2025-08-21 トロント大学(U of T)
＜関連情報＞
- https://www.utoronto.ca/news/model-developed-u-t-researchers-could-improve-water-service-more-one-billion-people
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024WR039551
- https://ascelibrary.org/doi/full/10.1061/JWRMD5.WRENG-6090
- https://www.sciencedirect.com/science/article/pii/S0048969723030140
SWMMにおける間欠的な水供給のモデル化：再現可能な推奨事項とPythonパッケージを含む批判的レビュー Modeling Intermittent Water Supply in SWMM: A Critical Review With Reproducible Recommendations and a Python Package
Omar Abdelazeem, David D. J. Meyer
Water Resources Research Published: 31 July 2025
DOI:https://doi.org/10.1029/2024WR039551
Abstract
Distinctly, Intermittent Water Supply networks cycle between filling, pressurized supply and draining, leading users to withdraw water and store it for later consumption. While intermittent networks serve one in five piped water users, their characteristic hydraulic features cannot be readily represented in available, open-source hydraulic modeling software. Several hydraulic modeling methods have been proposed in the literature, but these methods disagree in their construction and assumptions, and most are not reproducible, hindering the exploration of techniques to improve the quality and equality of service in intermittent networks. To improve the reproducibility, consistency, and numerical stability of hydraulic models of intermittent supply, we synthesize the best modeling practices in the literature into a recommended, reproducible method: SWMM for Intermittent Networks (SWMMIN). We outline and demonstrate how SWMMIN models network pipes and user behavior: withdrawing water subject to available pressure in the network, storing water, and consuming from storage for their various activities. For experienced IWS modelers, we provide quantitative evidence of numerical stability and mass conservation within SWMMIN (from >1,000 simulations of 3 network models); we recommend spatial and temporal discretizations that result in solution speeds between 40 and 200 m/s. To facilitate the adoption of our recommended modeling procedures, we share a Python package (GOSWMMIN) that automates the implementation of SWMMIN. Lastly, we propose a model reporting template to bolster reproducibility and call on fellow modelers to use it; accessibly and reproducibly described models of intermittent supply have the potential to accelerate research and transform practice.
Key Points
- Most models of intermittent water supply are not consistent or reproducible, omitting essential features and thwarting research
- We synthesized best practices for modeling intermittent supply in SWMM: pipe filling and draining, user withdrawal, storage, and consumption
- Stability and mass conservation improve in models of intermittent supply when discretization achieves solution speeds of 40–200 m/s
Plain Language Summary
Computer simulations of water pipe networks allow researchers and utilities to test thousands of ways of improving performance. But traditional simulation tools cannot model the behaviour of intermittent systems, which make up one fifth of the world’s water distribution systems. Due to water scarcity, these systems supply water for only a few hours a day or less, forcing households to store water and causing pipes to drain and fill frequently. The few published methods of simulating intermittent supply disagree about how to represent draining, filling and storage; most of these methods are not described in enough detail for others to implement. This paper synthesizes the best of these methods and describes them in enough detail for other modelers to implement. We also provide new evidence and advice about model resolution; we found an ideal ratio of spatial and temporal resolutions that minimizes model error. To make it easier to use our recommended best practices and resolutions, we made an open-source Python package that automatically implements them. Our work makes it easier for researchers and utilities to simulate ways of improving intermittent water supply systems for the one billion people who rely on them.
間欠的な水供給のモデル化方法：モデル選択の比較とその不平等への影響 How to Model an Intermittent Water Supply: Comparing Modeling Choices and Their Impact on Inequality
Omar Abdelazeem, S.M.ASCE , and David D. J. Meyer, Ph.D., A.M.ASCE
Journal of Water Resources Planning and Management Published:Oct 17, 2023
DOI:https://doi.org/10.1061/JWRMD5.WRENG-6090
Abstract
Intermittent water supply (IWS) networks have distinct and complicated hydraulics. During periods without water supply, IWS networks drain, and consumers rely on stored water; when supply resumes, pipes and consumer storage are refilled. Draining, storage, and filling are not easily represented in standard modeling software. We reviewed 30 ways modelers have represented the hydraulics of IWS in open-source modeling tools and synthesized them into eight distinct methods for quantitative comparison. When selecting methods, modelers face two critical choices: (1) whether to ignore the filling phase, and (2) how to represent consumers as attempting to withdraw their demand: as fast as possible (unrestricted), as fast as possible until a desired volume is received (volume-restricted), or just fast enough to receive a desired volume by the end of supply (flow-restricted). We quantify these choices’ impact on consumer demand satisfaction (volume received/volume desired) and inequality using three test networks under two supply durations, implemented in two different hydraulic solvers (EPANET and EPA-SWMM). Predicted inequality and demand satisfaction were substantially affected by the choice to represent consumer withdrawals as unrestricted, volume-restricted, or flow-restricted, but not by the specific implementation (e.g., three different flow-restricted methods agreed within 0.01%). Volume-restricted methods predict wider inequalities than flow-restricted methods and unrestricted methods predict excessive withdrawal. Modeling filling delayed water provision unequally, reducing the volume received by some consumers (by ∼20%), especially where water supply is brief. All else being equal, we recommend using volume-restricted methods, especially when modeling system improvements, and including the filling process when studying inequalities.
