State Key Laboratory of Efficient Production of Forest Resources, School of Soil and Water Conservation, Beijing Forestry University, Beijing, 100083, China; National Station for Forest Ecosystem Research in Ji County, Ji County, Shanxi, 042200, China.
State Key Laboratory of Efficient Production of Forest Resources, School of Soil and Water Conservation, Beijing Forestry University, Beijing, 100083, China; National Station for Forest Ecosystem Research in Ji County, Ji County, Shanxi, 042200, China; Beijing Engineering Research Center of Soil and Water Conservation, Beijing, 100083, China.
J Environ Manage. 2024 Nov;370:122722. doi: 10.1016/j.jenvman.2024.122722. Epub 2024 Oct 11.
Rainwater Harvesting Systems (RHS) are widely implemented to mitigate urban water shortages, yet the impacts of compatibility between rainwater availability and water demand on their performance are often overlooked. This study introduces novel rainwater deficit and surplus indices to quantitatively assess the impacts of compatibility between rainwater availability and water demand on the performance of RHS across 16 cities in different climate zones and under 3 daily water demand scenarios. The rainwater deficit and surplus indices, and the water saving efficiency and reliability of RHS are calculated based on long-term (1991-2020) continuous simulations using a daily water balance model. Results show the rainwater deficit index effectively quantifies water supply pressure on RHS, while the rainwater surplus index quantitatively evaluates their water saving potential. Both of water saving efficiency and reliability of RHS significantly linearly decrease with the rainwater deficit index (P < 0.05), and the coefficients of determination (R) decrease from 0.96 to 0.80 as tank size increases from 1 to 300 m. Both of water saving efficiency and reliability increase along sigmoid curves with the rainwater surplus index (P < 0.05), and R values increase from 0.91 to 0.99 with tank size. The results indicate that tank size optimization enhances water saving performance of RHS through reducing deficits and surpluses. However, the performance enhancement by tank size optimization could be limited by the compatibility between rainwater availability and water demand. Taken Kashgar (arid climate) as an example, the thresholds of water saving efficiency under all water demand scenarios are below 15% due to high rainwater deficit and low surplus. This study emphasizes that the compatibility between rainwater availability and water demand should be considered in planning and design of RHS.
雨水收集系统（RHS）被广泛应用于缓解城市水资源短缺问题，但雨水供应与需求之间的兼容性对其性能的影响往往被忽视。本研究引入了新颖的雨水亏缺和盈余指数，以定量评估雨水供应与需求之间的兼容性对不同气候区 16 个城市和 3 种日需水量情景下 RHS 性能的影响。基于每日水量平衡模型，利用长期（1991-2020 年）连续模拟，计算了雨水亏缺和盈余指数、RHS 的节水效率和可靠性。结果表明，雨水亏缺指数有效地量化了 RHS 的供水压力，而雨水盈余指数则定量评估了其节水潜力。RHS 的节水效率和可靠性均随雨水亏缺指数显著线性下降（P<0.05），随着水箱尺寸从 1 增加到 300m，决定系数（R）从 0.96 减小到 0.80。RHS 的节水效率和可靠性随雨水盈余指数呈类 S 形曲线增加（P<0.05），随着水箱尺寸增加，R 值从 0.91 增加到 0.99。结果表明，通过减少亏缺和盈余，水箱尺寸优化可以提高 RHS 的节水性能。然而，由于雨水供应与需求之间的兼容性，水箱尺寸优化带来的性能提升可能会受到限制。以喀什（干旱气候）为例，由于雨水亏缺高和盈余低，所有需水情景下的节水效率阈值均低于 15%。本研究强调，在 RHS 的规划和设计中应考虑雨水供应与需求之间的兼容性。
