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Publications

  • Koundouri P, Alamanos A, Papaioannou G, Markogianni V, Varlas G, Basheer M, Nagkoulis N, Plataniotis A, Wise RM, Xenarios S, Nisiforou O, Papadopoulos A, Dimitriou E. (2025). Post-fire flood hazards: Integrated modelling, protection measures, and economic implications (SDSN Global Climate Hub – AE4RIA Report, August 2025)

    Climate change-induced wildfires are increasingly prevalent, particularly during summer periods, with evident consequences in multiple regions worldwide. Wildfires affect and change the condition, functionality, and ecosystem services of the burned sites. Altered hydrologic processes make burnt areas more flood-prone. However, the actual effects of wildfires to flooding, the post-fire protection measures and their economic implications remain still overlooked issues. In this report, we cover these gaps in a multi-disciplinary way. More specifically: PART A: We present a novel, integrated and interdisciplinary computational framework that we have developed for the accurate modelling of post-fire flash-flood events. The 2019 post-fire flood in Kineta, Central Greece is used as a case study-example. The proposed approach assesses the fire impacts (burn extent and severity) with Remote Sensing techniques; ‘recreates’ real storms using the atmospheric model WRF-ARW; simulates the flood using the 2D HEC-RAS hydraulic-hydrodynamic model; and validates the results with remote sensing analysis on the flood extent. We detail the linking of those models, step-by-step, for the first time. We build upon the findings by reviewing, selecting and designing the most appropriate Post-fire Erosion and Flood-protection Treatments (PEFTs), and represent them within a Geographic Information System (GIS), which allows their incorporation to the HEC-RAS hydraulic model. The flood event is simulated under three scenarios: prefire; post-fire (real case, happened in November 2019), and post-fire with the PEFTs protection. Thus, for the first time, we reveal the effects of the fire on flooding (~25%), as well as the effectiveness of the suggested measures to mitigate the flood (completely offsetting the fire’s effect). In order to assess the economic implications of the potential flood protection interventions, we present also a detailed estimation of the: i) Costs of the proposed PEFTs, ii) The flood damage direct costs, which were estimated by a semi-automated AI-based approach using image segmentation and human-checks. The comparison of the costs reveals that protection could have cost just 13.6% of the direct damages. Part B: Drawing from the inaction and poor protection of our real case study, we explore the governance gaps. We performed a knowledge-transfer exercise from similar cases in Australia (climate and governance similarities), based on the VRK (Values-Rules-Knowledge) framework. We provide a detailed stakeholder engagement roadmap targeting changes in anachronistic perceptions about the extreme phenomena, the understanding and application of solutions, and their communication as necessary, multi-benefit and cost-effective measures. These findings are applicable to other case studies, too. Part C: For the facilitation of similar analyses nation-wide, we provide a national Greek inventory of design storms based on the official IDF (intensity-duration-frequency) Curves. For this purpose, we developed a novel tool called Catchment2Storm that provides customized design storms (return periods, durations, time intervals) using just the desired catchment’s location. We comment on the results of its Greek-wide application, highlighting the need for localized design considerations in critical sites such as urban centers, ports, and agricultural areas. 6 Finally, we synthesize all the above into a concrete, agenda-setting list of policy recommendations to foster resilience to combined hazards.

    SDSN Global Climate Hub Report
  • Paul Stahlhofen, Dennis Zanutto, André Artelt, Luca Hermes, Alissa Müller, Barbara Hammer, Dragan Savic "Reinforcement Learning for Dynamic Pump Scheduling under Demand Uncertainty". CCWI 2025

    Reliable and cost-efficient scheduling of pumps is an important task in the daily operations of urban water distribution networks (WDNs). In this work, we address the scheduling of variable-speed pumps using reinforcement learning (RL), which allows network controls to adapt to changes in demand in real-time after a data-driven training phase. Previous contributions have shown the general suitability of RL for control tasks in WDNs [1], [2]. However, most of them assume deterministically known demand patterns (cf. [1]) or consider uncertainty only for valve control (cf. [2]). As RL algorithms can handle uncertain environments, we explore their potential for dynamic scheduling of the network’s pumps under uncertain demand patterns. Our optimisation goal is to train a policy that complies with upper and lower pressure bounds at all nodes in the network while minimising the cost of pumping. To this end, we make use of the Soft Actor-Critic algorithm (SAC) [3]. Data for training and testing is collected using the EPANET simulator for two benchmark networks (Net1 and Anytown) with uncertainties applied to various network parameters. In all setups, the controller is trained without nodal demand information. Our study shows promising results for a pump scheduler that can reduce energy cost by a significant amount while complying with pressure bounds even for unseen scenarios.

    https://doi.org/10.15131/shef.data.29921117.v1
  • André Artelt, Katharina Giese, Stelios G. Vrachimis, Demetris Eliades, Marios M. Polycarpou, Barbara Hammer "The WaterBenchmarkHub: A Platform for Benchmarks in Water Distribution Networks". CCWI 2025

    Publicly accessible and user-friendly benchmarks are crucial for advancing and accelerating research in smart water systems and supporting reproducible studies. Benchmark resources related to Water Distribution Networks (WDNs) are difficult to access, as they are not consolidated within a centralized, standardized interface that could enhance their accessibility, usability, and relevance for researchers. Currently, they are dispersed across various sources, often poorly labelled and lacking clear guidance on their intended use or the research problems they address. In this work, we introduce the WaterBenchmarkHub platform, an open-source and community-driven platform, designed to offer a standardized interface for benchmarking resources. The WaterBenchmarkHub consists of a web interface for browsing the benchmark resources, and a Python package for easy access of those benchmark resources in Python. This project aims to enhance accessibility for a broader range of researchers and ultimately promote and strengthen reproducible research within the community.

    https://doi.org/10.15131/shef.data.29921051.v1
  • Luca Hermes, André Artelt, Stelios G. Vrachimis, Marios M. Polycarpou, Barbara Hammer "A Benchmark for Physics-informed Machine Learning of Chlorine Concentration States in Water Distribution Networks". SN COMPUT. SCI. 6, 522 (2025)

    Ensuring high-quality drinking water is a critical responsibility of water utilities, with chlorine being the main disinfectant typically used. Accurate estimation of chlorine concentrations in the dynamic environment of water distribution networks (WDNs) is essential to ensure safe water supply. This work introduces a comprehensive and carefully created benchmark for training and evaluation of chlorine concentration estimation methodologies in WDNs. The benchmark includes a diverse dataset of 18,000 scenarios of the widely studied ‘Hanoi’, ‘Net1’, and the more recent and complex ‘CY-DBP’ water networks, featuring various chlorine injection patterns to capture diverse physical dynamics. To provide baseline evaluations, we propose and evaluate two neural surrogate models for chlorine state estimation: a physics-informed Graph Neural Network (GNN) and a physics-guided Recurrent Neural Network (RNN).

    https://doi.org/10.1007/s42979-025-04008-y
  • Paraskevopoulos, S.; Vrachimis, S.G.; Kyriakou, M.S.; Blokker, M.; Smeets, P.; Eliades, D.G.; Polycarpou, M.; Medema, G. An Innovative Model-Based Methodology for Rapid Response to Drinking Water Contamination Events. Eng. Proc. 2024, 69, 45.

    In a desktop exercise, a water utility’s emergency response to suspected wastewater contamination in a drinking water network was compared with a model-based approach using PathoINVEST. This tool simulates contamination scenarios and assists with locating the source of contamination using sampling results.

    https://doi.org/10.3390/engproc2024069045
  • Sotirios Paraskevopoulos, Stelios Vrachimis, Marios Kyriakou, Demetrios G. Eliades, Patrick Smeets, Marios Polycarpou, Gertjan Medema, Modeling the health impact of wastewater contamination events in drinking water networks, Journal of Cleaner Production, Volume 479, 2024.

    Pathogen intrusion in drinking water systems can pose severe health risks. To better prepare in planning and responding to such events, computational models that capture the intrusion and health impact dynamics are needed. This study presents a novel benchmark testbed that integrates current knowledge on pathogen transport and fate in chlorinated systems and can assess infection risk from contamination events.

    https://doi.org/10.1016/j.jclepro.2024.143997
  • Qingkai Meng, Stelios Vrachimis, Marios M. Polycarpou, Fault-tolerant Safe Control for Water Networks: An Interconnected Switched System Approach., IFAC-PapersOnLine, Volume 58, Issue 4, 2024, Pages 294-299.

    This paper investigates the fault-tolerant safe control problem in water network systems in the presence of process and actuator faults.

    https://doi.org/10.1016/j.ifacol.2024.07.233
  • Z. Gao, Y. Song and M. M. Polycarpou, "Adaptive Security Control Using Output Only for Quantized Nonlinear Systems Under Irregularly Intermittent DoS Attacks," in IEEE Transactions on Cybernetics, vol. 54, no. 11, pp. 6755-6766, Nov. 2024.

    Quantized signal-driven control for nonlinear systems is of special interest in practice. However, it is nontrivial in the presence of mismatched uncertainties and intermittent denial of service (DoS) attacks. The underlying problem becomes even more complicated when both the input and output signals are attacked, rendering the state variables and the input signal inaccessible or unavailable for the control design. Only the quantized (and thus nondifferentiable) output signal is available in the absence of attack, making regular backstepping design inapplicable. This article introduces a novel adaptive output feedback control method to tackle the aforementioned challenges.

    https://doi.org/10.1109/TCYB.2024.3438288
  • Qingkai Meng, Andreas Kasis, Hao Yang, Marios M. Polycarpou, Secure state estimation of networked switched systems under denial-of-service attacks, European Journal of Control, Volume 80, Part A, 2024.

    This paper studies the problem of secure state estimation of networked switched systems in the presence of denial-of-service (DoS) attacks, as well as disturbances and measurement noise. Firstly, a state transformation rule is designed to partition the original system into two subsystems, facilitating the design of discrete and continuous state observers

    https://doi.org/10.1016/j.ejcon.2024.101037
  • Tirandaz, H., Keliris, C., & Polycarpou, M. (2024). Actuator fault detection and isolation in a class of nonlinear interconnected systems. International Journal of Control, 97(12), 2914–2934.

    In this paper, the problem of actuator fault detection and isolation is investigated for a class of nonlinear interconnected large-scale systems with modelling uncertainty and measurement noise, where each subsystem can have multiple inputs and multiple outputs (MIMO). The main contribution of this work is the derivation of a scheme that is able to diagnose single or multiple actuator faults in one or multiple subsystems.

    https://doi.org/10.1080/00207179.2024.2310606
  • Hamed Tirandaz, Christodoulos Keliris, Marios M. Polycarpou, Actuator and sensor fault isolation in a class of nonlinear dynamical systems, Journal of Automation and Intelligence, Volume 3, Issue 2, 2024, Pages 57-72.

