Analysis of Water Supply Feasibility of Urban Rainwater Harvesting Systems

This study conducted a simulation on a test-bed area to evaluate the feasibility of water supply based on annual rainwater usage, depending on the capacity of rainwater storage tanks and daily consumption levels. The analysis showed that larger storage tank capacities led to an increase in the number of days rainwater could be used annually and improved utilization rates, which allowed for the estimation of an appropriate water supply quantity (for agricultural use). Although the rainwater utilization rates remained below 60% for year-round use across various storage tank sizes, the systems were nearly fully utilized during periods of concentrated agricultural water demand when designed at an appropriate scale. Additionally, the larger the storage tank, the higher the seasonal usage efficiency. Also, lower daily usage led to better overall efficiency. Considering monthly and seasonal variability, the study found that an efficient and sustainable continuous supply was relatively better in areas with lower total annual rainfall but minimal seasonal fluctuations and fewer drought periods than in areas with higher but uneven rainfall. This study is expected to provide foundational data for water resource planning by assessing both the soundness of urban water circulation and the feasibility of water supply through rainwater use.