Luo et al. (2026) Spatiotemporal assessment of rainwater harvesting efficiency for multi-story residential buildings across different climate zones in China

Identification

• Journal: Ecological Indicators
• Year: 2026
• Date: 2026-01-01
• Authors: Pingping Luo, Ziwen Wang, Manting Luo, Jiachao Chen, Yubin Zhang, Meimei Zhou, Jianxin Zhang, Binaya Kumar Mishra, Maochuan Hu, Ahmed Elbeltagi
• DOI: 10.1016/j.ecolind.2025.114531

Research Groups

• Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Chang’an University, Ministry of Education, Xi’an, Shaanxi Province, China
• School of Water and Environment, Chang’an University, Xi’an, Shaanxi Province, China
• Shaanxi Province Innovation and Introduction Base for Discipline of Urban and Rural Water Security and Rural Revitalization in Arid Areas, Chang’an University, Xi’an, Shaanxi Province, China
• Xi’an Monitoring, Modelling and Early Warning of Watershed Spatial Hydrology International Science and Technology Cooperation Base, Chang’an University, Xi’an, Shaanxi Province, China
• Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of the Ministry of Water Resources, Chang’an University, Xi’an, Shaanxi Province, China
• Graduate School of Engineering, Kyoto University, Kyoto, Japan
• School of Land Engineering, Chang’an University, Xi’an, China
• School of Architecture, Chang’an University, Xi’an, China
• School of Engineering, Faculty of Science and Technology, Pokhara University, Pokhara, Nepal
• School of Civil Engineering, Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
• Agricultural Engineering Department, Faculty of Agriculture, Mansoura University, Mansoura, Egypt

Short Summary

This study assessed the spatiotemporal efficiency of rainwater harvesting (RWH) systems for multi-story residential buildings across three distinct climate zones in China, revealing that tank size is critical in humid regions while rainfall availability and water use scenarios dominate efficiency and reliability in semi-humid and semi-arid areas.

Objective

• Quantify the rainwater management performance and water conservation efficiency of rainwater harvesting systems under representative wet, average, and dry hydrological years across diverse Chinese cities.
• Evaluate how spatial variability in rainfall patterns influences the operational reliability of rainwater storage infrastructure (tanks).
• Identify the most effective tank capacity and rainwater utilization strategy tailored to local environmental and demand conditions.

Study Configuration

• Spatial Scale: Three Chinese cities representing humid (Wuhan), semi-humid (Xi’an), and semi-arid (Xining) climate zones; multi-story residential buildings with a 1000 square meter rooftop and 2000 square meter adjacent lawns, serving approximately 100 residents.
• Temporal Scale: Three representative hydrological years (wet, average, dry) selected from 60 years (1960–2019) of daily rainfall data; simulations conducted on a daily time step, with results accumulated to an annual scale.

Methodology and Data

• Models used: A daily water balance model developed in MATLAB, based on a behavioral type model (yield-before-spillage), to simulate RWH system performance.
• Data sources: Daily rainfall data from the National Climate Center of China (1960–2019); residential building population (100 people); lawn irrigation area (2000 square meters); per capita daily toilet flushing water consumption (32 liters per person per day); average annual lawn irrigation quotas for cold-season type (0.50 cubic meters per square meter per year for Wuhan, 0.28 cubic meters per square meter per year for Xi’an/Xining); irrigation period (April–October, 210 days).

Main Results

• Humid Zone (Wuhan): Increasing tank size significantly improves RWH efficiency. Rainwater Collection Efficiency (WCE) reached a peak of 81.44% at a tank volume of 118 cubic meters for combined use in an average year. Reliability for lawn irrigation reached 100% in average and wet years with tank volumes exceeding 150 cubic meters. Optimal tank volumes ranged from 60 cubic meters to 230 cubic meters depending on the year and water use scenario.
• Semi-Humid (Xi’an) and Semi-Arid (Xining) Zones: Rainfall availability is the primary factor affecting Water Saving Efficiency (WSE). WCE and WSE plateau at relatively low tank volumes (e.g., ~50 cubic meters in Xining) due to limited rainfall. WSE in Xining was low, with a maximum of only 33.67% even in wet years. Reliability was significantly lower than in Wuhan, with toilet flushing and combined use scenarios showing very low reliability (2.74%–23.84% in Xining). Optimal tank volumes were generally not achievable, except for lawn irrigation in wet years in Xi'an (150–200 cubic meters).
• Water Use Scenarios: Lawn irrigation (low demand) consistently achieved higher WCE, WSE, and reliability compared to toilet flushing or combined use, particularly in drier regions.
• Overflow Ratio: Higher in Wuhan, reaching up to 50% for lawn irrigation in wet years with a 250 cubic meter tank. In Xi'an and Xining, the overflow ratio could be reduced to 0 with tank volumes of 200 cubic meters and 50 cubic meters, respectively.
• Optimal Tank Volume Determination: Defined by WSE ≥ 50% and overflow rate ≤ 10%. Humid zones showed a broader range of optimal volumes, semi-humid zones only achieved optimal volumes for low-demand scenarios in wet years, and semi-arid zones generally lacked an optimal range, suggesting RWH for emergency water replenishment.

Contributions

• Established a novel three-dimensional assessment framework integrating three climate zones, three typical hydrological years (wet, normal, dry), and three water usage scenarios, addressing limitations of existing studies.
• Developed a MATLAB-based computational tool that simultaneously outputs interrelated results for rainwater collection efficiency, water-saving efficiency, overflow rate, and reliability, suitable for engineering design.
• Quantified the interaction effects of climate zone, typical year, and water usage scenario, providing a quantitative basis for differentiated rainwater management strategies.
• Provided an integrated decision support tool for urban water authorities, offering optimal construction options and combinations of water use pathways and tank volumes for various geographical locations.

Funding

• Hunan Provincial Water Conservancy Science and Technology Project (No.: XSKJ2025056-17, Research on Intelligent Flood Early Warning and Emergency Risk Avoidance Countermeasures in the Miluo River Basin)
• Shaanxi Provincial Department of Education “Urban and Rural Spatial Hydrological Ecological Simulation and Management in Arid Area“ Youth University Innovation Team
• International Education Research Program of Chang’an University Project of Ningxia Natural Science Foundation (2022AAC03700, 2022BEG03059)
• Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing, China (Grant NO. YSS2022004)

Citation

@article{Luo2026Spatiotemporal,
  author = {Luo, Pingping and Wang, Ziwen and Luo, Manting and Chen, Jiachao and Zhang, Yubin and Zhou, Meimei and Zhang, Jianxin and Mishra, Binaya Kumar and Hu, Maochuan and Elbeltagi, Ahmed},
  title = {Spatiotemporal assessment of rainwater harvesting efficiency for multi-story residential buildings across different climate zones in China},
  journal = {Ecological Indicators},
  year = {2026},
  doi = {10.1016/j.ecolind.2025.114531},
  url = {https://doi.org/10.1016/j.ecolind.2025.114531}
}