Demetris Lekkas

Demetris Lekkas
University of the Aegean · Department of Environment

PhD in Hydrology

About

45
Publications
11,355
Reads
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720
Citations
Introduction
Dr Demetris Francis Lekkas is Associate Professor in the Department of Environment (University of the Aegean, Greece). He is the Director of the Waste Management Laboratory and leader of the Analysis and Simulation of Environmental Systems research group.
Additional affiliations
September 2016 - present
University of the Aegean
Position
  • Professor (Associate)
January 2004 - December 2011
University of the Aegean
Description
  • http://www.actuar.aegean.gr/eng/ases/ases.html
March 2002 - April 2004
Imperial College London
Position
  • Research Associate
Education
September 1998 - March 2002
Imperial College London
Field of study
  • PhD in Hydrology

Publications

Publications (45)
Article
Full-text available
The standardized precipitation index (SPI) is used for characterizing and predicting meteorological droughts on a range of time scales. However, in forecasting applications, when SPI is computed on the entire available dataset, prior to model-validation, significant biases are introduced, especially under changing climatic conditions. In this paper...
Article
The treatment and disposal of organic household and industrial waste is a global issue. Several environmental, social, and economic problems are associated with current waste management practices. Composting biowaste is a financially affordable and easy-to-use method, while compost, the final product, can improve various soil properties. In this st...
Article
Full-text available
Purpose: The acquisition of reliable data on Municipal Solid Waste (MSW) composition is very important for the development of environmentally sound, sustainable and economically viable integrated waste management systems. However, no standardized universally accepted waste characterization protocol has been developed, as there are various methodolo...
Conference Paper
Full-text available
There is not a universal method for assessing the quality of composts. This can be mainly attributed to the fact that composts are assessed by means of multiple measured parameters. For the case of composts, several parameters are optimal not necessarily if maximized or minimized but ideally when they are within a specific range of values. The comm...
Conference Paper
Full-text available
The North Aegean Islands of Chios and Lesvos set recycling goals for organic residues from Municipal Solid Wastes (MSW). Both islands, in line with the National and Regional Plans for Municipal Waste Management, are discussing the approach of mechanical-biological stabilization MSW in combination with separated collection of biowastes and municipal...
Article
Full-text available
Generalized linear models (GLMs) are popular tools for simulating daily rainfall series. However, the application of GLMs in drought-prone areas is challenging, as there is inconsistency in rainfall data during long and irregular periods. The majority of studies include regions where rainfall is well distributed during the year indicating the capab...
Article
An investigation into the occurrence of priority substances regulated by 2000/60/EC Water Framework Directive and 2008/105/EC Directive was conducted for a period of one year in the surface water sources supplying the water treatment plants (WTPs) of Athens and in the raw water of WTPs. Samples from four reservoirs and four water treatment plants o...
Article
Full-text available
Hotel sector causes significant environmental stress in both natural and built up areas due to their consumption of water and energy. In addition, the production of large volumes of liquid and solid waste results in a significant environmental footprint. The use of water and energy by hotels is strongly linked (e.g. energy is consumed for hot water...
Article
Full-text available
Prediction of runoff response in ungauged catchments has been one of the key issues in water science. Despite the considerable effort, the hydrologic community has devoted over the past decade, there is still need to develop robust frameworks capable of representing the dynamic behaviours of catchment processes (e.g. streamflow). Runoff prediction...
Article
The hydrologic community has recently focused substantial attention on ungauged or poorly gauged catchments, since hydrological prediction under these conditions is highly uncertain, but represents the majority of practical applications. Catchments in Greece are usually ungauged, due to resource constrains, whilst in gauged areas the period of reco...
Article
Full-text available
Drought is a natural hazard that can affect regions for months or years resulting to both environmental and socio-economic impacts. Different drought definitions (meteorological, agricultural, hydrological and socioeconomic) can be found in literature that can be linked to spatial and temporal characteristics of an event as well as to the correspon...
Article
Full-text available
Current practices for the efficient use and management of water resources are based on the conjunctive application of water supply and demand measures. Even though options for the augmentation of water supply are widely analysed and assessed, water demand management remains an open field for study, as it is highly dependent on the socio-economic fe...
Article
Full-text available
An econometric model has been developed that represents the cost structure of water supply and waste water treatment in an urban area. This paper proposes a method to capture the fi nancial characteristics of the underlying organisation and addresses the steps and the conceptualisation in order to create a cost structure for municipal water utiliti...
Article
Full-text available
The relationship between catchment size and streamflow magnitude is a well known hydrological theory and is usually used for prediction at ungauged basins (PUB). However, the nonlinear behavior of this relationship generates a number of problems when used for flood peak prediction for design purposes due to increased uncertainty. In this study, art...
Article
Full-text available
The traditional approach to urban water management is primarily based on a supply-oriented approach, where water follows a one-way path from supply to a single use, to treatment and then discharged to the environment. The wide acknowledgement of the need to shift towards more sustainable practices has led to the recognition that demand is multi-fac...
Article
