Aristotelis Tegos

Civil Engineer, MSc, PhD candidate
tegosaris@yahoo.gr

Participation in research projects

Participation as Researcher

  1. Maintenance, upgrading and extension of the Decision Support System for the management of the Athens water resource system
  2. Flood risk estimation and forecast using hydrological models and probabilistic methods
  3. Investigation of management scenarios for the Smokovo reservoir

Participation in engineering studies

  1. Specific Technical Study for the Ecological Flow from the Dam of Stratos

Published work

Publications in scientific journals

  1. A. Tegos, H. Tyralis, D. Koutsoyiannis, and K. H. Hamed, An R function for the estimation of trend signifcance under the scaling hypothesis- application in PET parametric annual time series, Open Water Journal, 4 (1), 66–71, 6, 2017.
  2. H. Tyralis, A. Tegos, A. Delichatsiou, N. Mamassis, and D. Koutsoyiannis, A perpetually interrupted interbasin water transfer as a modern Greek drama: Assessing the Acheloos to Pinios interbasin water transfer in the context of integrated water resources management, Open Water Journal, 4 (1), 113–128, 12, 2017.
  3. P. Dimitriadis, A. Tegos, A. Oikonomou, V. Pagana, A. Koukouvinos, N. Mamassis, D. Koutsoyiannis, and A. Efstratiadis, Comparative evaluation of 1D and quasi-2D hydraulic models based on benchmark and real-world applications for uncertainty assessment in flood mapping, Journal of Hydrology, 534, 478–492, doi:10.1016/j.jhydrol.2016.01.020, 2016.
  4. A. Tegos, A. Efstratiadis, N. Malamos, N. Mamassis, and D. Koutsoyiannis, Evaluation of a parametric approach for estimating potential evapotranspiration across different climates, Agriculture and Agricultural Science Procedia, 4, 2–9, doi:10.1016/j.aaspro.2015.03.002, 2015.
  5. A. Tegos, N. Malamos, and D. Koutsoyiannis, A parsimonious regional parametric evapotranspiration model based on a simplification of the Penman-Monteith formula, Journal of Hydrology, 524, 708–717, doi:10.1016/j.jhydrol.2015.03.024, 2015.
  6. A. Efstratiadis, A. Tegos, A. Varveris, and D. Koutsoyiannis, Assessment of environmental flows under limited data availability – Case study of Acheloos River, Greece, Hydrological Sciences Journal, 59 (3-4), 731–750, doi:10.1080/02626667.2013.804625, 2014.
  7. D. Koutsoyiannis, N. Mamassis, and A. Tegos, Logical and illogical exegeses of hydrometeorological phenomena in ancient Greece, Water Science and Technology: Water Supply, 7 (1), 13–22, 2007.

Book chapters and fully evaluated conference publications

  1. N. Malamos, I. L. Tsirogiannis, A. Tegos, A. Efstratiadis, and D. Koutsoyiannis, Spatial interpolation of potential evapotranspiration for precision irrigation purposes, 10th World Congress on Water Resources and Environment, Athens, European Water Resources Association, 2017.
  2. A. Tegos, A. Efstratiadis, and D. Koutsoyiannis, A parametric model for potential evapotranspiration estimation based on a simplified formulation of the Penman-Monteith equation, Evapotranspiration - An Overview, edited by S. Alexandris, 143–165, doi:10.5772/52927, InTech, 2013.
  3. D. Koutsoyiannis, N. Mamassis, and A. Tegos, Logical and illogical exegeses of hydrometeorological phenomena in ancient Greece, Proceedings of the 1st IWA International Symposium on Water and Wastewater Technologies in Ancient Civilizations, edited by A. N. Angelakis and D. Koutsoyiannis, Iraklio, 135–143, doi:10.13140/RG.2.1.4188.4408, International Water Association, 2006.

