Nikolaos K. Mellios

University of Thessaly | UTH · Division of Structural Engineering

EJWP NEXUSNet Report

This paper presents an architecture and a platform for processing of water management data in real time. Stakeholders in the domain are faced with the challenge of handling large amounts of incoming sensor data from heterogeneous sources after the digitalization efforts within the sector. Our water management analytical platform (WMAP) is built upo...

Cyanobacteria blooms in lakes and reservoirs currently threaten water security and affect the ecosystem services provided by these freshwater ecosystems, such as drinking water and recreational use. Climate change is expected to further exacerbate the situation in the future because of higher temperatures, extended droughts and nutrient enrichment,...

Cyanobacteria blooms in lakes and reservoirs currently threaten water security and affect the ecosystem services provided by these freshwater ecosystems, such as drinking water and recreational use. Climate change is expected to further exacerbate the situation in the future because of higher temperatures, extended droughts and nutrient enrichment,...

Cyanobacterial blooms are considered a major threat to global water security with documented impacts on lake ecosystems and public health. Given that cyanobacteria possess highly adaptive traits that favor them to prevail under different and often complicated stressor regimes, predicting their abundance is challenging. A dataset from 822 Northern E...

The paper presents a thorough evaluation of the performance of different statistical modeling techniques in ground- and surface-level prediction scenarios as well as some aspects of the application of data-driven modeling in practice (feature generation, feature selection, heterogeneous data fusion, hyperparameter tuning, and model evaluation). Twe...

Achieving the UN Sustainable Development Goals depends on using resources efficiently, avoiding fragmentation in decision-making, recognising the trade-offs and synergies across sectors and adopting an integrated Nexus thinking among policymakers. Nexus Informatics develops the science of recognising and quantifying nexus interlinkages. Nexus-coher...

Climate change represents a critical research issue due to a series of impacts that both the physical and man-made environment experience during the last years. Extremes weather events, changes in biodiversity, desertification of the most vulnerable regions and relevant socioeconomic effects are among the main consequences of such a phenomenon. Gre...

Urban water management is a key challenge nowadays and advances in information and communication technology systems show a great potential to build efficient, intelligent solutions supporting smart water management scenarios. This paper presents novel techniques for data collection, analysis and visualization developed within the Water4Cities proje...

In the ever-changing world, especially due to the climate change, another family of data-driven machine learning algorithms is needed to catch the changing dynamics. Traditional machine learning algorithms are not adjusted to the adaptation to new circumstances. They assume the distribution of the input and target values will remain constant throug...

The concept of the Water–Energy–Food nexus (WEF), as documented by the United Nations Food and Agriculture Organization (FAO), suggests that the three resources are thoroughly interrelated, shaping a complicated web of interlinkages. Perceiving the three commodities as an interdependent variable system, rather than isolated subsystems is a step tow...

The deployment of real-world water monitoring and analytics tools is still far behind the growing needs of cities, which are facing constant urbanisation and overgrowth of the population. This paper presents a full-stack data-mining infrastructure for smart water management for cities being developed within Water4Cities project. The stack is tested...

The United Nations Food and Agriculture Organization (FAO) has established the Water-Energy-Food Nexus, implying that the three commodities are inextricably linked forming a complex system of interrelations. Perceiving water, energy and food as a system variable with dependencies rather than a singularity suggests an approach of a more holistic vie...

An analysis of virtual crop water export through international trade is conducted for Greece, downscaled to the River Basin District (RBD) level, in order to identify critical "hotspots" of localized water shortage in the country. A computable general equilibrium model (MAGNET) was used to obtain the export shares of crops and associated irrigation...

To enable effective decision-making at the entire city level, both surface water and groundwater should be viewed as part of the extended urban water ecosystem with its spatiotemporal availability, quantity, quality and competing uses being taken into account. The Water4Cities project aims to build an ICT solution for the monitoring, visualization...

In this article, we focus on shallow sub-tropical lakes and study the factors that determine their trophic state and food web structure. We use the model PCLake to simulate lake nutrient dynamics and investigate key factors causing eutrophication, such as in-lake nutrient cycling, long residence time and low depths. Modeling results are validated i...

The re-flooded lakes with unique natural and cultural values that are under threat from anthropogenic pressure, consist a very important section of fresh water resources management in the Mediterranean. Lake Karla, positioned in the eastern part of Thessaly (Greece), is an example of a lake ecosystem, which was dried in the 60s to provide additiona...

Water demand forecast has emerged as an imperative component of intelligent Internet and Communication Technologies based methodologies of water management. The need of increased time resolution of forecast in order to implement such methodologies is driving stakeholders to long for new more specialized forecast approaches that will take into accou...

Cyanobacterial blooms are becoming a major water quality problem in Mediterranean lakes. The threat from the occurrence and persistence of cyanobacteria is considered high, and there is a risk that this might be increased by climate change. Approximately, 75% of water samples containing cyanobacteria also contain toxic cyanobacterial metabolites, k...

Το άρθρο εστιάζει στην ανάγκη της ενσωμάτωσης της διαχείρισης του αστικού νερού στον πολεοδομικό σχεδιασμό, στο πλαίσιο της βιωσιμότητας των πόλεων του μέλλοντος. Αρχικά παρουσιάζονται οι προκλήσεις που πρέπει να αντιμετωπιστούν στην κατεύθυνση αυτής της ολιστικής θεώρησης. Στη συνέχεια γίνεται εκτενής αναφορά στις αρχές που θα πρέπει να διέπουν το...

Pressure control management of a water distribution network is considered as an effective approach for the reduction of leakage in the network and for optimized savings in pumping energy. A successful pressure management scheme usually requires single-or multi-feed regulation through Pressure Reduction Valves, the network division in District Meter...

In the present article, we simulate Lake Karla, an important natural ecosystem under restoration in Greece, operating also as a reservoir. The lake trophic state is characterized as hypertrophic with the expected negative effects on biodiversity. The simulation of Lake Karla is a significant tool in terms of understanding, predicting and managing t...

Considering the increasing demand for the optimization of water distribution networks in terms of leakage reduction and pressure management, as well as the need to reduce urban water consumption, a lot of effort has been invested in the past decade in order to define accurate, long-term and short-term water demand forecasting methods. Linear regres...

We present an analysis of historical water demand data from the utility of Skiathos, Greece and demonstrate suitable demand forecasting methodologies. We apply linear and nonlinear forecasting methods to a three-year time series water demand. The best fit for quarterly averaged data was observed for the Winters' additive method; for monthly-average...