Forecasting river flow is important to water resources management and planning. Four artificial neural network (ANN) models were developed and compared in order to forecast river flow in the River Trent, UK. The first two are feed-forward networks and were trained with back-propagation and cascade-correlation algorithms; the third is an adaptive li...
Article
The aim of this paper is to elaborate strategies, methodologies and techniques for integrated water resource management within the philosophy of the EC Water Framework Directive (2000/60/EC) for the trans-boundary river basin of Evros which is shared by two EU (Greece, Bulgaria) and an EU-candidate country (Turkey). With the recent comer EU Member...
Article
Full-text available
EXTENDED ABSTRACT The traditional approach to urban water management is primarily based on a supply-oriented approach, where water follows a one-way path from supply to a single use, to treatment and then discharged to the environment. The wide acknowledgement of the need to shift towards more sustainable practices has led to the recognition that d...
Article
Polycyclic aromatic hydrocarbons (PAHs) as well as nonylphenol (NP) and octylphenol (OP) are substances of major environmental concern because of their adverse health effects on organisms, including endocrine disrupting activity. Seven PAHs, NP and OP have been included in the priority list of substances regulated by 2000/60/EC Water Framework Dire...
Article
In this paper, a variable advective time delay (ATD) is introduced to Transfer Function (TF) models. This element enables the TF model to follow the diversity in response of a catchment system much better than using a constant advective time delay value as heretofore. An investigation of different approaches to define the variation of the ATD of th...
Article
Some recent developments in the stochastic modelling of single site and spatial rainfall are summarised. Alternative single site models based on Poisson cluster processes are introduced, fitting methods are discussed, and performance is compared for representative UK hourly data. The representation of sub-hourly rainfall is discussed, and results f...
Article
Full-text available
From the abstraction point and the entrance of water in a Water System (WS) till its discharge back to the environment, water passes through a number of treatments and uses that directly affect its quality. The water quality changes several times while the water returning to the environment at a discharge point into the sea, a lake or a river has p...
Article
The pollution of the surface waters of Greece from the priority compounds of 76/464/EEC Directive was evaluated. The occurrence of 92 toxic compounds, 64 of which belong to priority compounds of List II, candidates for List I, of 76/464/EEC Directive, was studied in surface waters and wastewater through the developed network of 62 sampling stations...
Article
Full-text available
In hydrology, as in a number of diverse fields, there has been an increasing use of Artificial Neural Networks (ANN) as black-box simplified models. This is mainly justified by their ability to model complex non-linear patterns; in addition they can self-adjust and produce a consistent response when ‘trained’ using observed outputs. This paper util...
Article
Full-text available
The priority substances of List I, 76/464/EEC Directive, some of which belong to the new Water Framework Directive 2000/60/EC, have been monitored in the surface waters of Greece through the developed network of 53 sampling stations. The analytical methods used for the determination of these substances included Purge and Trap-Gas chromatography-Mas...
Article
Stochastic generation of rainfall and evaporation is required to support continuous simulation rainfall-runoff modelling for flood design. A hierarchy of methods for rainfall generation is discussed in the context of performance criteria relevant to rainfall-runoff modelling. a) For single site rainfall, Poisson-based models have been widely invest...
Article
A survey undertaken in Northern Greece has shown that organochlorine pesticides are present in the surface waters. Surface water samples have been collected seasonally from four rivers and five lakes for a period of two years. Solid-phase extraction followed by gas chromatographic techniques with electron capture detection was used for the determin...
Article
Full-text available
Data-based methods of flow forecasting are becoming increasingly popular due to their rapid development times, minimum information requirements, and ease of real-time implementation, with transfer function and artificial neural network methods the most commonly applied methods in practice. There is much antagonism between advocates of these two app...
Article
Northern Greece is a part of the country with great agricultural and industrial activity and the estimation of the pollution of its rivers and lakes is very important. The objective of this study is the determination of cadmium (Cd) in the surface waters of Northern Greece. The sampling period lasted 18 months, and samples were collected every 3 mo...
Article
Full-text available
A systems approach is used to describe the generation and variation of wastewater in an urban area. This is a multivariable system and its combined response at the outlet of this system, which is usually the entrance of a wastewater treatment plant, depends on a number of environmental (precipitation and temperature) as well as social (size of the...
Article
Full-text available
EXTENDED ABSTRACT Polycyclic Aromatic Hydrocarbons (PAHs) as well as nonylphenol (NP) and octylphenol (OP) are substances of major environmental interest because of their adverse health effects on organisms, including endocrine disrupting activity. Seven PAHs, NP and OP have been included in the priority list of substances regulated by 2000/60/EC W...
Article
Full-text available
An upgraded version of transfer function (TF) model was developed to analyse and forecast the behaviour of the river Pinios in Greece. The model utilises distributed rainfall information from several rain gauges together with upstream flow data and predicts the river flow at the Ali Efenti catchment outlet. In the work presented in this paper, a va...
Article
Full-text available
To support decisions and policy making, an econometric model has been developed that represents the cost structure of water supply and waste water treatment in an urban area. This paper proposes a method to capture the financial characteristics of the underlying organisation and addresses the steps and the conceptualisation in order to create a cos...

