Dionysios Nikolopoulos

Dionysios Nikolopoulos
National Technical University of Athens | NTUA · Department of Water Resources and Environmental Engineering

MSc

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26
Publications
5,163
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151
Citations

Publications

Publications (26)
Article
Full-text available
Optimizing the design and operation of an Urban Water System (UWS) faces significant challenges over its lifespan to account for the uncertainties of important stressors that arise from population growth rates, climate change factors, or shifting demand patterns. The analysis of a UWS’s performance across interdependent subsystems benefits from a m...
Article
The interplay between cyber and physical elements of water systems and the corresponding security challenges are fast becoming a key topic for the water sector. Of special concern is the absence of simulation tools for deliberate contamination attacks on water distribution networks (WDNs), in conjunction with cyber attacks on the contamination warn...
Conference Paper
Full-text available
Our modern urban environment relies on critical infrastructures that serve vital societal functions, such as water supply and sanitation, which are exposed to various threats of both physical and cyber nature. Despite the progress in protection and increased vigilance, long-established practices within the water utilities may rely on precarious met...
Article
Full-text available
Water distribution networks (WDNs) are critical infrastructure for the welfare of society. Due to their spatial extent and difficulties in deployment of security measures, they are vulnerable to threat scenarios that include the rising concern of cyber-physical attacks. To protect WDNs against different kinds of water contamination, it is customary...
Article
This work proposes a modeling framework to quantify the effects of deliberate organic contamination events on water distribution systems. A bacterial regrowth model and a first parallel chlorine decay model were combined to describe the biochemical water species kinetics during a deliberate contaminant injection consisting of organic (TOC) and bact...
Chapter
Full-text available
Critical infrastructures of the water sector are currently undergoing a digital transformation of their assets, operations and services. The tight integration of new ICT technologies for monitoring and control with the physical processes of the water sector creates a complex cyber-physical system. Efficiency and automation advantages notwithstandin...
Article
Full-text available
This paper presents a failure quantification methodology to assess the impact of cyber-physical attacks (CPAs) on critical water infrastructures, such as water distribution networks, by mapping simulation-derived data onto metrics. The approach sets out a three-step profiling architecture to interpret the consequences of failures resulting from CPA...
Article
Full-text available
The concept of Circular Economy, although not entirely new, has in recent years gained traction due to growing concern with regards to the Earth’s natural reserves. In this context, Sewer Mining, a wastewater management method based on extracting wastewater from local sewers for reuse applications, presents an interesting option that lies in the in...
Article
Full-text available
The water sector is facing emerging challenges, as cyber-physical threats target Supervisory Control and Data Acquisition (SCADA) systems of water utilities. A cyber-physical stress-testing platform is presented in this work, named RISKNOUGHT, which is able to model water distribution networks as cyber-physical systems, simulating the information f...
Conference Paper
Full-text available
Over the last 30 years, numerous water resources planning and management studies in Greece have been conducted by using state-of-the-art methodologies and associated computational tools that have been developed by the Itia research team at the National Technical University of Athens. The spearhead of Itia’s research toolkit has been the Hydronomeas...
Conference Paper
Full-text available
Emergent threats in the water sector have the form of cyber-physical attacks that target SCADA systems of water utilities. Examples of attacks include chemical/biological contamination, disruption of communications between network elements and manipulating sensor data. RISKNOUGHT is an innovative cyber-physical stress testing platform, capable of m...
Conference Paper
Full-text available
We present a distributed hydrological model with minimal calibration requirements, which represents the rainfall-runoff transformation and the flow routing processes. The generation of surface runoff is based on a modified NRCS-CN scheme. Key novelty is the use of representative CN values, which are initially assigned to model cells on the basis of...
Article
Full-text available
Centralized urban water management currently faces multiple challenges, both at the supply side and the demand side. These challenges underpin the need to progress to the decentralization of urban water, where multiple distributed technologies (water-aware appliances, rainwater harvesting, greywater recycling, sustainable urban drainage) are applie...
Poster
Full-text available
For more than two decades, the use of artificial neural networks (ANNs) in hydrology has become an effective and efficient alternative against traditional modeling approaches, i.e. physically-based or conceptual. These can take ad-vantage of any type of available information to predict the hydrological response of complex systems, with missing data...
Article
Full-text available
The water sector is, currently and for the foreseeable future, challenged by rising levels of uncertainty in demand and availability of water, in a context of aging infrastructure and limited investment. In order to support strategic planning, water companies need a way to assess how their system behaves when faced with a range of changing conditio...
Article
Full-text available
The objective of this article is to provide a simple and effective tool for low flow forecasting up to six months ahead, with minimal data requirements, i.e. flow observations retrieved at the end of wet period (first half of April, for the Mediterranean region). The core of the methodological framework is the exponential decay function, while the...
Conference Paper
The alarming rate of urbanization poses immediate problems to water resources management, mainly, but not limited to water supply, flood risk management, wastewater treatment and water quality control. Ideally, strategic planning of water systems should be fully aware of the prospects of future urban growth in order to maintain high reliability of...
Article
Full-text available
Infrastructure planning for Urban Water Systems (UWSs) is challenged by, inter alia, increasing uncertainty in both demand and availability of water and aging infrastructure, and this is already impacting the climate-proofing of cities. In this context, the idea of resilience has been gradually embraced by the water sector, but the term itself is n...
Conference Paper
Full-text available
Περιγράφεται μια ολιστική προσέγγιση για τη διαχείριση σύνθετων συστημάτων ταμιευτήρων, οι οποίοι εξυπηρετούν πολλαπλούς και, συχνά, αντικρουόμενους στόχους, όπως είναι η παραγωγή ενέργειας και η κάλυψη αρδευτικών/ υδρευτικών ή άλλων αναγκών. Η εν λόγω διαδικασία είναι κατά κανόνα πολύπλοκη λόγω του στοχαστικού χαρακτήρα των υδρομετεωρολογικών διερ...
Article
Low flows commonly occur in rivers during dry seasons within each year. They often concur with increased water demand which creates numerous water resources management problems. This paper seeks for simple yet efficient tools for low-flow forecasting, which are easy to implement, based on the adoption of an exponential decay model for the flow rece...
Conference Paper
Full-text available
Coastal communities are increasingly at risk from coastal hazards such as floods. Extreme hydro-meteorological events related to sea level rise, storm surges, heavy precipitation, shoreline erosion are driven by climate variability and increase the exposure of people, livelihoods, environmental services, resources and infrastructure to hazard. Floo...
Poster
Full-text available
Within the ongoing research project “Combined Renewable Systems for Sustainable Energy Development” (CRESSENDO), we have developed a novel stochastic simulation framework for optimal planning and management of large-scale hybrid renewable energy systems, in which hydropower plays the dominant role. The methodology and associated computer tools are...
Conference Paper
Full-text available
Record-breaking occurrences in hydrometeorological processes are often used particularly in communicating information to the public and their analysis offers the possibility of better comprehending extreme events. However, the typical comprehension depends on prototypes characterized by pure randomness. In fact the occurrence of record breaking dep...

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