Proceedings of the 5th International Conference on Civil Engineering for Sustainable Development (ICCESD 2020), 7~9 February 2020, KUET, Khulna, Bangladesh, 2020
Rainwater harvesting system (RWH) is considered an environmentally sound solution to provide safe... more Rainwater harvesting system (RWH) is considered an environmentally sound solution to provide safe drinking water. It is particularly suitable for Bangladesh because of its having tropical monsoon with a large seasonal cycle in rainfall. Although few studies dealt with the technical feasibility of the RWH system, reliability based cost-benefit analyses are still scarce. This study aims at assessing the financial feasibility of RWH system in Khulna, a coastal district in Bangladesh. We apply a mass balance based behavioral model named 'Yield-After-Spillage (YAS)' to conduct reliability analysis. We use historical as well as future predicted rainfall data in the model to explore the effect of climate change on reliability and financial feasibility. We conducted a social survey to collect necessary information related to RWH system including roof area, roof material, water demand, existing water supply system and cost of materials. Cost-benefit analysis reveals that 85-95% of total RWH installation cost is for the storage reservoir, making it the most expensive unit of the system. We find 'net present value (NPV)' of a typical RWH system positive indicating that RWH is a financially viable solution in the study area. Payback period varies between 3-13 years depending on the precipitation variability. For 100 litre/day demand, predicted rainfall for the 2041-2070 period showed 1.5 times larger storage tank requirement compared to that for historical precipitation scenario to attain 90% volumetric reliability, which results in a substantial increase in cost, and 20% reduction in NPV. However, for 200 litre/day demand, historical precipitation scenario cannot provide more than 53% reliability.
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Papers by Sadia Afrin