    Fault isolation in dynamical systems is a challenging task due to modeling uncertainty and measurement noise, interactive effects of multiple faults and fault propagation. This paper proposes a unified approach for isolation of multiple actuator or sensor faults in a class of nonlinear uncertain dynamical systems. Actuator and sensor fault isolation are accomplished in two independent modules, that monitor the system and are able to isolate the potential faulty actuator(s) or sensor(s).

    https://doi.org/10.1016/j.jai.2024.03.001
  • André Artelt and Marios S. Kyriakou and Stelios G. Vrachimis and Demetrios G. Eliades and Barbara Hammer and Marios M. Polycarpou, (2024) "EPyT-Flow: A Toolkit for Generating Water Distribution Network Data"

    EPyT-Flow: A Toolkit for Generating Water Distribution Network Data.

    https://doi.org/10.21105/joss.07104
  • Valerie Vaquet, Jonas Vaquet, Fabian Hinder, Kleanthis Malialis, Christos Panayiotou, Marios Polycarpou, Barbara Hammer, (2024) “Self-Supervised Learning from Incrementally Drifting Data Streams”

    Supervised online learning relies on the assumption that ground truth information is available for model updates at each time step. As this is not realistic in every setting, alternatives such as active online learning, or online learning with verification latency have been proposed. In this work, we assume that no label information is available after intitial training. We argue that provided we can characterize the expected concept drift as incremental drift, we can rely on a self-labeling strategy to keep updated models. We derive a k-NN-based self-labeling online learner implementing the presented self-supervised scheme and experimentally show that this is an option for learning from incrementally drifting data streams in the absence of label information.

    https://doi.org/10.14428/esann/2024.ES2024-49
  • Brinkrolf, J., Vaquet, V., Hinder, F., and Hammer, B., (2024) “Causes of Rejects in Prototype-based Classification Aleatoric vs. Epistemic Uncertainty”

    Prototype-based methods constitute a robust and transparent family of machine-learning models. To increase robustness in real-world applications, they are frequently coupled with reject options. While the state-of-the-art method, relative similarity, couples the rejection of samples with high aleatoric and epistemic uncertainty, the technique lacks transparency, i.e., an explanation of why a sample has been rejected. In this work, we analyze the relative similarity analytically and derive an explanation scheme for reject options in prototype-based classification.

    https://doi.org/10.14428/esann/2024.ES2024-156
  • Hinder, F., Vaquet, V. and Hammer, B., (2024) “On the Fine Structure of Drifting Features”

    Feature selection is one of the most relevant preprocessing and analysis techniques in machine learning, allowing for increases in model performance and knowledge discovery. In online setups, both can be affected by concept drift, i.e., changes of the underlying distribution. Recently, an adaption of classical feature relevance approaches to drift detection was introduced. While the method increases detection performance significantly, there is only little discussion on the explanatory aspects. In this work, we focus on understanding the structure of the ongoing drift by transferring the concept of strongly and weakly relevant features to it. We empirically evaluate our methodology using graphical models.

    https://doi.org/10.14428/esann/2024.ES2024-89
  • Janine Strotherm​, Inaam Ashraf, Barbara Hammer, (2024) “Fairness-enhancing classification methods for non-binary sensitive features—How to fairly detect leakages in water distribution systems”

    Especially if artificial intelligence (AI)-supported decisions affect the society, the fairness of such AI-based methodologies constitutes an important area of research. In this contribution, we investigate the applications of AI to the socioeconomically relevant infrastructure of water distribution systems (WDSs). We propose an appropriate definition of protected groups in WDSs and generalized definitions of group fairness, applicable even to multiple non-binary sensitive features, that provably coincide with existing definitions for a single binary sensitive feature. We demonstrate that typical methods for the detection of leakages in WDSs are unfair in this sense. Further, we thus propose a general fairness-enhancing framework as an extension of the specific leakage detection pipeline, but also for an arbitrary learning scheme, to increase the fairness of the AI-based algorithm. Finally, we evaluate and compare several specific instantiations of this framework on a toy and on a realistic WDS to show their utility.

    https://doi.org/10.7717/peerj-cs.2317
  • Janine Strotherm, Alissa Müller, Barbara Hammer, Benjamin Paaßen, (2024) “Fairness in KI-Systemen”

    Je mehr KI-gestützte Entscheidungen das Leben von Menschen betreffen, desto wichtiger ist die Fairness solcher Entscheidungen. Dieser Beitrag gibt eine Einführung in die Forschung zu Fairness in KI-Systemen, erklärt die wesentlichen Fairness-Definitionen und Strategien zur Erreichung von Fairness anhand konkreter Beispiele und ordnet die Fairness-Forschung in den europäischen Kontext ein. Weder in der europäischen Gesetzgebung noch in der KI-Forschung kommt es dabei zu einem Konsens, wie Fairness zu definieren und zu erreichen ist. Stattdessen muss für jedes System eine differenzierte und kontextabhängige Betrachtung von möglichen unfairen Ergebnissen und deren Konsequenzen erfolgen. Dieser Beitrag kann dabei unterstützen und richtet sich an ein interdisziplinäres Publikum, indem auf mathematische Formulierungen verzichtet wird und stattdessen Visualisierungen und Beispiele genutzt werden.

    https://doi.org/10.1007/978-3-658-43816-6_9
  • Valerie Vaquet, Fabian Hinder, Jonas Vaquet, Kathrin Lammers, Lars Quakernack, Barbara Hammer, (2024) “Localizing Anomalies in Critical Infrastructure using Model-Based Drift Explanations”

    Facing climate change, the already limited availability of drinking water will decrease in the future, rendering drinking water an increasingly scarce resource. Considerable amounts of it are lost through leakages in water transportation and distribution networks. Thus, anomaly detection and localization, in particular for leakages, are crucial but challenging tasks due to the complex interactions and changing demands in water distribution networks. In this work, we conceptually analyze the effects of anomalies on the dynamics of critical infrastructure systems by modeling them with Bayesian networks. We then discuss how the problem is connected to and can be considered through the lens of concept drift. This analysis yields our proposal to leverage model-based drift explanations as a tool for localizing anomalies given limited information about the network. The methodology is experimentally evaluated using realistic benchmark scenarios. To showcase that our methodology applies to critical infrastructure more generally, in addition to considering leakages and sensor faults in water systems, we investigate the suitability of the derived technique to localize sensor faults in power systems.

    https://doi.org/10.1109/IJCNN60899.2024.10651472
  • Valerie Vaquet, Fabian Hinder, André Artelt, Inaam Ashraf, Janine Strotherm, Jonas Vaquet, Johannes Brinkrolf & Barbara Hammer, (2024) “Challenges, Methods, Data–A Survey of Machine Learning in Water Distribution Networks”

    Research on methods for planning and controlling water distribution networks gains increasing relevance as the availability of drinking water will decrease as a consequence of climate change. So far, the majority of approaches is based on hydraulics and engineering expertise. However, with the increasing availability of sensors, machine learning techniques constitute a promising tool. This work presents the main tasks in water distribution networks, discusses how they relate to machine learning and analyses how the particularities of the domain pose challenges to and can be leveraged by machine learning approaches. Besides, it provides a technical toolkit by presenting evaluation benchmarks and a structured survey of the exemplary task of leakage detection and localization.

    https://doi.org/10.1007/978-3-031-72356-8_11
  • Hinder, F., Vaquet, V. and Hammer, B., (2024) “Feature-based analyses of concept drift”

    Feature selection is one of the most relevant preprocessing and analysis techniques in machine learning. It can dramatically increase the performance of learning algorithms and at the same time provide relevant information on the data. In the scenario of online and stream learning, concept drift, i.e., changes of the underlying distribution over time, can cause significant problems for learning models and data analysis. While there do exist feature selection methods for online learning, none of the methods targets feature selection for drift detection, i.e., the challenge to increase the performance of drift detectors by analyzing the drift rather than increasing model accuracy. However, this challenge is particularly relevant for common unsupervised scenarios. In this work, we study feature selection for drift detection and drift monitoring. We develop a formal definition for a feature-wise notion of drift that allows semantic interpretation. Besides, we derive an efficient algorithm by reducing the problem to classical feature selection and analyze the applicability of our approach to feature selection for drift detection on a theoretical level. Finally, we empirically show the relevance of our considerations on several benchmarks.

    https://doi.org/10.1016/j.neucom.2024.127968
  • Hinder, F., Vaquet, V. and Hammer, B., (2024) “One or two things we know about concept drift—a survey on monitoring in evolving environments. Part A: detecting concept drift”

    The world surrounding us is subject to constant change. These changes, frequently described as concept drift, influence many industrial and technical processes. As they can lead to malfunctions and other anomalous behavior, which may be safety-critical in many scenarios, detecting and analyzing concept drift is crucial. In this study, we provide a literature review focusing on concept drift in unsupervised data streams. While many surveys focus on supervised data streams, so far, there is no work reviewing the unsupervised setting. However, this setting is of particular relevance for monitoring and anomaly detection which are directly applicable to many tasks and challenges in engineering. This survey provides a taxonomy of existing work on unsupervised drift detection. In addition to providing a comprehensive literature review, it offers precise mathematical definitions of the considered problems and contains standardized experiments on parametric artificial datasets allowing for a direct comparison of different detection strategies. Thus, the suitability of different schemes can be analyzed systematically, and guidelines for their usage in real-world scenarios can be provided.

    https://doi.org/10.3389/frai.2024.1330257
  • Hinder, F., Vaquet, V. and Hammer, B., (2024) “One or two things we know about concept drift—a survey on monitoring in evolving environments. Part B: locating and explaining concept drift”

    In an increasing number of industrial and technical processes, machine learning-based systems are being entrusted with supervision tasks. While they have been successfully utilized in many application areas, they frequently are not able to generalize to changes in the observed data, which environmental changes or degrading sensors might cause. These changes, commonly referred to as concept drift can trigger malfunctions in the used solutions which are safety-critical in many cases. Thus, detecting and analyzing concept drift is a crucial step when building reliable and robust machine learning-driven solutions. In this work, we consider the setting of unsupervised data streams which is highly relevant for different monitoring and anomaly detection scenarios. In particular, we focus on the tasks of localizing and explaining concept drift which are crucial to enable human operators to take appropriate action. Next to providing precise mathematical definitions of the problem of concept drift localization, we survey the body of literature on this topic. By performing standardized experiments on parametric artificial datasets we provide a direct comparison of different strategies. Thereby, we can systematically analyze the properties of different schemes and suggest first guidelines for practical applications. Finally, we explore the emerging topic of explaining concept drift.