Conference publications and presentations with evaluation of abstract

  1. N. Malamos, A. Tegos, I. L. Tsirogiannis, A. Christofides, and D. Koutsoyiannis, Implementation of a regional parametric model for potential evapotranspiration assessment, IrriMed 2015 – Modern technologies, strategies and tools for sustainable irrigation management and governance in Mediterranean agriculture, Bari, doi:10.13140/RG.2.1.3992.0725, 2015.
  2. A. Koukouvinos, D. Nikolopoulos, A. Efstratiadis, A. Tegos, E. Rozos, S.M. Papalexiou, P. Dimitriadis, Y. Markonis, P. Kossieris, H. Tyralis, G. Karakatsanis, K. Tzouka, A. Christofides, G. Karavokiros, A. Siskos, N. Mamassis, and D. Koutsoyiannis, Integrated water and renewable energy management: the Acheloos-Peneios region case study, European Geosciences Union General Assembly 2015, Geophysical Research Abstracts, Vol. 17, Vienna, EGU2015-4912, doi:10.13140/RG.2.2.17726.69440, European Geosciences Union, 2015.
  3. A. Tegos, A. Efstratiadis, N. Malamos, N. Mamassis, and D. Koutsoyiannis, Evaluation of a parametric approach for estimating potential evapotranspiration across different climates, IRLA2014 – The Effects of Irrigation and Drainage on Rural and Urban Landscapes, Patras, doi:10.13140/RG.2.2.14004.24966, 2014.
  4. N. Bountas, N. Boboti, E. Feloni, L. Zeikos, Y. Markonis, A. Tegos, N. Mamassis, and D. Koutsoyiannis, Temperature variability over Greece: Links between space and time, Facets of Uncertainty: 5th EGU Leonardo Conference – Hydrofractals 2013 – STAHY 2013, Kos Island, Greece, doi:10.13140/RG.2.2.17739.80164, European Geosciences Union, International Association of Hydrological Sciences, International Union of Geodesy and Geophysics, 2013.
  5. A. Efstratiadis, A. Koukouvinos, P. Dimitriadis, A. Tegos, N. Mamassis, and D. Koutsoyiannis, A stochastic simulation framework for flood engineering, Facets of Uncertainty: 5th EGU Leonardo Conference – Hydrofractals 2013 – STAHY 2013, Kos Island, Greece, doi:10.13140/RG.2.2.16848.51201, European Geosciences Union, International Association of Hydrological Sciences, International Union of Geodesy and Geophysics, 2013.
  6. V. Pagana, A. Tegos, P. Dimitriadis, A. Koukouvinos, P. Panagopoulos, and N. Mamassis, Alternative methods in floodplain hydraulic simulation - Experiences and perspectives, European Geosciences Union General Assembly 2013, Geophysical Research Abstracts, Vol. 15, Vienna, EGU2013-10283-2, European Geosciences Union, 2013.
  7. A. Oikonomou, P. Dimitriadis, A. Koukouvinos, A. Tegos, V. Pagana, P. Panagopoulos, N. Mamassis, and D. Koutsoyiannis, Floodplain mapping via 1D and quasi-2D numerical models in the valley of Thessaly, Greece, European Geosciences Union General Assembly 2013, Geophysical Research Abstracts, Vol. 15, Vienna, EGU2013-10366, doi:10.13140/RG.2.2.25165.03040, European Geosciences Union, 2013.
  8. A. Varveris, P. Panagopoulos, K. Triantafillou, A. Tegos, A. Efstratiadis, N. Mamassis, and D. Koutsoyiannis, Assessment of environmental flows of Acheloos Delta, European Geosciences Union General Assembly 2010, Geophysical Research Abstracts, Vol. 12, Vienna, 12046, doi:10.13140/RG.2.2.14849.66404, European Geosciences Union, 2010.
  9. A. Tegos, N. Mamassis, and D. Koutsoyiannis, Estimation of potential evapotranspiration with minimal data dependence, European Geosciences Union General Assembly 2009, Geophysical Research Abstracts, Vol. 11, Vienna, 1937, doi:10.13140/RG.2.2.27222.86089, European Geosciences Union, 2009.
  10. A. Efstratiadis, A. Tegos, I. Nalbantis, E. Rozos, A. Koukouvinos, N. Mamassis, S.M. Papalexiou, and D. Koutsoyiannis, Hydrogeios, an integrated model for simulating complex hydrographic networks - A case study to West Thessaly region, 7th Plinius Conference on Mediterranean Storms, Rethymnon, Crete, doi:10.13140/RG.2.2.25781.06881, European Geosciences Union, 2005.

