Editorial

6 pages, 498 KiB

Open AccessEditorial

Resilience of Interdependent Urban Water Systems

by Robert Sitzenfrei, Kegong Diao and David Butler

Water 2022, 14(3), 440; https://doi.org/10.3390/w14030440 - 01 Feb 2022

Cited by 3 | Viewed by 2083

The reliable functioning of water infrastructures is one of the key pillars for society, and it is crucial for social well-being and supports economic growth [...] Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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Research

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17 pages, 3040 KiB

Open AccessArticle

Stress-Testing Framework for Urban Water Systems: A Source to Tap Approach for Stochastic Resilience Assessment

by Dionysios Nikolopoulos, Panagiotis Kossieris, Ioannis Tsoukalas and Christos Makropoulos

Water 2022, 14(2), 154; https://doi.org/10.3390/w14020154 - 07 Jan 2022

Cited by 8 | Viewed by 2085

Abstract

Optimizing the design and operation of an Urban Water System (UWS) faces significant challenges over its lifespan to account for the uncertainties of important stressors that arise from population growth rates, climate change factors, or shifting demand patterns. The analysis of a UWS’s [...] Read more.

Optimizing the design and operation of an Urban Water System (UWS) faces significant challenges over its lifespan to account for the uncertainties of important stressors that arise from population growth rates, climate change factors, or shifting demand patterns. The analysis of a UWS’s performance across interdependent subsystems benefits from a multi-model approach where different designs are tested against a variety of metrics and in different times scales for each subsystem. In this work, we present a stress-testing framework for UWSs that assesses the system’s resilience, i.e., the degree to which a UWS continues to perform under progressively increasing disturbance (deviation from normal operating conditions). The framework is underpinned by a modeling chain that covers the entire water cycle, in a source-to-tap manner, coupling a water resources management model, a hydraulic water distribution model, and a water demand generation model. An additional stochastic simulation module enables the representation and modeling of uncertainty throughout the water cycle. We demonstrate the framework by “stress-testing” a synthetic UWS case study with an ensemble of scenarios whose parameters are stochastically changing within the UWS simulation timeframe and quantify the uncertainty in the estimation of the system’s resilience. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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24 pages, 8028 KiB

Open AccessArticle

Seismic Performance Assessment of Water Distribution Systems Based on Multi-Indexed Nodal Importance

by Benwei Hou, Xitao Ma, Kegong Diao, Zilan Zhong and Shan Wu

Water 2021, 13(17), 2362; https://doi.org/10.3390/w13172362 - 28 Aug 2021

Cited by 5 | Viewed by 2293

Abstract

Seismic performance assessment of water distribution systems (WDSs) based on hydraulic simulation is essential for resilience evaluation of WDSs under earthquake disasters. The assessment is mainly to determine how the water supply will be affected due to pipe breaks caused by the earthquake, [...] Read more.

Seismic performance assessment of water distribution systems (WDSs) based on hydraulic simulation is essential for resilience evaluation of WDSs under earthquake disasters. The assessment is mainly to determine how the water supply will be affected due to pipe breaks caused by the earthquake, with the water supply loss estimated based on the loss of supply to nodes. Existing research works usually use the average or overall performance metric of all user nodes as the system performance indicator without considering user nodes’ individual performance and criticality. This paper proposes a framework to evaluate the importance of user nodes considering post-earthquake rescue service and the seismic performance of individual user nodes in the WDS, which supports the pipeline renovation plan to improve the performance of critical user nodes. The importance of user nodes is evaluated by a multi-index model, including the indices for daily service, post-earthquake rescue service, and network topology influence of user nodes. These indices evaluate the importance of user nodes in terms of their roles for daily water service, emergent rescue service, and water transmission to other nodes, respectively. Fragility model of pipelines evaluates the earthquake-induced damages of the WDS, and the seismic performance assessment of the WDS system is performed by the hydraulic model of the WDS with pipeline damages. The proposed framework is implemented in an actual WDS; the results show that the importance classification to user nodes by multi-index approach can identify the critical user nodes for post-earthquake rescue service, which traditional methods may ignore. The importance classification and seismic performance of individual user nodes make it feasible to check the seismic performance of critical user nodes and formulate a targeted pipeline renovation plan to focus limited resources on critical user nodes. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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20 pages, 1704 KiB

Open AccessArticle

A Method for Modeling Urban Water Infrastructures Combining Geo-Referenced Data

by Imke-Sophie Rehm, John Friesen, Kevin Pouls, Christoph Busch, Hannes Taubenböck and Peter F. Pelz

Water 2021, 13(16), 2299; https://doi.org/10.3390/w13162299 - 22 Aug 2021

Cited by 5 | Viewed by 2787

Abstract

Water distribution networks are the backbone of any municipal water supply. Their task is to supply the population regardless of the respective demand. High resilience of these infrastructures is of great importance and has brought these infrastructures into the focus of science and [...] Read more.