    https://doi.org/10.3389/frai.2024.1330258
  • Artelt, A., Kyriakou, M. S., Vrachimis, S. G., Eliades, D. G., Hammer, B., & Polycarpou, M. M. (2024) “A Toolbox for Supporting Research on AI in Water Distribution Networks”, Workshop on Artificial Intelligence for Critical Infrastructure (AI4CI 2024) @ IJCAI'24 , Jeju Island, South Korea

    Drinking water is a vital resource for humanity, and thus, Water Distribution Networks (WDNs) are considered critical infrastructures in modern societies. The operation of WDNs is subject to diverse challenges such as water leakages and contamination, cyber/physical attacks, high energy consumption during pump operation, etc. With model-based methods reaching their limits due to various uncertainty sources, AI methods offer promising solutions to those challenges. In this work, we introduce a Python toolbox for complex scenario modeling \& generation such that AI researchers can easily access challenging problems from the drinking water domain. Besides providing a high-level interface for the easy generation of hydraulic and water quality scenario data, it also provides easy access to popular event detection benchmarks and an environment for developing control algorithms.

    https://doi.org/10.48550/arXiv.2406.02078
  • Hinder, F., Vaquet, V. and Hammer, B., (2024) “A Remark on Concept Drift for Dependent Data”

    Concept drift, i.e., the change of the data generating distribution, can render machine learning models inaccurate. Several works address the phenomenon of concept drift in the streaming context usually assuming that consecutive data points are independent of each other. To generalize to dependent data, many authors link the notion of concept drift to time series. In this work, we show that the temporal dependencies are strongly influencing the sampling process. Thus, the used definitions need major modifications. In particular, we show that the notion of stationarity is not suited for this setup and discuss an alternative we refer to as consistency. We demonstrate that consistency better describes the observable learning behavior in numerical experiments.

    https://doi.org/10.1007/978-3-031-58547-0_7
  • Vaquet, V.; Hinder, F. and Hammer, B., (2024) “Investigating the Suitability of Concept Drift Detection for Detecting Leakages in Water Distribution Networks”

    Leakages are a major risk in water distribution networks as they cause water loss and increase contamination risks. Leakage detection is a difficult task due to the complex dynamics of water distribution networks. In particular, small leakages are hard to detect. From a machine-learning perspective, leakages can be modeled as concept drift. Thus, a wide variety of drift detection schemes seems to be a suitable choice for detecting leakages. In this work, we explore the potential of model-loss-based and distribution-based drift detection methods to tackle leakage detection. We additionally discuss the issue of temporal dependencies in the data and propose a way to cope with it when applying distribution-based detection. We evaluate different methods systematically for leakages of different sizes and detection times. Additionally, we propose a first drift-detection-based technique for localizing leakages.

    https://doi.org/10.5220/0012361200003654
  • Ashraf, I., Strotherm, J., Hermes, L., & Hammer, B., (2024) “Physics-Informed Graph Neural Networks for Water Distribution Systems”

    Water distribution systems (WDS) are an integral part of critical infrastructure which is pivotal to urban development. As 70% of the world's population will likely live in urban environments in 2050, efficient simulation and planning tools for WDS play a crucial role in reaching UN's sustainable developmental goal (SDG) 6 - "Clean water and sanitation for all". In this realm, we propose a novel and efficient machine learning emulator, more precisely, a physics-informed deep learning (DL) model, for hydraulic state estimation in WDS. Using a recursive approach, our model only needs a few graph convolutional neural network (GCN) layers and employs an innovative algorithm based on message passing. Unlike conventional machine learning tasks, the model uses hydraulic principles to infer two additional hydraulic state features in the process of reconstructing the available ground truth feature in an unsupervised manner. To the best of our knowledge, this is the first DL approach to emulate the popular hydraulic simulator EPANET, utilizing no additional information. Like most DL models and unlike the hydraulic simulator, our model demonstrates vastly faster emulation times that do not increase drastically with the size of the WDS. Moreover, we achieve high accuracy on the ground truth and very similar results compared to the hydraulic simulator as demonstrated through experiments on five real-world WDS datasets.

    https://doi.org/10.1609/aaai.v38i20.30192
  • L. Tsiami, C. Makropoulos, and D. Savić, “Reinforcement Learning for Adaptive Water Distribution Network Planning: Exploring its Feasibility and Potential,” in Proceedings of the 19th International Computing and Control for the Water Industry Conference, 2023.

    Long-term water network planning methods need to be adaptive under deep uncertainty.

    Reinforcement learning (RL) is a promising approach for decision-making under uncertainty.

    We propose the application of reinforcement learning for the design of water networks.

    Results show that an RL agent can find feasible solutions to deterministic problems.

    This is a first step towards the development of more adaptive planning approaches in the field.

    https://virtual.oxfordabstracts.com/#/event/3937/submission/54
  • Kleanthis Malialis, Dimitris Papatheodoulou, Stylianos Filippou, Christos G. Panayiotou, Marios M. Polycarpou (2023), "Data Augmentation On-the-fly and Active Learning in Data Stream Classification"

    There is an emerging need for predictive models to be trained on-the-fly, since in numerous machine learning applications data are arriving in an online fashion. A critical challenge encountered is that of limited availability of ground truth information (e.g., labels in classification tasks) as new data are observed one-by-one online, while another significant challenge is that of class imbalance. This work introduces the novel Augmented Queues method, which addresses the dual-problem by combining in a synergistic manner online active learning, data augmentation, and a multi-queue memory to maintain separate and balanced queues for each class. We perform an extensive experimental study using image and time-series augmentations, in which we examine the roles of the active learning budget, memory size, imbalance level, and neural network type. We demonstrate two major advantages of Augmented Queues. First, it does not reserve additional memory space as the generation of synthetic data occurs only at training times. Second, learning models have access to more labelled data without the need to increase the active learning budget and / or the original memory size. Learning on-the-fly poses major challenges which, typically, hinder the deployment of learning models. Augmented Queues significantly improves the performance in terms of learning quality and speed. Our code is made publicly available.

    https://zenodo.org/records/7659977
  • Kleanthis Malialis, Manuel Roveri, Cesare Alippi, Christos G. Panayiotou, Marios M. Polycarpou (2022), "A Hybrid Active-Passive Approach to Imbalanced Nonstationary Data Stream Classification"

    In real-world applications, the process generating the data might suffer from nonstationary effects (e.g., due to seasonality, faults affecting sensors or actuators, and changes in the users' behaviour). These changes, often called concept drift, might induce severe (potentially catastrophic) impacts on trained learning models that become obsolete over time, and inadequate to solve the task at hand. Learning in presence of concept drift aims at designing machine and deep learning models that are able to track and adapt to concept drift. Typically, techniques to handle concept drift are either active or passive, and traditionally, these have been considered to be mutually exclusive. Active techniques use an explicit drift detection mechanism, and re-train the learning algorithm when concept drift is detected. Passive techniques use an implicit method to deal with drift, and continually update the model using incremental learning. Differently from what present in the literature, we propose a hybrid alternative which merges the two approaches, hence, leveraging on their advantages. The proposed method called Hybrid-Adaptive REBAlancing (HAREBA) significantly outperforms strong baselines and state-of-the-art methods in terms of learning quality and speed; we experiment how it is effective under severe class imbalance levels too.

    https://ieeexplore.ieee.org/document/10022140
  • Jin Li, Kleanthis Malialis, Marios M. Polycarpou (2023), "Autoencoder-based Anomaly Detection in Streaming Data with Incremental Learning and Concept Drift Adaptation"

    In our digital universe nowadays, enormous amount of data are produced in a streaming manner in a variety of application areas. These data are often unlabelled. In this case, identifying infrequent events, such as anomalies, poses a great challenge. This problem becomes even more difficult in non-stationary environments, which can cause deterioration of the predictive performance of a model. To address the above challenges, the paper proposes an autoencoder-based incremen-tal learning method with drift detection (strAEm++DD). Our proposed method strAEm++DD leverages on the advantages of both incremental learning and drift detection. We conduct an experimental study using real-world and synthetic datasets with severe or extreme class imbalance, and provide an empirical analysis of strAEm++DD. We further conduct a comparative study, showing that the proposed method significantly outper-forms existing baseline and advanced methods.

    https://ieeexplore.ieee.org/document/10191328
  • Vrachimis, S. G., Eliades, D. G., & Polycarpou, M. M. (2024). "Disinfection scheduling in water distribution networks considering input time-delay uncertainty."

    A significant challenge when attempting to regulate the spatial-temporal concentration of a disinfectant in a water distribution network is the large and uncertain delay between the time that the chemical is injected at the input node and the time that the concentration is measured at the monitoring output nodes. Uncertain time delays are due to varying water flows, which depend mainly on consumer water demands. Existing approaches cannot guarantee that the concentration of the disinfectant will remain within a specified range at the output, even though bounds on time-delay uncertainty may be known. In this work, given bounded water-flow uncertainty, we use the input–output modeling approach to develop a disinfectant scheduling methodology that guarantees a bounded output disinfectant concentration. The proposed methodology creates an input–output model uncertainty characterization by utilizing estimated bounds on water-quality states using the backtracking approach. An optimization problem is formulated and solved to find an input schedule that keeps the disinfectant concentration within predefined bounds for a specified time horizon. Simulation results in two case studies where water demands varied between ±20% of their nominal value show that the proposed scheduler is able to avoid lower bound violations of disinfectant concentration.

    https://iwaponline.com/jh/article/26/2/386/99925/Disinfection-scheduling-in-water-distribution
  • Anand, V., Pramov, A., Vrachimis, S., Polycarpou, M., & Dovrolis, C. (2023). "Incremental Versus Optimal Design of Water Distribution Networks-The Case of Tree Topologies".