Presentations and publications in workshops

  1. A. Tegos, A. Efstratiadis, A. Varveris, N. Mamassis, A. Koukouvinos, and D. Koutsoyiannis, Assesment and implementation of ecological flow constraints in large hydroelectric works: The case of Acheloos, Ecological flow of rivers and the importance of their true assesment, 2014.
  2. D. Koutsoyiannis, N. Mamassis, and A. Tegos, Hydrometeorological issues in ancient Greek science and philosophy, The Eco-nomy of Water, edited by E Efthymiopoulos and M. Modinos, Hydra island, doi:10.13140/RG.2.2.25574.63040, Hellenica Grammata, 2009.

Various publications

  1. A. Tegos, Acheloos, 2009.
  2. A. Tegos, Acheloos: Does the water belong only to fish?, March 2009.

Academic works

  1. A. Tegos, Simplification of evapotranspiration estimation in Greece, Postgraduate Thesis, Department of Water Resources and Environmental Engineering – National Technical University of Athens, Athens, 2007.
  2. A. Tegos, Combined simultation of hydrological-hydrogeological processes and operation of Western Thessaly hydrosystem, Diploma thesis, 132 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, September 2005.

Research reports

  1. A. Koukouvinos, A. Efstratiadis, D. Nikolopoulos, H. Tyralis, A. Tegos, N. Mamassis, and D. Koutsoyiannis, Case study in the Acheloos-Thessaly system, Combined REnewable Systems for Sustainable ENergy DevelOpment (CRESSENDO), 98 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, October 2015.
  2. N. Mamassis, R. Mavrodimou, A. Efstratiadis, M. Heidarlis, A. Tegos, A. Koukouvinos, P. Lazaridou, M. Magaliou, and D. Koutsoyiannis, Investigation of alternative organisations and operations of a Water Management Body for the Smokovo projects, Investigation of management scenarios for the Smokovo reservoir, Report 2, 73 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, March 2007.
  3. A. Efstratiadis, A. Tegos, G. Karavokiros, I. Kyriazopoulou, and I. Vazimas, Master Plan for water resources management for the area of Karditsa, Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS), Report 16, 132 pages, NAMA, Athens, December 2006.
  4. A. Efstratiadis, A. Koukouvinos, E. Rozos, A. Tegos, and I. Nalbantis, Theoretical documentation of model for simulating hydrological-hydrogeological processes of river basin "Hydrogeios", Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS), Contractor: NAMA, Report 4a, 103 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, December 2006.

Details on research projects

Participation as Researcher

  1. Maintenance, upgrading and extension of the Decision Support System for the management of the Athens water resource system

    Duration: October 2008–November 2011

    Budget: €72 000

    Project director: N. Mamassis

    Principal investigator: D. Koutsoyiannis

    This research project includes the maintenance, upgrading and extension of the Decision Support System that developed by NTUA for EYDAP in the framework of the research project “Updating of the supervision and management of the water resources’ system for the water supply of the Athens’ metropolitan area”. The project is consisted of the following parts: (a) Upgrading of the Data Base, (b)Upgrading and extension of hydrometeorological network, (c) upgrading of the hydrometeorological data process software, (d) upgrading and extension of the Hydronomeas software, (e) hydrological data analysis and (f) support to the preparation of the annual master plans

  1. Flood risk estimation and forecast using hydrological models and probabilistic methods

    Duration: February 2007–August 2008

    Budget: €15 000

    Commissioned by: National Technical University of Athens

    Contractor: Department of Water Resources and Environmental Engineering

    Collaborators: Hydrologic Research Center

    Project director: D. Koutsoyiannis

    Principal investigator: S.M. Papalexiou

    Programme: Πρόγραμμα Βασικής Έρευνας ΕΜΠ "Κωνσταντίνος Καραθεοδωρή"

    The objective of this project is the development of an integrated framework for the estimation and forecast of flood risk using stochastic, hydrological and hydraulics methods. The study area is the Boeticos Kephisos river basin. The project includes analysis of severe storm episodes in the basin, the understanding of mechanisms of flood generation in this karstic basin and the estimation of flood risk in characteristic sites of the hydrosystem.

  1. Investigation of management scenarios for the Smokovo reservoir

    Duration: November 2005–December 2006

    Budget: €60 000

    Commissioned by: Special Directorate for the Management of Corporate Programs of Thessaly

    Contractor: Department of Water Resources, Hydraulic and Maritime Engineering

    Project director: D. Koutsoyiannis

    Principal investigator: N. Mamassis

    Programme: Επιχειρησιακά Σχέδια Διαχείρισης Δικτύων Σμοκόβου

Details on engineering studies

  1. Specific Technical Study for the Ecological Flow from the Dam of Stratos

    Duration: January 2009–June 2009

    Commissioned by: Public Power Corporation

    Contractor: ECOS Consultants S.A.

