to the arrangement and configurations of the system should be reflected to evaluate water quality in RWHS.