    This study delves into the differences between incremental and optimized network design, with a focus on tree-shaped water distribution networks (WDNs). The study evaluates the cost overhead of incremental design under two distinct expansion models: random and gradual. Our findings reveal that while incremental design does incur a cost overhead, this overhead does not increase significantly as the network expands, especially under gradual expansion. We also evaluate the cost overhead for the two tree-shaped WDNs of a city in Cyprus. The paper underscores the need to consider the evolution of infrastructure networks, answering key questions about cost overhead, scalability, and design efficacy.

    https://link.springer.com/chapter/10.1007/978-3-031-53503-1_21
  • Eliades, D. G., Vrachimis, S. G., Moghaddam, A., Tzortzis, I., & Polycarpou, M. M. (2023). "Contamination event diagnosis in drinking water networks: A review"

    Water distribution systems are susceptible to contamination events, which can occur due to naturally occurring events, accidents or even malicious attacks. When a contamination event occurs, dangerous substances infiltrating the network may be consumed thereby deteriorating the consumers’ health and possibly affecting the economy. Advances in sensor and actuator technologies are enabling water networks to become smarter and more resilient to these types of events. This paper provides a broad review of the theoretical, modeling, and computational developments in the area of contamination event diagnosis for water distribution systems. Research is segmented into three main tasks, summarized as “Preparedness”, “Event Detection and Isolation” and “Emergency Event Management”. The key research topics from each task are described within a unified systems-theoretic mathematical framework, and their open challenges are discussed.

    https://www.sciencedirect.com/science/article/pii/S1367578823000159
  • Minaei, A., Hajibabaei, M., Savic, D., Creaco, E. and Sitzenfrei, R. (2023). "Optimal rehabilitation planning for aged water distribution mains considering cascading failures of interdependent infrastructure systems".

    Water distribution networks (WDNs) with other infrastructures constitute a complex and interdependent multi-utility system. Considering interdependencies between WDNs and other urban infrastructures, this work proposes WDN intervention planning using a dynamic multi-utility approach to tackle the challenges of pressure deficits and cascading failures by the decoupling of different infrastructure systems. For this purpose, the study develops reliability indices representing the hydraulic and decoupled statuses of WDNs with neighbor infrastructures; the hydraulic reliability represents the robustness of the network against the water pressure deficit, and decoupling reliability represents the extent to which WDN elements are decoupled from other assets elements. A multi-objective optimization algorithm is employed to develop rehabilitation strategies by introducing three approaches for WDN upgrade following a phased design and construction method. Evaluating intervention plans based on construction cost, reliability and cascade effects shows that, under budget limitation conditions, decoupling a WDN could significantly save the cascade cost such that 1% improvement in the decoupling reliability brings about 157.42 billion Rials cascade cost saving to asset managers. On the other hand, the decoupled network is weak against hydraulic reliability, which could make it by far less resilient network than the coupled network with around 75% hydraulic reliability difference.

    https://iwaponline.com/jh/article/25/5/2084/97296/Optimal-rehabilitation-planning-for-aged-water
  • Phoebe Koundouri, Barbara Hammer, Ulrike Kuhl, Alina Velias, "Behavioral Economics and Neuroeconomics of Environmental Values"

    Identifying mechanisms of real-life human decision-making is central to inform effective, human-centric public policy. Here, we report larger trends and synthesize preliminary lessons from behavioral economic and neuro-economic investigations focusing on environmental values. We review the currently available evidence at different levels of granularity, from insights into how individuals value natural resources (individual level), evidence from work on group externalities, common pool resources, and social norms (social group level) to the study of incentives, policies, and their impact (institutional level). At each level, we identify viable directions for future scientific research and actionable items for policy-makers. Coupled with new technological and methodological advances, we suggest that behavioral economic and neuroeconomic insights may inform an effective strategy to optimize environmental resources. We conclude that the time is ripe for action to enrich policies with scientifically grounded insights, making an impact in the interest of current and future generations.

    https://www.annualreviews.org/doi/full/10.1146/annurev-resource-101722-082743
  • Ulrike Kuhl, André Artelt, Barbara Hammer, "For Better or Worse: The Impact of Counterfactual Explanations’ Directionality on User Behavior in xAI"

    Counterfactual explanations (CFEs) are a popular approach in explainable artificial intelligence (xAI), highlighting changes to input data necessary for altering a model’s output. A CFE can either describe a scenario that is better than the factual state (upward CFE), or a scenario that is worse than the factual state (downward CFE). However, potential benefits and drawbacks of the directionality of CFEs for user behavior in xAI remain unclear. The current user study (N = 161) compares the impact of CFE directionality on behavior and experience of participants tasked to extract new knowledge from an automated system based on model predictions and CFEs. Results suggest that upward CFEs provide a significant performance advantage over other forms of counterfactual feedback. Moreover, the study highlights potential benefits of mixed CFEs improving user performance compared to downward CFEs or no explanations. In line with the performance results, users’ explicit knowledge of the system is statistically higher after receiving upward CFEs compared to downward comparisons. These findings imply that the alignment between explanation and task at hand, the so-called regulatory fit, may play a crucial role in determining the effectiveness of model explanations, informing future research directions in (xAI). To ensure reproducible research, the entire code, underlying models and user data of this study is openly available: https://github.com/ukuhl/DirectionalAlienZoo

    https://doi.org/10.1007/978-3-031-44070-0_14
  • André Artelt, Kleanthis Malialis, Christos G. Panayiotou, Marios Polycarpou, Barbara Hammer, "Unsupervised Unlearning of Concept Drift with Autoencoders"

    Concept drift refers to a change in the data distribution affecting the data stream of future samples. Consequently, learning models operating on the data stream might become obsolete, and need costly and difficult adjustments such as retraining or adaptation. Existing methods usually implement a local concept drift adaptation scheme, where either incremental learning of the models is used, or the models are completely retrained when a drift detection mechanism triggers an alarm. This paper proposes an alternative approach in which an unsupervised and model-agnostic concept drift adaptation method at the global level is introduced, based on autoencoders. Specifically, the proposed method aims to “unlearn” the concept drift without having to retrain or adapt any of the learning models operating on the data. An extensive experimental evaluation is conducted in two application domains. We consider a realistic water distribution network with more than 30 models in-place, from which we create 200 simulated data sets / scenarios. We further consider an image-related task to demonstrate the effectiveness of our method.

    https://doi.org/10.1109/SSCI52147.2023.10372001
  • Valerie Vaquet, Johannes Brinkrolf, Barbara Hammer, "Robust Feature Selection and Robust Training to Cope with Hyperspectral Sensor Shifts"

    Hyperspectral imaging is a suitable measurement tool across domains. However, when combined with machine learning techniques, frequently intensity and transversal shifts hinder the transfer between different sensors and settings. Established approaches focus on eliminating sensor shifts in the data or recalibrating sensors. In this contribution, we target the training procedure, propose robust training, and derive a robust feature selection strategy that can cope with multiple shift dynamics at the same time. We evaluate our approaches experimentally on artificial and real-world datasets.

    https://www.esann.org/sites/default/files/proceedings/2023/ES2023-158.pdf
  • Fabian Hinder, Valerie Vaquet, Johannes Brinkrolf, Barbara Hammer, "Model-based explanations of concept drift"

    Concept drift refers to the phenomenon that the distribution generating the observed data changes over time. If drift is present, machine learning models can become inaccurate and need adjustment. While there do exist methods to detect concept drift or to adjust models in the presence of observed drift, the question of explaining drift, i.e., describing the potentially complex and high dimensional change of distributions in a human-understandable fashion, has hardly been considered so far. This problem is of importance since it enables an inspection of the most prominent characteristics of how and where drift manifests. Hence, it allows human understanding of the change and it increases acceptance of life-long learning models. In this paper, we present a novel technology characterizing concept drift in terms of the characteristic change of spatial features based on various explanation techniques. To do so, we propose a methodology to reduce the explanation of concept drift to an explanation of models that are trained in a suitable way to extract relevant information from the drift. This way, a large variety of explanation schemes is available, and a suitable method can be selected for the problem at hand. We outline the potential of this approach and demonstrate its usefulness in several examples.

    https://doi.org/10.1016/j.neucom.2023.126640
  • Kyriakou et al., "EPyT: An EPANET-Python Toolkit for Smart Water Network Simulations"

    This paper introduces EPyT, an open-source Python package for providing a Python-based programming interface with the open-source hydraulic and quality modeling software EPANET, created by the US Environmental Protection Agency. EPyT extends the standard capabilities of the EPANET library, through the addition of new methods for research purposes. In addition to the extensive Application Programming Interface, EPyT is accompanied by a collection of water distribution benchmarks and more than 25 code examples that researchers can use as a starting point.

    https://joss.theoj.org/papers/10.21105/joss.05947#
  • Janine Strotherm, Barbara Hammer "Fairness-Enhancing Ensemble Classification in Water Distribution Networks"

    As relevant examples such as the future criminal detection software show, fairness of AI-based and social domain affecting decision support tools constitutes an important area of research. In this contribution, we investigate the applications of AI to socioeconomically relevant infrastructures such as those of water distribution networks (WDNs), where fairness issues have yet to gain a foothold. To establish the notion of fairness in this domain, we propose an appropriate definition of protected groups and group fairness in WDNs as an extension of existing definitions. We demonstrate that typical methods for the detection of leakages in WDNs are unfair in this sense. Further, we thus propose a remedy to increase the fairness which can be applied even to non-differentiable ensemble classification methods as used in this context.

    https://github.com/jstrotherm/FairnessInWDNS https://doi.org/10.1007/978-3-031-43085-5_10
  • Paul Stahlhofen, André Artelt, Luca Hermes, Barbara Hammer "Adversarial Attacks on Leakage Detectors in Water Distribution Networks"

    Many Machine Learning models are vulnerable to adversarial attacks: One can specifically design inputs that cause the model to make a mistake. Our study focuses on adversarials in the security-critical domain of leakage detection in water distribution networks (WDNs). As model input in this application consists of sensor readings, standard adversarial methods face a challenge. They have to create new inputs that still comply with the underlying physics of the network. We propose a novel approach to construct adversarial attacks against Machine Learning based leakage detectors in WDNs. In contrast to existing studies, we use a hydraulic model to simulate leaks in the water network. The adversarial attacks are then constructed based on these simulations, which makes them intrinsically physics-constrained. The adversary maximizes water loss by finding the least sensitive point, that is, the point at which the largest possible undetected leak could occur. We provide a mathematical formulation of the least sensitive point problem together with a taxonomy of adversarials in WDNs, in order to relate our work to other possible approaches in the field. The problem is then solved using three different algorithmic approaches on two benchmark WDNs. Finally, we discuss the results and reflect on potentials to enhance model robustness based on knowledge about adversarial weaknesses.