Water distribution networks are the backbone of any municipal water supply. Their task is to supply the population regardless of the respective demand. High resilience of these infrastructures is of great importance and has brought these infrastructures into the focus of science and politics. At the same time, the data collected is highly sensitive and often openly unavailable. Therefore, researchers have to rely on models that represent the topology of these infrastructures. In this work, a model is developed that allows the topology of an urban water infrastructure to be mapped using the example of Cologne, Germany by combining freely available data. On the one hand, spatial data on land use (local climate zones) are used to disaggregate the water demand within the city under consideration. On the other hand, the parallelism of water and urban transportation infrastructures is used to identify the topology of a network by applying optimization methods. These networks can be analyzed to identify vulnerable areas within urban structures. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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19 pages, 1097 KiB

Open AccessArticle

Water Distribution in a Socio-Technical System: Resilience Assessment for Critical Events Causing Demand Relocation

by Kevin T. Logan, Michaela Leštáková, Nadja Thiessen, Jens Ivo Engels and Peter F. Pelz

Water 2021, 13(15), 2062; https://doi.org/10.3390/w13152062 - 29 Jul 2021

Cited by 5 | Viewed by 2596

Abstract

This study presents an exploratory, historically-informed approach to assessing resilience for critical events that cause demand relocation within a water distribution system (WDS). Considering WDS as an interdependent socio-technical system, demand relocation is regarded as a critical factor that can affect resilience similarly [...] Read more.

This study presents an exploratory, historically-informed approach to assessing resilience for critical events that cause demand relocation within a water distribution system (WDS). Considering WDS as an interdependent socio-technical system, demand relocation is regarded as a critical factor that can affect resilience similarly to the more commonly analyzed component failures such as pipe leaks and pump failures. Critical events are modeled as events during which consumer nodes are evacuated within a perimeter varying in size according to a typical length scale in the studied network. The required demand drops to zero in the evacuated area, and the equivalent demand is relocated according to three sheltering schemes. Results are presented for analyzing the effect of the size of the evacuated area, the feasibility of sheltering schemes, vulnerability of particular parts of the city as well as the suitability of network nodes to accommodate relocated demand using a suitable resilience metric. The results provided by this metric are compared with those drawn from common graph-based metrics. The conclusions are critically discussed under the consideration of historical knowledge to serve as a basis for future research to refine resilience assessment of socio-technical systems. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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20 pages, 3416 KiB

Open AccessFeature PaperArticle

Optimal Implementation of Wastewater Reuse in Existing Sewerage Systems to Improve Resilience and Sustainability in Water Supply Systems

by Aakash Dev, Timo C. Dilly, Amin E. Bakhshipour, Ulrich Dittmer and S. Murty Bhallamudi

Water 2021, 13(15), 2004; https://doi.org/10.3390/w13152004 - 21 Jul 2021

Cited by 8 | Viewed by 2861

Abstract

A transition from conventional centralized to hybrid decentralized systems has been increasingly advised recently due to their capability to enhance the resilience and sustainability of urban water supply systems. Reusing treated wastewater for non-potable purposes is a promising opportunity toward the aforementioned resolutions. [...] Read more.

A transition from conventional centralized to hybrid decentralized systems has been increasingly advised recently due to their capability to enhance the resilience and sustainability of urban water supply systems. Reusing treated wastewater for non-potable purposes is a promising opportunity toward the aforementioned resolutions. In this study, we present two optimization models for integrating reusing systems into existing sewerage systems to bridge the supply–demand gap in an existing water supply system. In Model-1, the supply–demand gap is bridged by introducing on-site graywater treatment and reuse, and in Model-2, the gap is bridged by decentralized wastewater treatment and reuse. The applicability of the proposed models is evaluated using two test cases: one a proof-of-concept hypothetical network and the other a near realistic network based on the sewerage network in Chennai, India. The results show that the proposed models outperform the existing approaches by achieving more than a 20% reduction in the cost of procuring water and more than a 36% reduction in the demand for freshwater through the implementation of local on-site graywater reuse for both test cases. These numbers are about 12% and 34% respectively for the implementation of decentralized wastewater treatment and reuse. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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15 pages, 1925 KiB

Open AccessFeature PaperArticle

Revealing the Challenges of Smart Rainwater Harvesting for Integrated and Digital Resilience of Urban Water Infrastructure

by Martin Oberascher, Aun Dastgir, Jiada Li, Sina Hesarkazzazi, Mohsen Hajibabaei, Wolfgang Rauch and Robert Sitzenfrei

Water 2021, 13(14), 1902; https://doi.org/10.3390/w13141902 - 09 Jul 2021

Cited by 11 | Viewed by 3858

Abstract

Smart rainwater harvesting (RWH) systems can automatically release stormwater prior to rainfall events to increase detention capacity on a household level. However, impacts and benefits of a widespread implementation of these systems are often unknown. This works aims to investigate the effect of [...] Read more.

