- Graduate Institute of Hydrological and Oceanic Sciences, National Central University, Taoyuan, Taiwan (greentea891030@gmail.com)
In recent years, Taiwan has encountered several severe drought events, with 2021 marking the most extreme drought in over half a century. Our main food crop, paddy, relies on a stable and consistent water supply. To mitigate dependence on reservoir systems, rainwater harvesting has been identified as a promising decentralized water resource management strategy. This study integrates the distribution of paddy fields across cities in Taiwan with daily rainfall grid data from 2003 to 2022. By inputting different agricultural land areas (1,000 m² and 7,000 m²) under first or second crop seasons, along with daily domestic water demand, into the Yield-After-Spillage model, the study calculates water savings, volumetric reliability, satisfied days, and time reliability. This study also employs a rational formula to estimate the added values of rainwater tanks by flood reduction volumes. Finally, the water savings are used to calculate the cost-effectiveness, including net present value and payback period. This study discusses the impact of the spatiotemporal distribution of rainfall on the reliability and water savings of first and second rice cropping periods, as well as analyzes the economic feasibility by cost-effectiveness of varying rainwater tank sizes across different regions under diverse water pricing scenarios. The findings of this research provide practical references for both policymakers and farmers. Policy-makers can evaluate the economic feasibility of the rainwater harvesting systems based on simulation results and then formulate subsidy policies or technical guidelines to promote the efficient use of rainwater resources. Based on the study's recommendations, farmers can select rainwater harvesting solutions tailored to their needs, improving irrigation reliability and cost efficiency.
Keywords: Rainwater Harvesting; Rainwater Tank Size; Cost-effectiveness; Water Savings; Reliability; Flood Reduction.
How to cite: Lo, H. C. and Chen, P.-Y.: Assessing the Economic Feasibility of Rainwater Harvesting in Paddy-irrigation Water Savings and Flood-reduction Potentials in Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3451, https://doi.org/10.5194/egusphere-egu25-3451, 2025.