Practical Applications
Understanding how water distribution networks perform is complicated, particularly when the network is operated intermittently. Pipes in intermittent networks periodically fill up, supply water, and then drain, forcing consumers to adapt, e.g., by storing water. Intermittent networks represent about 20% of the world’s water pipes, but there are not yet standardized, accessible methods for practitioners and utilities to model the key features of intermittent networks by using or adapting off-the-shelf hydraulic software. Previous methods of adapting hydraulic software for IWS networks disagree on two key choices: how consumers behave and whether to ignore the initial filling of pipes. We quantitatively compare how these varied choices affect the resultant hydraulic predictions. First, we find that when consumers are assumed to fill their storage as fast as they can (volume-restricted), water delivery is less equal than if consumers are assumed to withdraw slower (flow-restricted). Second, we found that including pipe filling delays water supply and magnifies predicted inequalities. Accordingly, we recommend that modelers carefully select methods that reflect how consumers behave in their context. We provide accessibly packaged Python code to enable other hydraulic modelers to efficiently compare, extend, and/or adopt the compared intermittent modeling methods.
間欠的な給水スケジュールからの学び：インドのバンガロールとデリーにおける平等性、公平性、および水力容量の可視化 Learning from intermittent water supply schedules: Visualizing equality, equity, and hydraulic capacity in Bengaluru and Delhi, India
David D.J. Meyer, Saurabh Singh, Jitendra Singh, Manish Kumar, Matthew He
Science of The Total Environment Available online: 25 May 2023
DOI:https://doi.org/10.1016/j.scitotenv.2023.164393
Highlights
- We present new methods to visually learn from intermittent water supply schedules.
- Infrequent, irregular, inconvenient supplies increase consumer storage and water age.
- Average-based indicators obscure inequalities and inequities in intermittent systems.
- Delhi and Bengaluru inequitably have 3278 schedules ranging 24 × 7 to 30 min/week.
- Coincidence of supply schedules suggests hydraulic feasibility of continuous supply.
Abstract
Intermittent distribution affects one in five piped water users, threatens water quality, and magnifies inequity. Research and regulations to improve intermittent systems are hindered by system complexity and missing data. We created four new methods to visually harness insights from intermittent supply schedules and demonstrate these methods in two of the world’s most complicated intermittent systems. First, we created a new way to visualize the varieties of supply continuities (hours/week of supply) and supply frequencies (days between supplies) within complicated intermittent systems. We demonstrated using Delhi and Bengaluru, where 3278 water schedules vary from continuous to only 30 minutes/week. Second, we quantified equality based on how uniformly supply continuity and frequency were divided between neighbourhoods and cities. Delhi provides 45 % more supply continuity than Bengaluru, but with similar inequality. Bengaluru’s infrequent schedules require consumers to store four times more water (for four times longer) than in Delhi, but Bengaluru’s storage burden is more equally shared. Third, we considered supply inequitable where affluent neighbourhoods (using census data) received better service. Neighbourhood wealth was inequitably correlated with the percent of households with piped connections. In Bengaluru, supply continuity and required storage were also inequitably divided. Finally, we inferred hydraulic capacity from the coincidence of supply schedules. Delhi’s highly coincident schedules result in city-wide peak flows 3.8 times their average – sufficient for continuous supply. Bengaluru’s inconvenient nocturnal schedules may indicate upstream hydraulic limitations. Towards improved equity and quality, we provided four new methods to harness key insights from intermittent water supply schedules.