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Projects

Projects (8)
Project
The 17th International Conference on Environmental Science and Technology (CEST2021), will be held in Athens, Greece from 1 to 4 September 2021. The conference is organized by the Global Network of Environmental Science and Technology jointly with the University of the Aegean (Greece) and the National and Kapodistrian University of Athens (Greece). CEST2021 is academically supported by the University of Salerno (Italy), the University of Cincinnati (USA) and the Imperial College London (UK) as well as a group of distinguished scientists – the members of the Conference Scientific Committee. CEST2021 is under the patronage of UNESCO’s Water Assessment Programme, International Water Association (IWA), A.C. Laskaridis Charitable Foundation, and under the auspices of the Municipality of Athens. The non-governmental organization Prince Sultan Bin Abdulaziz International Prize for Water (PSIPW), is collaborating with CEST and offers travel grants to students and researchers from low-income countries. Established in 1989, the International Conference on Environmental Science and Technology (CEST) is a leading environmental conference where top experts, scientists, entrepreneurs, representatives of public administration, and social initiatives present state-of-the-art research on current and emerging environmental issues. The last (2019) event was successful, counting 420 participants from 81 countries originating from 6 continents (Europe, Asia, Africa, North America, South America, and Australia). The program included over 550 presentations (oral and poster) covering 28 unique research areas. Participants also benefited from the interaction with 25 distinguished invited speakers who delivered keynote and plenary talks. Conference thematic areas and topics CEST2021 topics will cover all the latest trends in Environmental Science and Technology as well as basic fields of research. The sessions are divided into nine thematic areas as follows: • Water and wastewater treatment and reuse • Hydrology and water resources • Waste management • Environmental management and policies • Environmental pollution • Ecology and ecosystem management • Analysis of environmental systems • Environmental health • Innovative environmental solutions More info, as well as registration and submission of paper, are available at https://www.cest2021.gnest.org/. Submit your paper by 23 April 2021.
Project
CEST2021, 1-4 September 2021, Athens, Greece ​ Established in 1989, the International Conference on Environmental Science and Technology (CEST) is a leading environmental conference where top experts, scientists, entrepreneurs, representatives of public administration and social initiatives present state-of-the-art research on current and emerging environmental issues. CEST is thus a platform where academia and business converge; where academic research, innovative ideas and solutions serve as the basis for a cleaner, healthier and more sustainable environment. ​ The conference is organized by the Global Network of Environmental Science and Technology jointly with the University of the Aegean (Greece) and the National and Kapodistrian University of Athens (Greece). CEST2021 is academically supported by the University of Salerno (Italy), the University of Cincinnati (USA) and the Imperial College London (UK) as well as a group of distinguished scientists – the members of the Conference Scientific Committee. ​ CEST2021 is under the patronage of UNESCO’s Water Assessment Programme, International Water Association (IWA), A.C. Laskaridis Charitable Foundation and under the auspices of the Municipality of Athens. The non-governmental organization Prince Sultan Bin Abdulaziz International Prize for Water (PSIPW), is collaborating with CEST and offers travel grants to students and researchers from low-income countries. ​ The event will be held in Athens from 1 to 4 September 2021. ​ The last (2019) event was successful, counting 420 participants from 81 countries originating from 6 continents (Europe, Asia, Africa, North America, South America and Australia). The programme included over 550 presentations (oral and poster) covering 28 unique research areas. Participants also benefited from the interaction with 25 distinguished invited speakers that delivered keynote and plenary talks. ​ Our conference is peer-reviewed. All the papers that are selected for either oral or poster presentation undergo a review process. CEST series proceedings have been included in databases, such as Science Citation Index (ISI) and since 2015, most of the presented papers are also published in cooperating journals - in special issues. ​ The papers from CEST2021 will been published in SPRINGER Proceedings.