    https://doi.org/10.1007/978-3-031-43078-7_37
  • Innam Ashraf, Luca Hermes, André Artelt, Barbara Hammer "Spatial Graph Convolution Neural Networks for Water Distribution Systems"

    We investigate the task of missing value estimation in graphs as given by water distribution systems (WDS) based on sparse signals as a representative machine learning challenge in the domain of critical infrastructure. The underlying graphs have a comparably low node degree and high diameter, while information in the graph is globally relevant, hence graph neural networks face the challenge of long term dependencies. We propose a specific architecture based on message passing which displays excellent results for a number of benchmark tasks in the WDS domain. Further, we investigate a multi-hop variation, which requires considerably less resources and opens an avenue towards big WDS graphs.

    https://doi.org/10.1007/978-3-031-30047-9_3
  • Jonathan Jakob, André Artelt, Martina Hasenjäger, Barbara Hammer "Interpretable SAM-kNN Regressor for Incremental Learning on High-Dimensional Data Streams"

    In many real-world scenarios, data are provided as a potentially infinite stream of samples that are subject to changes in the underlying data distribution, a phenomenon often referred to as concept drift. A specific facet of concept drift is feature drift, where the relevance of a feature to the problem at hand changes over time. High-dimensionality of the data poses an additional challenge to learning algorithms operating in such environments. Common scenarios of this nature can for example be found in sensor-based maintenance operations of industrial machines or inside entire networks, such as power grids or water distribution systems. However, since most existing methods for incremental learning focus on classification tasks, efficient online learning for regression is still an underdeveloped area. In this work, we introduce an extension to the SAM-kNN Regressor that incorporates metric learning in order to improve the prediction quality on data streams, gain insights into the relevance of different input features and based on that, transform the input data into a lower dimension in order to improve computational complexity and suitability for high-dimensional data. We evaluate our proposed method on artificial data, to demonstrate its applicability in various scenarios. In addition to that, we apply the method to the real-world problem of water distribution network monitoring. Specifically, we demonstrate that sensor faults in the water distribution network can be detected by monitoring the feature relevances computed by our algorithm.

    https://doi.org/10.1080/08839514.2023.2198846
  • Ulrike Kuhl, André Artelt, Barbara Hammer " Let's go to the Alien Zoo: Introducing an experimental framework to study usability of counterfactual explanations for machine learning"

    Introduction
    To foster usefulness and accountability of machine learning (ML), it is essential to explain a model's decisions in addition to evaluating its performance. Accordingly, the field of explainable artificial intelligence (XAI) has resurfaced as a topic of active research, offering approaches to address the “how” and “why” of automated decision-making. Within this domain, counterfactual explanations (CFEs) have gained considerable traction as a psychologically grounded approach to generatepost-hocexplanations. To do so, CFEs highlight what changes to a model's input would have changed its prediction in a particular way. However, despite the introduction of numerous CFE approaches, their usability has yet to be thoroughly validated at the human level.

    Methods
    To advance the field of XAI, we introduce the Alien Zoo, an engaging, web-based and game-inspired experimental framework. The Alien Zoo provides the means to evaluate usability of CFEs for gaining new knowledge from an automated system, targeting novice users in a domain-general context. As a proof of concept, we demonstrate the practical efficacy and feasibility of this approach in a user study.

    Results
    Our results suggest the efficacy of the Alien Zoo framework for empirically investigating aspects of counterfactual explanations in a game-type scenario and a low-knowledge domain. The proof of concept study reveals that users benefit from receiving CFEs compared to no explanation, both in terms of objective performance in the proposed iterative learning task, and subjective usability.

    https://doi.org/10.3389/fcomp.2023.1087929
  • Kleanthis Malialis , Christos G. Panayiotou, Marios M. Polycarpou, "Nonstationary data stream classification with online active learning and siamese neural networks"

    We have witnessed in recent years an ever-growing volume of information becoming available in a streaming manner in various application areas. As a result, there is an emerging need for online learning methods that train predictive models on-the-fly. A series of open challenges, however, hinder their deployment in practice. These are, learning as data arrive in real-time one-by-one, learning from data with limited ground truth information, learning from nonstationary data, and learning from severely imbalanced data, while occupying a limited amount of memory for data storage. We propose the ActiSiamese algorithm, which addresses these challenges by combining online active learning, siamese networks, and a multi-queue memory. It develops a new density-based active learning strategy which considers similarity in the latent (rather than the input) space. We conduct an extensive study that compares the role of different active learning budgets and strategies, the performance with/without memory, the performance with/without ensembling, in both synthetic and real-world datasets, under different data nonstationarity characteristics and class imbalance levels. ActiSiamese outperforms baseline and state-of-the-art algorithms, and is effective under severe imbalance, even only when a fraction of the arriving instances’ labels is available. We publicly release our code to the community.

    https://www.sciencedirect.com/science/article/pii/S0925231222011481
  • Stelios G. Vrachimis; Demetrios G. Eliades; Riccardo Taormina; Zoran Kapelan; Avi Ostfeld; Shuming Liu; Marios Kyriakou; Pavlos Pavlou; Mengning Qiu; and Marios M. Polycarpou, "Battle of the Leakage Detection and Isolation Methods"

    A key challenge in designing algorithms for leakage detection and isolation in drinking water distribution systems is the performance evaluation and comparison between methodologies using benchmarks. For this purpose, the Battle of the Leakage Detection and Isolation Methods (BattLeDIM) competition was organized in 2020 with the aim to objectively compare the performance of methods for the detection and localization of leakage events, relying on supervisory control and data acquisition (SCADA) measurements of flow and pressure sensors installed within a virtual water distribution system. Several teams from academia and the industry submitted their solutions using various techniques including time series analysis, statistical methods, machine learning, mathematical programming, met-heuristics, and engineering judgment, and were evaluated using realistic economic criteria. This paper summarizes the results of the competition and conducts an analysis of the different leakage detection and isolation methods used by the teams. The competition results highlight the need for further development of methods for leakage detection and isolation, and also the need to develop additional open benchmark problems for this purpose.

    https://ascelibrary.org/doi/full/10.1061/%28ASCE%29WR.1943-5452.0001601
  • Ina Vertommen, Djordje Mitrović, Karel van Laarhoven, Pieter Piens and Maarten Torbeyns: "Optimization of Water Network Topology and Pipe Sizing to Aid Water Utilities in Deciding on a Design Philosophy: A Real Case Study in Belgium"

    Numerical optimization is gradually finding its way into drinking water practice. For successful introduction of optimization into the sector, it is important that researchers and utility experts work together on the problem formulation with the water utility experts. Water utilities heed the solutions provided by optimization techniques only when the underlying approach and performance criteria match their specific goals. In this contribution, we demonstrate the application of numerical optimization on a real-life problem. The Belgian utility De Watergroep is looking to not only reinforce its distribution networks but to also structurally modify the network’s topology to enhance the quality of water delivered in the future. To help the utility explore the possibilities of these far-reaching changes in the most flexible way possible, an optimization problem was formulated to optimize topology and pipe sizing simultaneously for the distribution network of a Belgian city. The objective of the problem is to minimize the volume of the looped network and thereby work towards a situation where most of the customers are fed by branched extremities of the network. This objective is constrained by pressure and fire flow requirements and thresholds on the number of customers on the branched sections. The requirements for continuity of supply under failure scenarios are guaranteed by these constraints, as verified in the final solution. The results of the optimization process show that it is possible to design a network which is 18.5% cheaper than the currently existing network. Moreover, it turns out the—previously completely meshed—topology can be restructured so that 67% of the network length is turned into branched clusters, with a meshed superstructure of 33% of the length remaining.

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  • Lydia Tsiami, Christos Makropoulos and Dragan Savic: "A review on staged design of water distribution networks"

    Water distribution networks (WDNs) evolve continuously over time. Changes in water

    demands and pipe deterioration require construction upgrades to be performed on the

    network during its entire lifecycle. However, strategically planning WDNs, especially for the

    long term, is a challenging task. This is because parameters that are essential for the

    description of WDNs in the future, such as climate, population and demand transitions, are

    characterized by deep uncertainty. To cope with future uncertainty, and avoid overdesign or

    costly unplanned and reactive interventions, research is moving away from the static design

    of WDNs. Dynamic design approaches, aim to make water networks adaptive to changing

    conditions over long planning horizons. A promising, dynamic design approach is the staged

    design of WDNs, in which the planning horizon is divided into construction phases. This

    approach allows short-term interventions to be made, while simultaneously considering the

    expected long-term network growth outcomes. The aim of this paper is to summarize the

    current state of the art in staged design of water distribution networks. To achieve that, we

    critically examined relevant publications and classified them according to their shared key

    characteristics, such as the nature of the design problem (new or existing network design,

    expansion, strengthening, and rehabilitation), problem formulation (objective functions,

    length of planning horizon), optimization method, and uncertainty considerations. In the

    process, we discuss the latest findings in the literature, highlight the major contributions of

    staged design on water distribution networks, and suggest future research directions.

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  • Dragan Savić, Barbara Hammer, Phoebe Koundouri, Marios Polycarpou: " Long term transitioning of water distribution systems"

    The percentage of the world population living in urban settlements is expected to increase to

    70% of 9.7 billion by 2050. Historically, as cities grew, the development of new water

    infrastructures followed as needed. However, these developments had less to do with real

    planning than with reacting to crisis situations and urgent needs, due to the inability of urban

    water planners to consider long-term, deeply uncertain and ambiguous factors affecting urban

    development and water demand. The “Smart Water Futures: Designing the Next Generation of

    Urban Drinking Water Systems” or “Water-Futures” project, which was funded by the

    European Research Council (ERC), aims to develop a new theoretical framework for the

    allocation and development decisions on drinking water infrastructure systems so that they

    are: (i) socially equitable, (ii) economically efficient, and (iii) environmentally resilient, as

    advocated by the UN Agenda 2030, Sustainable Development Goals. The ERC Synergy grant

    project tackles the “wicked problem” of transitioning water distribution systems in a holistic

    manner, involving civil engineering, control engineering, machine learning, decision theory

    and environmental economics expertise. Developing a theoretical foundation for designing

    smart water systems that can deliver optimally robust and resilient decisions for short/long-

    term planning is one of the biggest challenges that future cities will be facing. This paper

    presents an overview of related past research on this topic, the knowledge gaps in terms of

    investigating the problem in a holistic manner, and the key early outcomes of the project.