Published work in detail

Publications in scientific journals

  1. A. Tegos, H. Tyralis, D. Koutsoyiannis, and K. H. Hamed, An R function for the estimation of trend signifcance under the scaling hypothesis- application in PET parametric annual time series, Open Water Journal, 4 (1), 66–71, 6, 2017.

    We present an R function for testing the significant trend of time series. Te function calculates trend significance using a modified Mann-Kendall test, which takes into account the well-known physical behavior of the Hurst-Kolmogorov dynamics. Te function is tested at 10 stations in Greece, with approximately 50 years of PET data with the use of a recent parametric approach. A significant downward trend was detected at two stations. Te R software is now suitable for extensive use in several fields of the scientific community, allowing a physical consistent of a trend analysis.

    Full text: http://www.itia.ntua.gr/en/getfile/1703/1/documents/2017OW_An_R_FunctionForTrendSignificance.pdf (326 KB)

    Additional material:

    See also: http://scholarsarchive.byu.edu/openwater/vol4/iss1/6/

  1. H. Tyralis, A. Tegos, A. Delichatsiou, N. Mamassis, and D. Koutsoyiannis, A perpetually interrupted interbasin water transfer as a modern Greek drama: Assessing the Acheloos to Pinios interbasin water transfer in the context of integrated water resources management, Open Water Journal, 4 (1), 113–128, 12, 2017.

    Interbasin water transfer is a primary instrument of water resources management directly related with the integrated development of the economy, society and environment. Here we assess the project of the interbasin water transfer from the river Acheloos to the river Pinios basin which has intrigued the Greek society, the politicians and scientists for decades. Te set of criteria we apply originate from a previous study reviewing four interbasin water transfers and assessing whether an interbasin water transfer is compatible with the concept of integrated water resources management. In this respect, we assess which of the principles of the integrated water resources management the Acheloos to Pinios interbasin water transfer project does or does not satisfy. While the project meets the criteria of real surplus and deficit, of sustainability and of sound science, i.e., the criteria mostly related to the engineering part, it fails to meet the criteria of good governance and balancing of existing rights with needs, i.e., the criteria associated with social aspects of the project. Te non-fulfillment of the latter criteria is the consequence of chronic diseases of the Greek society, which become obvious in the case study

    Full text: http://www.itia.ntua.gr/en/getfile/1702/1/documents/2017OW_AcheloosToPiniosInterbasinWaterTransfer.pdf (2744 KB)

    See also: http://scholarsarchive.byu.edu/openwater/vol4/iss1/11/

  1. P. Dimitriadis, A. Tegos, A. Oikonomou, V. Pagana, A. Koukouvinos, N. Mamassis, D. Koutsoyiannis, and A. Efstratiadis, Comparative evaluation of 1D and quasi-2D hydraulic models based on benchmark and real-world applications for uncertainty assessment in flood mapping, Journal of Hydrology, 534, 478–492, doi:10.1016/j.jhydrol.2016.01.020, 2016.

    One-dimensional and quasi-two-dimensional hydraulic freeware models (HEC-RAS, LISFLOOD-FP and FLO-2d) are widely used for flood inundation mapping. These models are tested on a benchmark test with a mixed rectangular-triangular channel cross section. Using a Monte-Carlo approach, we employ extended sensitivity analysis by simultaneously varying the input discharge, longitudinal and lateral gradients and roughness coefficients, as well as the grid cell size. Based on statistical analysis of three output variables of interest, i.e. water depths at the inflow and outflow locations and total flood volume, we investigate the uncertainty enclosed in different model configurations and flow conditions, without the influence of errors and other assumptions on topography, channel geometry and boundary conditions. Moreover, we estimate the uncertainty associated to each input variable and we compare it to the overall one. The outcomes of the benchmark analysis are further highlighted by applying the three models to real-world flood propagation problems, in the context of two challenging case studies in Greece.