Smart rainwater harvesting (RWH) systems can automatically release stormwater prior to rainfall events to increase detention capacity on a household level. However, impacts and benefits of a widespread implementation of these systems are often unknown. This works aims to investigate the effect of a large-scale implementation of smart RWH systems on urban resilience by hypothetically retrofitting an Alpine municipality with smart rain barrels. Smart RWH systems represent dynamic systems, and therefore, the interaction between the coupled systems RWH units, an urban drainage network (UDN) and digital infrastructure is critical for evaluating resilience against system failures. In particular, digital parameters (e.g., accuracy of weather forecasts, or reliability of data communication) can differ from an ideal performance. Therefore, different digital parameters are varied to determine the range of uncertainties associated with smart RWH systems. As the results demonstrate, smart RWH systems can further increase integrated system resilience but require a coordinated integration into the overall system. Additionally, sufficient consideration of digital uncertainties is of great importance for smart water systems, as uncertainties can reduce/eliminate gained performance improvements. Moreover, a long-term simulation should be applied to investigate resilience with digital applications to reduce dependence on boundary conditions and rainfall patterns. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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19 pages, 45646 KiB

Open AccessArticle

Toward Decentralised Sanitary Sewage Collection Systems: A Multiobjective Approach for Cost-Effective and Resilient Designs

by Arezoo Zahediasl, Amin E. Bakhshipour, Ulrich Dittmer and Ali Haghighi

Water 2021, 13(14), 1886; https://doi.org/10.3390/w13141886 - 07 Jul 2021

Cited by 8 | Viewed by 2741

Abstract

In recent years, the concept of a centralized drainage system that connect an entire city to one single treatment plant is increasingly being questioned in terms of the costs, reliability, and environmental impacts. This study introduces an optimization approach based on decentralization in [...] Read more.

In recent years, the concept of a centralized drainage system that connect an entire city to one single treatment plant is increasingly being questioned in terms of the costs, reliability, and environmental impacts. This study introduces an optimization approach based on decentralization in order to develop a cost-effective and sustainable sewage collection system. For this purpose, a new algorithm based on the growing spanning tree algorithm is developed for decentralized layout generation and treatment plant allocation. The trade-off between construction and operation costs, resilience, and the degree of centralization is a multiobjective problem that consists of two subproblems: the layout of the networks and the hydraulic design. The innovative characteristics of the proposed framework are that layout and hydraulic designs are solved simultaneously, three objectives are optimized together, and the entire problem solving process is self-adaptive. The model is then applied to a real case study. The results show that finding an optimum degree of centralization could reduce not only the network’s costs by 17.3%, but could also increase its structural resilience significantly compared to fully centralized networks. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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21 pages, 6318 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Exploring the Spatial Impact of Green Infrastructure on Urban Drainage Resilience

by Mayra Rodriguez, Guangtao Fu, David Butler, Zhiguo Yuan and Keshab Sharma

Water 2021, 13(13), 1789; https://doi.org/10.3390/w13131789 - 28 Jun 2021

Cited by 14 | Viewed by 3943

Abstract

This paper explores the spatial impact of green infrastructure (GI) location on the resilience of urban drainage systems by the application of exploratory spatial data analysis (ESDA). A framework that integrates resilience assessment, location sensitivity analysis and ESDA is presented and applied to [...] Read more.

This paper explores the spatial impact of green infrastructure (GI) location on the resilience of urban drainage systems by the application of exploratory spatial data analysis (ESDA). A framework that integrates resilience assessment, location sensitivity analysis and ESDA is presented and applied to an urban catchment in the United Kingdom. Three types of GI, namely a bioretention cell, permeable pavement, and green roof, are evaluated separately and simultaneously. Resilience is assessed using stress-strain tests, which measure the system performance based on the magnitude and duration of sewer flooding and combined sewer overflows. Based on the results of a location sensitivity analysis, ESDA is applied to determine if there is spatial autocorrelation, spatial clusters, and spatial outliers. Results show a stronger spatial dependency using sewer flooding indicators. Different GI measures present differences in spatial autocorrelation and spatial cluster results, highlighting the differences in their underlying mechanisms. The finding of conflicting spatial clusters indicates that there are trade-offs in the placement of GI in certain locations. The proposed framework can be used as a tool for GI spatial planning, helping in the development of a systematic approach for resilience-performance orientated GI design and planning. Full article

(This article belongs to the Special Issue Resilience of Interdependent Urban Water Systems)

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