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  • Vaquet V., Artelt A., Brinkrolf J. and Hammer B., "Taking Care of Our Drinking Water: Dealing with Sensor Faults in Water Distribution Networks"

    Vaquet V., Artelt A., Brinkrolf J. and Hammer B., "Taking Care of Our Drinking Water: Dealing with Sensor Faults in Water Distribution Networks", ICANN 2022

    The water supply is part of the critical infrastructure as the accessibility of clean drinking water is essential to ensure the health of the people. To guarantee the availability of fresh water, efficient and reliable water distribution networks are crucial. Monitoring these systems is necessary to avoid deterioration in water quality, deal with leakages and prevent cyber-physical attacks. While the installation of a growing amount of sensors is increasing the possibilities to monitor the system, considering the control of the senors becomes another challenge as sensor faults negatively influence the reliability of systems dealing with leakages and monitoring water quality. In this work, we aim to overcome the negative implications induced by sensor faults by using a sensor fault monitoring system based on three steps. First, established residual based fault detection is applied. In a second step, we extend this method to a fault isolation technique and finally propose fault accommodation by standard imputation techniques and different types of virtual sensors.

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  • Jakob J., Artelt A., Hasenjäger M. and Hammer B., "SAM-kNN Regressor for Online Learning in Water Distribution Networks"

    Jakob J., Artelt A., Hasenjäger M. and Hammer B., "SAM-kNN Regressor for Online Learning in Water Distribution Networks", ICANN 2022

    Water distribution networks are a key component of modern infrastructure for housing and industry. They transport and distribute water via widely branched networks from sources to consumers. In order to guarantee a working network at all times, the water supply company continuously monitors the network and takes actions when necessary – e.g. reacting to leakages, sensor faults and drops in water quality. Since real world networks are too large and complex to be monitored by a human, algorithmic monitoring systems have been developed. A popular type of such systems are residual based anomaly detection systems that can detect events such as leakages and sensor faults. For a continuous high quality monitoring, it is necessary for these systems to adapt to changed demands and presence of various anomalies.

    In this work, we propose an adaption of the incremental SAM-kNN classifier for regression to build a residual based anomaly detection system for water distribution networks that is able to adapt to any kind of change.

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  • Artelt A., Vrachimis S., Eliades D., Polycarpou M. and Hammer B., "One Explanation to Rule them All -- Ensemble Consistent Explanations"

    Artelt A., Vrachimis S., Eliades D., Polycarpou M. and Hammer B., "One Explanation to Rule them All -- Ensemble Consistent Explanations", XAI workshop at IJCAI 2022

    Transparency is a major requirement of modern AI based decision making systems deployed in real world. A popular approach for achieving transparency is by means of explanations. A wide variety of different explanations have been proposed for single decision making systems. In practice it is often the case to have a set (i.e. ensemble) of decisions that are used instead of a single decision only, in particular in complex systems. Unfortunately, explanation methods for single decision making systems are not easily applicable to ensembles -- i.e. they would yield an ensemble of individual explanations which are not necessarily consistent, hence less useful and more difficult to understand than a single consistent explanation of all observed phenomena. We propose a novel concept for consistently explaining an ensemble of decisions locally with a single explanation -- we introduce a formal concept, as well as a specific implementation using counterfactual explanations.

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  • Guittard, A., Kastanidi, E., Akinsete, E., Berg, H., Carter, C., Maneas, G., Martínez-López, J., Martínez-Fernandez, J., Papadatos, D., de Vente, J., Vernier, F., Tiller, R., Karageorgis, A. P., & Koundouri, P. (2024). Using multi-actor labs as a tool to drive sustainability transitions in coastal-rural territories: Application in three European regions. GAIA – Ecological Perspectives for Science and Society, 33(1), 57–63. https://doi.org/10.14512/gaia.33.s1.9

    Evidence on the efficacy of impacts from real-world experiments in triggering transformative processes is still scarce. This study evaluates multi-actor labs to provide examples of direct impacts of real-world experiments in tackling long-standing, local, sustainability challenges.

    Multi-actor labs (MALs), a form of real-world social experiments, were implemented in three coastal-rural regions in France (Charente River Basin), Spain (Mar Menor), and Greece (South-West Messinia) to better assess and tackle coastal-rural interactions that govern local sustainability challenges, such as water use conflicts and biodiversity degradation. The MALs used participative methodologies based on systems thinking and transition management. Stakeholders were continuously engaged in a series of workshops to co-produce knowledge, reach a common understanding of the sustainability challenges and issues at stake, and co-design solutions in the form of a roadmap for sustainable transitions in coastal-rural regions. This paper evaluates MALs to provide examples of successful sustainability transition experiments based on the outputs produced, outcomes achieved, and processes used in the three coastal, rural regions.

    View here
  • Akinsete, E., Velias, A., & Koundouri, P. (2024). Integrating experimental economics and living labs in water resources management. In Economics 2024 (pp. 147–150). Edward Elgar Publishing. https://doi.org/10.4337/9781802202946.00041

    This authoritative Encyclopedia provides an innovative approach to theory, reviews, applications and examples relevant to the basic concepts of water science and water management issues in order to facilitate better interdisciplinary cooperation.

    View Here
  • Koundouri, P., Alamanos, A., Dellis, K., Landis, C., & Stratopoulou, A. (2024). Ecosystem Services into Water Resource Planning and Management. Oxford Research Encyclopedia of Environmental Science

    The broad economic notion of ecosystem services (ES) refers to the benefits that humans derive, directly or indirectly, from ecosystem functions. Provisioning ES refer to human-centered benefits that can be extracted from nature (e.g., food, drinking water, timber, wood fuel, natural gas, oils, etc.), whereas regulating ES include ecosystem processes that moderate natural phenomena (pollination, decomposition, flood control, carbon storage, climate regulation, etc.). Cultural ES entail nonmaterial benefits accruing to the cultural advancement of people, such as the role of ecosystems in national and supranational cultures, recreation, and the spur of knowledge and creativity (music, art, architecture). Finally, supporting ES refer to the main natural cycles that nature needs to function, such as photosynthesis, nutrient cycling, the creation of soils, and the water cycle. Most ES either depend on or provide freshwater services, so they are linked to water resources management (WRM). The concept of ES initially had a pedagogical purpose to raise awareness on the importance of reasonable WRM; later, however, it started being measured with economic methods, and having policy implications.

    The valuation of ES is an important methodology aimed at achieving environmental, economic and sustainability goals. The total economic value of ecosystems includes market values (priced) as well as nonmarket values (not explicit in any market) of different services for humanity’s benefit. The valuation of ES inherently reflects human preferences and perceptions regarding the contribution of ecosystems and their functions to the economy and society. The ES concept and associated policies have been criticized on the technical weaknesses of the valuation methods, interdisciplinary conflicts (e.g., ecological vs. economic perception of value), and ethical aspects on the limits of economics, nature’s commodification, and its policy implications.

    Since valuation affects the incentives and policies aimed at conserving key ES, e.g., through payment schemes, it is important to understand the way that humans decide and develop preferences under uncertainty. Behavioral economics attempts to understand human behavior and psychology and can help to identify appropriate institutions and policies under uncertainty that enhance ecosystem services that are key to WRM.

    https://doi.org/10.1093/acrefore/9780199389414.013.801
  • Phoebe Koundouri & Nikitas Pittis & Panagiotis Samartzis, 2024. “Comparative Ignorance as an Explanation of Ambiguity Aversion and Ellsberg Choices: A Survey with a New Proposal for Bayesian Training,” DEOS Working Papers 2408, Athens University of Economics and Business

    Ellsberg-type choices (Ellsberg's paradox) are evidence against the Bayesian theory of Subjective Expected Utility Maximization (SEUM). These choices reflect a particular attitude of the decision maker (DM), namely Ambiguity Aversion (AA). There are two competing interpretations of AA. The first recognizes AA as rational behavior, while the second views AA as a manifestation of a psychological fallacy. This paper focuses on the second interpretation of AA and specifically discusses the most important psychological explanation of AA that has been proposed in the literature, namely Fox and Tversky's (1995) Comparative Ignorance Hypothesis (CIH). CIH holds that AA is mainly a "comparative effect" that occurs when DM feels that he is epistemically inferior for some events of interest compared to others (for which she believes to be epistemically superior). As a result, DM exhibits an aversion towards betting on the epistemically inferior events. The purpose of the paper is twofold: First, to provide a survey of the literature on CIH. Second, to propose a novel "Bayesian Training" (BT) procedure based on "counterfactual thinking". A decision maker who finds BT attractive is likely to move out of the state of comparative ignorance, thereby ceasing to exhibit AA and joining the Bayesian camp.

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  • Alamanos, A., & Koundouri, P. (2024, November). Estimating the water requirements per sector in Europe. Paper presented at the 5th IAHR Young Professionals Congress, Online.

    This study addresses the estimation of water requirements across various sectors-domestic, agricultural, livestock, and industrial-within Europe (including the EU 27, UK, Norway, Switzerland, and the Balkans). Traditionally, water demand assessments have been limited to specific sectors or regions, making comprehensive data-driven assessments challenging. This research introduces a simple, data-efficient model developed in MS Excel and Python, allowing monthly estimates per sector. Urban water needs are calculated by multiplying population by daily per capita consumption rates. Livestock needs are similarly assessed using animal population and consumption data. Industrial water usage is derived from typical consumption rates per product types, and economic activity levels across key industries. Agricultural water demand is estimated based on crop mix, climatic, and irrigation factors. The model's results highlight significant variability in water needs across countries and sectors, validated by cross-referencing various data sources and literature. The study highlights the necessity to consider strategies for improving water demand management.

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  • Koundouri, P., Alamanos, A., & Sachs, J. D. (2024, September). A global climate hub to bridge science and society. Paper presented at the International Conference on Sustainable Development (ICSD 2024), Online.