    Other works that reference this work (this list might be obsolete):

    1. Apel, H., O. Martínez Trepat, N. N. Hung, D. T. Chinh, B. Merz, and N. V. Dung, Combined fluvial and pluvial urban flood hazard analysis: concept development and application to Can Tho city, Mekong Delta, Vietnam, Natural Hazards and Earth System Sciences, 16, 941-961, doi:10.5194/nhess-16-941-2016, 2016.
    2. Papaioannou , G., A. Loukas, L. Vasiliades, and G. T. Aronica, Flood inundation mapping sensitivity to riverine spatial resolution and modelling approach, Natural Hazards, 83, 117-132, doi:10.1007/s11069-016-2382-1, 2016.
    3. #Santillan, J. R., A. M. Amora, M. Makinano-Santillan, J. T. Marqueso, L. C. Cutamora, J. L. Serviano, and R. M. Makinano, Assessing the impacts of flooding caused by extreme rainfall events through a combined geospatial and numerical modeling approach, The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. XLI-B8, 2016, XXIII ISPRS Congress, Prague, doi:10.5194/isprs-archives-XLI-B8-1271-2016, 2016.
    4. Cheviron, B. and R. Moussa, Determinants of modelling choices for 1-D free-surface flow and morphodynamics in hydrology and hydraulics: a review, Hydrology and Earth System Sciences, 20, 3799-3830, doi:10.5194/hess-20-3799-2016, 2016.
    5. Mohd Talha Anees, K. Abdullah, M.N.M. Nawawi, Nik Norulaini Nik Ab Rahman, Abd. Rahni Mt. Piah, Nor Azazi Zakaria, M.I. Syakir, and A.K. Mohd. Omar, Numerical modeling techniques for flood analysis, Journal of African Earth Sciences, 124, 478–486, doi:10.1016/j.jafrearsci.2016.10.001, 2016.
    6. Skublics, D., G. Blöschl, and P. Rutschmann, Effect of river training on flood retention of the Bavarian Danube, Journal of Hydrology and Hydromechanics, 64(4), 349-356, doi:10.1515/johh-2016-0035, 2016.
    7. Doong, D.-J., W. Lo, Z. Vojinovic, W.-L. Lee, and S.-P. Lee, Development of a new generation of flood inundation maps—A case study of the coastal City of Tainan, Taiwan, Water, 8(11), 521, doi:10.3390/w8110521, 2016.
    8. #Cartaya, S., and R. Mantuano-Eduarte, Identificación de zonas en riesgo de inundación mediante la simulación hidráulica en un segmento del Río Pescadillo, Manabí, Ecuador, Revista de Investigación, 40(89), 158-170, 2016.
    9. Javadnejad, F., B. Waldron, and A. Hill, LITE Flood: Simple GIS-based mapping approach for real-time redelineation of multifrequency floods, Natural Hazards Review, doi:10.1061/(ASCE)NH.1527-6996.0000238, 2017.
    10. Shrestha, A., M. S. Babel, S. Weesakul, and Z. Vojinovic, Developing intensity–duration–frequency (IDF) curves under climate change uncertainty: The case of Bangkok, Thailand, Water, 9(2), 145, doi:10.3390/w9020145, 2017.
    11. Roushangar, K., M. T. Alami, V. Nourani, and A. Nouri, A cost model with several hydraulic constraints for optimizing in practice a trapezoidal cross section, Journal of Hydroinformatics, 19(3), 456-468, doi:10.2166/hydro.2017.081, 2017.
    12. Papaioannou, G., L. Vasiliades, A. Loukas, and G. T. Aronica, Probabilistic flood inundation mapping at ungauged streams due to roughness coefficient uncertainty in hydraulic modelling, Advances in Geosciences, 44, 23-34, doi:10.5194/adgeo-44-23-2017, 2017.

  1. A. Tegos, A. Efstratiadis, N. Malamos, N. Mamassis, and D. Koutsoyiannis, Evaluation of a parametric approach for estimating potential evapotranspiration across different climates, Agriculture and Agricultural Science Procedia, 4, 2–9, doi:10.1016/j.aaspro.2015.03.002, 2015.