    In recent decades, our societies increasingly face unprecedented threats (Princiotta andLoughlin 2014) . The impacts of climate change are becoming more evident, alongsidethe degradation of limited natural resources and ecosystems, unsustainable demand,production and consumption practices, biodiversity collapse, diseases, energy and foodcrises, recessions and debt crises, population crises with unequal growth anddistribution, population movements due to geopolitical and climate crises, and variousforms of inequality (Chancel 2022; Bruckner et al. 2022). Addressing theseinterconnected challenges requires urgent and coordinated efforts for globallysustainable solutions, ensuring the resilience and well- being of present and futuregenerations (Liu et al. 2015). These solutions must be based on holistic and systemicapproaches to efficiently manage the intricate interplays between environmental,economic, and social factors, while also being socially just and acceptable to ensuretheir applicability.The UN’s Sustainable Development Solutions Network (SDSN) brings together scientificand technological expertise to assess issues related to climate, energy, socio-economics, water, and biodiversity, promoting solutions for achieving the SustainableDevelopment Goals (SDGs) and the Paris Climate agreement (SDSN 2022). The SDSNviews the SDGs framework as the blueprint for addressing the aforementioned multi-crises.In this era marked by increased collaboration among scientific fields and technologicaladvances (Alamanos and Koundouri 2022), it is becoming more ‘attractive’ to transitiontoward interdisciplinary and holistic responses to complex challenges (Hernandez-Aguilera et al. 2021). Building on this interdisciplinary space and the opportunities itprovides for innovation, we established a Global Climate Hub (GCH) under the SDSN(SDSN 2023; Alamanos 2024b). This is a concerted effort to institutionalize cross-country interdisciplinary collaboration that is scientifically based and policy-oriented.

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  • Koundouri, P., Papayiannis, G. I., Petracou, E. V., & Yannacopoulos, A. N. (2024). Consensus Group Decision making under model uncertainty with a view towards environmental policy making. Environmental and Resource Economics

    In this paper we propose a consensus group decision making scheme under model uncertainty consisting of an iterative two-stage procedure based on the concept of Fréchet barycenter. Each stage consists of two steps: the agents first update their position in the opinion metric space adopting a local barycenter characterized by the agents’ immediate interactions and then a moderator makes a proposal in terms of a global barycenter, checking for consensus at each stage. In cases of large heterogeneous groups, the procedure can be complemented by an auxiliary initial homogenization stage, consisting of a clustering procedure in opinion space, leading to large homogeneous groups for which the aforementioned procedure will be applied. The scheme is illustrated in examples motivated from environmental economics.

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  • Koundouri, Phoebe, Alamanos, A., Plataniotis, A., Stavridis, C., Perifanos, K., & Devves, S. (2024). Assessing the sustainability of the European Green Deal and its interlin kages with the SDGs NATURE: Climate Action, 3(1).

    The European Green Deal (EGD) is the growth strategy for Europe, covering multiple domains, and aiming to an equitable, climate neutral European Union by 2050. The UN Agenda 2030, encompassing 17 Sustainable Development Goals (SDGs), establishes the foundation for a global sustainability transition. The integration of the SDGs into the EGD is an overlooked issue in the literature, despite Europe’s slow progress to achieve the sustainability targets. We employed a machine-learning text-mining method to evaluate the extent of SDG integration within the 74 EGD policy documents published during 2019–2023. The findings reveal a substantial alignment of EGD policies with SDGs related to clean energy (SDG7), climate action (SDG13), and sustainable consumption and production (SDG12). In contrast, there is a significant underrepresentation in areas related to social issues such as inequalities, poverty, hunger, health, education, gender equality, decent work, and peace, as indicated by lower alignment with SDGs 1, 2, 3, 4, 5, 8, 10, and 16. Temporal trends suggest a marginal increase in the attention given to environmental health (especially water and marine life) and gender equality. Furthermore, we illustrate the alignment of EGD policies with the six essential sustainability transformations proposed by the Sustainable Development Solutions Network (SDSN) in 2019 for the operationalization of the SDGs. The results indicate that besides the prevalence of “Energy Decarbonization and Sustainable Industry”, all areas have received attention, except for the “Health, Wellbeing and Demography”. The findings call for a more integrated approach to address the complete spectrum of sustainability in a balanced manner.

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  • Chatzistamoulou, N., & Koundouri, P. (2024). Is green transition in Europe fostered by energy and environmental efficiency feedback loops? the role of eco-innovation, Renewable Energy and Green Taxation.

    Chatzistamoulou, N., & Koundouri, P. (2024). Is green transition in Europe fostered by energy and environmental efficiency feedback loops? the role of eco-innovation, Renewable Energy and Green Taxation. Environmental and Resource Economics.

    Green transition is in the core of the European policy agenda to achieve the ambitious goal of climate neutrality following the launch of the European Green Deal. The cornerstone of the new growth strategy of Europe is resource efciency which focuses on shifting to a more sustainable production paradigm by conserving scarce resources and by prioritizing enhanced environmental performance. Scattered eforts to investigate the drivers of resource efciency measures have shed light on the key drivers, however, those consider resource efciency measures in isolation neglecting for feedback loops infuencing green transition. Therefore, we develop a conceptual framework to study green transition as a system of resource efciency measures afected by feedback loops, path dependence, green technologies, and green policy tools. We mobilize the analysis by devising a unique balanced panel covering the EU-28 from 2010 through 2019, including policy eforts paving the way for green transition. Econometric results based on a system of fractional probit models, indicate that resource efciency measures are intertwined via feedback loops, especially in the case of environmental efciency. Green technologies afect green transition, however, rebound efects emerge in the case of energy efciency. Past performance afects current levels pushing towards divergence. Evidence suggests that green taxation fosters energy efciency whereas hinders environmental efciency. The asymmetric operation of feedback loops and green taxation on energy and environmental efciency highlights that horizontal policies hinder rather than foster green transition. This study contributes to SDGs 7, 12, 13 and 16.

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  • Koundouri, P., Alamanos, A., Devves, S., Landis, C., & Dellis, K. (2024). Innovations for Holistic and Sustainable Transitions. Energies, 17(20), 5184.

    Energy system planning has evolved from a narrow focus on engineering and supply works towards addressing more complex, multifactorial challenges. Increasingly challenged by climate change, extreme events, economic shocks, and altered supply demand patterns, the analysis of energy systems requires holistic approaches based on data-driven models, taking into account key socio-economic factors. We draw insights from reviewing the literature, indicating the need to cover the following major gaps: the shift to transdisciplinary approaches, incorporating environmental system analysis; resilient and sustainable energy designs based on flexible portfolios of renewable mixes; the integration of socio-economic aspects, economic analyses and behavioural models to ensure energy systems are not only technically sound but socially acceptable and viable; the need for stakeholder engagement considering the human angle in energy security and behavioural shifts. Responding to these pressing challenges and emerging needs, the Global Climate Hub (GCH) initiative, operating under the UN Sustainable Development Solutions Network, offers a conceptual framework, leveraging transdisciplinary approaches. In this Concept Paper, we present for the first time the idea of the GCH as a framework that we believe has the potential to address the modern holistic needs for energy system analysis and policymaking. By setting the conceptual/theoretical ground of our suggested approach, we aim to provide guidance for innovative combinations of cutting-edge models, socio-economic narratives, and inclusive interaction with relevant stakeholders for the development and the long-term implementation of sustainable pathways.

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  • Zanutto, D., Michalopoulos, C., Chatzistefanou, G. -A., Vamvakeridou-Lyroudia, L., Tsiami, L., Glynis, K., Samartzis, P., Hermes, L., Hinder, F., Vaquet, J., Vaquet, V., Eliades, D., Polycarpou, M., Koundouri, P., Hammer, B., & Savić, D. (2024). A Water Futures Approach on Water Demand Forecasting with Online Ensemble Learning. Engineering Proceedings, 69(1), 60

    This study presents a collaborative framework developed by the Water Futures team of researchers for the “Battle of the Water Demand Forecasting” challenge at the 3rd International WDSA-CCWI Joint Conference. The framework integrates an ensemble of machine learning forecasting models into a deterministic outcome consistent with the competition formulation. The water demand trajectory over a week exhibits complex overlapping patterns and non-linear dependencies to multiple features and time-dependent events that a single model cannot accurately predict. As such, the reconciled forecast from an ensemble of models exceeds the performance of the individual ones and exhibits higher stability across the weeks of the year and district metered areas considered.

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  • Alamanos, A., Papaioannou, G., Varlas, G., Markogianni, V., Plataniotis, A., Papadopoulos, A., Dimitriou, E., & Koundouri, P. (2024). Designing Post-Fire Flood Protection Techniques for a Real Event in Central Greece. Prevention and Treatment of Natural Disasters, 3(2).

    Wildfires pose a growing global danger for ecosystems and human activities. The degraded ecosystem functions of burnt sites, include, among others, shifts in hydrological processes, land cover, vegetation, and soil erosion, that make them more vulnerable to flood and extreme sediment transport risks. Several post-fire erosion and flood protection treatments (PFPs) have been developed to avoid and mitigate such consequences and risks. The Mediterranean region faces severe climate change challenges that are projected to escalate the wildfire and post-fire flood risks. However, there is limited research on the dynamics of post-fire flood risks and their mitigation through the design of the appropriate PFPs. This paper aims to cover this gap by simulating a real post-fire flash-flood event in Central Greece, and design the PFPs for this case study, considering their suitability and costs. An integrated framework was used to represent the flood under the baseline scenario: the storm conditions that caused the flood were simulated using the atmospheric model WRF-ARW; the burn extent, severity, and the flood extent were retrieved through remote sensing analyses; and a HEC-RAS hydraulic-hydrodynamic model was developed to simulate the flood event, applying the rain-on-grid technique. Several PFPs were assessed, and certain channel- and barrier-based PFPs were selected as the most suitable for the study area. The recommended PFPs were spatially represented within a geographic information system (GIS). Moreover, we present a detailed analysis of their expected costs. This study provides an interdisciplinary and transferable framework for understanding and enhancing the flood resilience of burnt sites.

    https://ojs.ukscip.com/index.php/ptnd/article/view/303
  • Alamanos, A.; Koundouri, P.; Papadaki, L.; Pliakou, T.; Toli, E. Water for Tomorrow: A Living Lab on the Creation of the Science-Policy-Stakeholder Interface.

    Alamanos, A.; Koundouri, P.; Papadaki, L.; Pliakou, T.; Toli, E. Water for Tomorrow: A Living Lab on the Creation of the Science-Policy-Stakeholder Interface. Water 2022, 14, 2879.

    The proactive sustainable management of scarce water across vulnerable agricultural areas of South Europe is a timely issue of major importance, especially under the recent challenges affecting complex water systems. The Basin District of Thessaly, Greece’s driest rural region, has a long history of multiple issues of an environmental, planning, economic or administrative nature, as well as a history of conflict. For the first time, the region’s key-stakeholders, including scientists and policymakers, participated in tactical meetings during the 19-month project “Water For Tomorrow”. The goal was to establish a common and holistic understanding of the problems, assess the lessons learned from the failures of the past and co-develop a list of policy recommendations, placing them in the broader context of sustainability. These refer to enhanced and transparent information, data, accountability, cooperation/communication among authorities and stakeholders, capacity building, new technologies and modernization of current practices, reasonable demand and supply management, flexible renewable energy portfolios and circular approaches, among others. This work has significant implications for the integrated water resources management of similar south-European cases, including the Third-Cycle of the River Basin Management Plans and the International Sustainability Agendas.