    Potential evapotranspiration (PET) is key input in water resources, agricultural and environmental modelling. For many decades, numerous approaches have been proposed for the consistent estimation of PET at several time scales of interest. The most recognized is the Penman-Monteith formula, which is yet difficult to apply in data-scarce areas, since it requires simultaneous observations of four meteorological variables (temperature, sunshine duration, humidity, wind velocity). For this reason, parsimonious models with minimum input data requirements are strongly preferred. Typically, these have been developed and tested for specific hydroclimatic conditions, but when they are applied in different regimes they provide much less reliable (and in some cases misleading) estimates. Therefore, it is essential to develop generic methods that remain parsimonious, in terms of input data and parameterization, yet they also allow for some kind of local adjustment of their parameters, through calibration. In this study we present a recent parametric formula, based on a simplified formulation of the original Penman-Monteith expression, which only requires mean daily or monthly temperature data. The method is evaluated using meteorological records from different areas worldwide, at both the daily and monthly time scales. The outcomes of this extended analysis are very encouraging, as indicated by the substantially high validation scores of the proposed approach across all examined data sets. In general, the parametric model outperforms well-established methods of the everyday practice, since it ensures optimal approximation of potential evapotranspiration.

    Full text: http://www.itia.ntua.gr/en/getfile/1549/1/documents/IRLA_paper.pdf (560 KB)

    See also: http://dx.doi.org/10.1016/j.aaspro.2015.03.002

    Other works that reference this work (this list might be obsolete):

    1. Stan, F.I., G. Neculau, L. Zaharia, G. Ioana-Toroimac, and S. Mihalache, Study on the evaporation and evapotranspiration measured on the Căldăruşani Lake (Romania), Procedia Environmental Sciences, 32, 281–289, doi:10.1016/j.proenv.2016.03.033, 2016.
    2. Esquivel-Hernández, G., R. Sánchez-Murillo, C. Birkel, S. P. Good, and J. Boll, Hydro-climatic and ecohydrological resistance/resilience conditions across tropical biomes of Costa Rica, Ecohydrology, doi:10.1002/eco.1860, 2017.

  1. A. Tegos, N. Malamos, and D. Koutsoyiannis, A parsimonious regional parametric evapotranspiration model based on a simplification of the Penman-Monteith formula, Journal of Hydrology, 524, 708–717, doi:10.1016/j.jhydrol.2015.03.024, 2015.

    Evapotranspiration is a key hydrometeorological process and its estimation is important in many fields of hydrological and agricultural sciences. Simplified estimation proves very useful in absence of a complete data set. In this respect, a parametric model based on simplification of the Penman-Monteith formulation is presented. The basic idea of the parametric model is the replacement of some of the variables and constants that are used in the standard Penman-Monteith model by regionally varying parameters, which are estimated through calibration. The model is implemented in various climates on monthly time step (USA, Germany, Spain) and compared on the same basis with four radiation-based methods (Jensen-Haise, McGuiness and Bordne, Hargreaves and Oudin) and two temperature-based (Thornthwaite and Blaney-Criddle). The methodology yields very good results with high efficiency indexes, outperforming the other models. Finally, a spatial analysis including the correlation of parameters with latitude and elevation together with their regionalization through three common spatial interpolation techniques along with a recent approach (Bilinear Surface Smoothing), is performed. Also, the model is validated against Penman-Monteith estimates in eleven stations of the well-known CIMIS network. The total framework which includes the development, the implementation, the comparison and the mapping of parameters illustrates a new parsimonious and high efficiency methodology in the assessment of potential evapotranspiration field.

    Additional material:

    See also: http://dx.doi.org/10.1016/j.jhydrol.2015.03.024

  1. A. Efstratiadis, A. Tegos, A. Varveris, and D. Koutsoyiannis, Assessment of environmental flows under limited data availability – Case study of Acheloos River, Greece, Hydrological Sciences Journal, 59 (3-4), 731–750, doi:10.1080/02626667.2013.804625, 2014.

    The lower course of Acheloos River is an important hydrosystem of Greece, heavily modified by a cascade of four hydropower dams, which is now being extended by two more dams in the upper course. The design of the dams and hydropower facilities that are in operation has not considered any environmental criteria. However, in the last fifty years, numerous methodologies have been proposed to assess the negative impacts of such projects to both the abiotic and biotic environment, and to provide decision support towards establishing appropriate constraints on their operation, typically in terms of minimum flow requirements. In this study, seeking for a more environmental-friendly operation of the hydrosystem, we investigate the outflow policy from the most downstream dam, examining alternative environmental flow approaches. Accounting for data limitations, we recommend the Basic Flow Method, which is parsimonious and suitable for Mediterranean rivers, whose flows exhibit strong variability across seasons. We also show that the wetted perimeter – discharge method, which is an elementary hydraulic approach, provides consistent results, even without using any flow data. Finally, we examine the adaptation of the proposed flow policy (including artificial flooding) to the real-time hydropower generation schedule, and the management of the resulting conflicts.

    Additional material:

    See also: http://dx.doi.org/10.1080/02626667.2013.804625

    Other works that reference this work (this list might be obsolete):

    1. Acreman, M. C., I. C. Overton, J. King, P. Wood, I. G. Cowx, M. J. Dunbar, E. Kendy, and W. Young, The changing role of ecohydrological science in guiding environmental flows, Hydrological Sciences Journal, 59(3–4), 1–18, 2014.
    2. #Egüen, M., M. J. Polo, Z. Gulliver, E. Contreras, C. Aguilar, and M. A. Losada, Flood risk trends in coastal watersheds in South Spain: direct and indirect impact of river regulation, Changes in Flood Risk and Perception in Catchments and Cities, Proc. IAHS, 370, 51-56, doi:10.5194/piahs-370-51-2015, 2015.
    3. Aguilar, C., and M. J. Polo, Assessing minimum environmental flows in nonpermanent rivers: The choice of thresholds, Environmental Modelling and Software, 79, 120-134, doi:10.1016/j.envsoft.2016.02.003, 2016.
    4. Nerantzaki, S. D., G. V. Giannakis, N. P. Nikolaidis, I. Zacharias, G. P. Karatzas, and I. A. Sibetheros, Assessing the impact of climate change on sediment loads in a large Mediterranean watershed, Soil Science, 181(7), 306-314, 2016.
    5. Poncelet, C., V. Andréassian, L. Oudin, and C. Perrin, The Quantile Solidarity approach for the parsimonious regionalization of flow duration curves, Hydrological Sciences Journal, doi:10.1080/02626667.2017.1335399, 2017.

  1. D. Koutsoyiannis, N. Mamassis, and A. Tegos, Logical and illogical exegeses of hydrometeorological phenomena in ancient Greece, Water Science and Technology: Water Supply, 7 (1), 13–22, 2007.

    Technological applications aiming at the exploitation of the natural sources appear in all ancient civilizations. The unique phenomenon in the ancient Greek civilization is that technological needs triggered physical explanations of natural phenomena, thus enabling the foundation of philosophy and science. Among these, the study of hydrometeorological phenomena had a major role. This study begins with the Ionian philosophers in the seventh century BC, continues in classical Athens in the fifth and fourth centuries BC, and advances and expands through the entire Greek world up to the end of Hellenistic period. Many of the theories developed by ancient Greeks are erroneous according to modern views. However, many elements in Greek exegeses of hydrometeorological processes, such as evaporation and condensation of vapour, creation of clouds, hail, snow and rainfall, and evolution of hydrological cycle, are impressive even today.

    Related works:

    • [22] Translation into Greek

    Additional material:

    See also: http://dx.doi.org/10.2166/ws.2007.002

    Other works that reference this work (this list might be obsolete):

    1. Mays, L.W., A very brief history of hydraulic technology during antiquity, Environmental Fluid Mechanics, 8 (5-6), 471-484, 2008.
    2. Angelakis, A. N., and D. S. Spyridakis, A brief history of water supply and wastewater management in ancient Greece, Water Science and Technology: Water Supply, 10 (4), 618-628, 2010.
    3. #Angelakis, A. N., E. G. Dialynas and V. Despotakis, Evolution of water supply technologies through the centuries in Crete, Greece, Ch. 9 in Evolution of Water Supply Through the Millennia (A. N. Angelakis, L. W. Mays, D. Koutsoyiannis and N. Mamassis, eds.), 227-258, IWA Publishing, London, 2012.

Book chapters and fully evaluated conference publications

  1. N. Malamos, I. L. Tsirogiannis, A. Tegos, A. Efstratiadis, and D. Koutsoyiannis, Spatial interpolation of potential evapotranspiration for precision irrigation purposes, 10th World Congress on Water Resources and Environment, Athens, European Water Resources Association, 2017.