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  • Pittis N., Koundouri P., Samartzis P., Englezos N. and Papandreou A., "Ambiguity aversion, modern Bayesianism and small worlds"

    Pittis N., Koundouri P., Samartzis P., Englezos N. and Papandreou A., "Ambiguity aversion, modern Bayesianism and small worlds" [version 1; peer review: 2 approved], Open Research Europe 2021, 1:13

    The central question of this paper is whether a rational agent under uncertainty can exhibit ambiguity aversion (AA). The answer to this question depends on the way the agent forms her probabilistic beliefs: classical Bayesianism (CB) vs modern Bayesianism (MB). We revisit Schmeidler's coin-based example and show that a rational MB agent operating in the context of a "small world", cannot exhibit AA. Hence we argue that the motivation of AA based on Schmeidler's coin-based and Ellsberg's classic urn-based examples, is poor, since they correspond to cases of "small worlds". We also argue that MB, not only avoids AA, but also proves to be normatively superior to CB because an MB agent (i) avoids logical inconsistencies akin to the relation between her subjective probability and objective chance, (ii) resolves the problem of "old evidence" and (iii) allows psychological detachment from actual evidence, hence avoiding the problem of "cognitive dissonance". As far as AA is concerned, we claim that it may be thought of as a (potential) property of large worlds, because in such worlds MB is likely to be infeasible.

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  • Stelios Vrachimis, Srimanta Santra, Agathoklis Agathokleous, Pavlos Pavlou, Marios Kyriakou, Michalis Psaras, Demetrios G. Eliades, Marios M. Polycarpou, "WaterSafe: A Water Network Benchmark for Fault Diagnosis Research"

    Currently, in the water distribution systems literature, fault detection methods are typically evaluated on benchmark water networks that do not include real-time experimental data, or on private commercial datasets, which prohibit the reproducibility of the results. Moreover, realistic modeling of faults on hydraulic system components, sensors and actuators is often unavailable. In this work, we provide a framework for the application of fault-diagnosis methodologies on WaterSafe, a water network benchmark for fault diagnosis. The WaterSafe benchmark is a small scale replica of a water transport network constructed using industrial components and devices, while the communications are implemented in a way that resemble a water utility's Supervisory Control and Data Acquisition system. A general problem formulation for fault-diagnosis on water systems is provided, in accordance to the mathematical model of the benchmark. Moreover, we provide a calibrated simulation model including system, sensor and actuator faults, based on observations from the real system. Finally, we provide open access to the datasets generated from the experiments containing the aforementioned faults.

    https://www.sciencedirect.com/science/article/pii/S2405896322005870
  • Koundouri, P., Papayiannis, G. I., Petracou, E. V., & Yannacopoulos, A. N. (2024). Consensus Group Decision making under model uncertainty with a view towards environmental policy making.

    Koundouri, P., Papayiannis, G. I., Petracou, E. V., & Yannacopoulos, A. N. (2024). Consensus Group Decision making under model uncertainty with a view towards environmental policy making. Environmental and Resource Economics.

    In this paper we propose a consensus group decision making scheme under model uncertainty consisting of an iterative two-stage procedure based on the concept of Fréchet barycenter. Each stage consists of two steps: the agents first update their position in the opinion metric space adopting a local barycenter characterized by the agents’ immediate interactions and then a moderator makes a proposal in terms of a global barycenter, checking for consensus at each stage. In cases of large heterogeneous groups, the procedure can be complemented by an auxiliary initial homogenization stage, consisting of a clustering procedure in opinion space, leading to large homogeneous groups for which the aforementioned procedure will be applied. The scheme is illustrated in examples motivated from environmental economics.

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  • Koundouri, P., Alamanos, A., Plataniotis, A., Stavridis, C., Perifanos, K., & Devves, S. (2024). Assessing the sustainability of the European Green Deal and its Interlin Kages with the sdgs.

    Koundouri, P., Alamanos, A., Plataniotis, A., Stavridis, C., Perifanos, K., & Devves, S. (2024). Assessing the sustainability of the European Green Deal and its Interlin Kages with the sdgs. NATURE Climate Action, 3(1).

    The European Green Deal (EGD) is the growth strategy for Europe, covering multiple domains, and aiming to an equitable, climate neutral European Union by 2050. The UN Agenda 2030, encompassing 17 Sustainable Development Goals (SDGs), establishes the foundation for a global sustainability transition. The integration of the SDGs into the EGD is an overlooked issue in the literature, despite Europe’s slow progress to achieve the sustainability targets. We employed a machine-learning text-mining method to evaluate the extent of SDG integration within the 74 EGD policy documents published during 2019–2023. The findings reveal a substantial alignment of EGD policies with SDGs related to clean energy (SDG7), climate action (SDG13), and sustainable consumption and production (SDG12). In contrast, there is a significant underrepresentation in areas related to social issues such as inequalities, poverty, hunger, health, education, gender equality, decent work, and peace, as indicated by lower alignment with SDGs 1, 2, 3, 4, 5, 8, 10, and 16. Temporal trends suggest a marginal increase in the attention given to environmental health (especially water and marine life) and gender equality. Furthermore, we illustrate the alignment of EGD policies with the six essential sustainability transformations proposed by the Sustainable Development Solutions Network (SDSN) in 2019 for the operationalization of the SDGs. The results indicate that besides the prevalence of “Energy Decarbonization and Sustainable Industry”, all areas have received attention, except for the “Health, Wellbeing and Demography”. The findings call for a more integrated approach to address the complete spectrum of sustainability in a balanced manner.

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  • Koundouri, P., Halkos, G., Landis, C. F. M., et al. (2023). Ecosystem services valuation for supporting sustainable life below water.

    Koundouri, P., Halkos, G., Landis, C. F. M., et al. (2023). Ecosystem services valuation for supporting sustainable life below water. NATURE: Sustain Earth Reviews, 6, 19.

    The significance of the SDGs lies in their holistic, global and interdisciplinary nature. But this nature at the same time poses significant challenges, as it is difficult to bridge the breadth of different aspects included in the SDGs, such as the environmental and the socio-economic, both in theory, practical application and policymaking. SDG14 on “life below water” is quite a holistic concept as it refers to a natural/environmental system (seas), supporting several marine economic activities and ecosystem values, and associated with strong social and cultural characteristics of the local populations, affecting the ways they manage marine areas. The main challenges for the achievement of a sustainable life below water are analyzed, and ways forward are discussed. Holistic and well-coordinated approaches considering the complex nature of SDG14 are necessary. Moreover, we argue on the role of economic instruments that can bridge environmental and socio-economic aspects, towards more sustainable life below water. In particular, the potential of environmental valuation as a means to better inform SDG policies, is discussed, using the example of SDG14. The currently established frameworks for Country’s Sustainability Reporting, lack metrics focusing on the economic impact of the environment and the ecosystem services’ degradation or restoration rates, including ocean and marine ecosystems. Acknowledging and quantifying the costs and benefits of ocean and marine ecosystems can lead to more effective interventions (such as ocean pollution prevention, climate change mitigation, fishing exploitation, biodiversity and coral reef preservation) and a better understanding of human-environmental dynamics. This, in turn, strengthens coordinated management and cooperation.

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  • Koundouri, P., et al. (2023) Modelling Net Zero Pathways, SDSN Global Climate Hub.

    During its first year, the Global Climate Hub has initiated a holistic approach to climate, economic, and energy modelling to deliver a first set of results. The process described in this report consist of a thorough review and assessment of potent Integrated Assessment Models (IAMs) and the delineation of a first set of sustainable pathways on the EU energy sector, the deployment, and effects of renewable energy transition in Southeast Asia and the development of sustainable pathways for land-use and food systems in Greece.
    In addition, the researchers of the GCH are examining interlinkages and complementarities across diverse IAMs which will yield horizontal and vertical synergies and elaborate on the potential pathways to net zero for 2050.
    The aim of this report is to present the work of the Global Climate Hub on net zero pathways, mirroring the work undertaken in some of its distinct units. Having established the benchmark in the current state of environmental indicators and environmental policies (operating and designed), the GCH is currently collating and evaluating scientific methods embedded in modelling systems in order to integrate strands of research into coherent environmental, energy and socioeconomic pathways.
    Section 2 briefly summarizes the review of Integrated Assessment Models (IAMs) which form the multi-dimension scientific arsenal in the pathways’ development, while section 3 outlines a first set of results stemming from energy and land-use models. More specifically, section 3.1 addresses the issue of decarbonization of the EU energy system as envisioned in the Fit-for-55 and RePowerEU initiatives through the projections of the BALMOREL model. Section 3.2 describes the pivotal role of renewable energy for bolstering ecosystem services in Southeast Asia and section 3.3 summarizes the key tenets of sustainable and-use and food system pathways for Greece using the FABLE Calculator. Finally, section 4 describes the potential for system integration under the auspices of the GCH and highlights the areas for future work in promoting net zero pathways

    Available here
  • Koundouri, P. (2023). Urgent call for comprehensive governmental climate action against wildfires in Greece.

    Koundouri, P. (2023). Urgent call for comprehensive governmental climate action against wildfires in Greece. NATURE: Climate Action, 2(1).

    In recent decades, Greece has experienced devastating wildfires, particularly during the summer months. These wildfires have intensified in frequency and severity, largely attributed by experts to the impacts of climate change. Extended periods of drought, soil aridity, persistent heatwaves, and intensified winds have transformed forests into highly vulnerable areas susceptible to even the minor spark. In many cases, the fires have been uncontrollable and can be described as “megafires.” These megafires, are enormous in scale and intensity, and pose an increasingly severe threat to Greece’s landscape, necessitating a comprehensive response to protect both the environment and citizen’s safety and well-being.

    This commentary highlights the need for comprehensive governmental climate action in response to Greece’s wildfires. It discusses the destruction of biodiversity and presents a holistic approach to fire management. Collaboration and the SDGs are emphasized as key elements in addressing climate change’s consequences.

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The Project

About the Project Concept

Research

Objectives

Team

People University of Cyprus (UCY) Bielefeld University Athens Univ. of Economics and Business (AUEB) KWR Water Research Institute (KWR) University of Exeter

This project has received funding from the European Research Council (ERC) under the ERC Synergy Grant Water-Futures (Grant agreement No. 951424).

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