    Precision irrigation constitutes a breakthrough for agricultural water management since it provides means to optimal water use. In recent years several applications of precision irrigation are implemented based on spatial data from different origins, i.e. meteorological stations networks, remote sensing data and in situ measurements. One of the factors affecting optimal irrigation system design and management is the daily potential evapotranspiration (PET). A commonly used approach is to estimate the daily PET for the representative day of each month during the irrigation period. In the present study, the implementation of the recently introduced non-parametric bilinear surface smoothing (BSS) methodology for spatial interpolation of daily PET is presented. The study area was the plain of Arta which is located at the Region of Epirus at the North West Greece. Daily PET was estimated according to the FAO Penman-Monteith methodology with data collected from a network of six agrometeorological stations, installed in early 2015 in selected locations throughout the study area. For exploration purposes, we produced PET maps for the Julian dates: 105, 135, 162, 199, 229 and 259, thus covering the entire irrigation period of 2015. Also, comparison and cross validation against the calculated FAO Penman-Monteith PET for each station, were performed between BSS and a commonly used interpolation method, i.e. inverse distance weighted (IDW). During the leave-one-out cross validation procedure, BSS yielded very good results, outperforming IDW. Given the simplicity of the BSS, its overall performance is satisfactory, providing maps that represent the spatial and temporal variation of daily PET.

  1. A. Tegos, A. Efstratiadis, and D. Koutsoyiannis, A parametric model for potential evapotranspiration estimation based on a simplified formulation of the Penman-Monteith equation, Evapotranspiration - An Overview, edited by S. Alexandris, 143–165, doi:10.5772/52927, InTech, 2013.

    Full text: http://www.itia.ntua.gr/en/getfile/1284/1/documents/2013InTech_ParametricModelPET.pdf (819 KB)

    See also: http://dx.doi.org/10.5772/52927

    Other works that reference this work (this list might be obsolete):

    1. Samaras, D. A., A. Reif and K. Theodoropoulos, Evaluation of radiation-based reference evapotranspiration models under different Mediterranean climates in Central Greece, Water Resources Management, 28 (1), 207-225, 2014.
    2. Tabari, H., P. H. Talaee, P. Willems, and C. Martinez, Validation and calibration of solar radiation equations for estimating daily reference evapotranspiration at cool semi-arid and arid locations, Hydrological Sciences Journal, 61(3), 610-619, doi:10.1080/02626667.2014.947293, 2016.
    3. Jaber, H. S., S. Mansor, B. Pradhan, and N. Ahmad, Evaluation of SEBAL model for evapotranspiration mapping in Iraq using remote sensing and GIS, International Journal of Applied Engineering Research, 11(6), 3950-3955, 2016.
    4. Kumar, D., J. Adamowski, R. Suresh, and B. Ozga-Zielinski, Estimating evapotranspiration using an extreme learning machine model: case study in North Bihar, India, Journal of Irrigation and Drainage Engineering, 04016032, doi:10.1061/(ASCE)IR.1943-4774.0001044, 2016.
    5. Djaman, K., D. Rudnick, V. C. Mel, and D. Mutiibwa, Evaluation of Valiantzas’ simplified forms of the FAO-56 Penman-Monteith reference evapotranspiration model in a humid climate, Journal of Irrigation and Drainage Engineering, doi:10.1061/(ASCE)IR.1943-4774.0001191, 2017.

  1. D. Koutsoyiannis, N. Mamassis, and A. Tegos, Logical and illogical exegeses of hydrometeorological phenomena in ancient Greece, Proceedings of the 1st IWA International Symposium on Water and Wastewater Technologies in Ancient Civilizations, edited by A. N. Angelakis and D. Koutsoyiannis, Iraklio, 135–143, doi:10.13140/RG.2.1.4188.4408, International Water Association, 2006.

    Technological applications aiming at the exploitation of the natural sources appear in all ancient civilizations. The unique phenomenon in the ancient Greek civilization is that technological needs triggered physical explanations of the natural phenomena and behaviours, thus enabling the foundation of philosophy and science. Among these, the study of hydrometeorological phenomena had a major role. This study begins with the Ionian philosophers in the seventh century BC, continues in classical Athens in the fifth and fourth centuries BC, and advances and expands through the entire Greek world up to the end of Hellenistic period, when Romans conquered Greece. Many of the theories developed in the course of ancient Greek civilization are erroneous according to modern views. However, many elements in Greek exegeses and interpretations of various hydrometeorological processes, such as the evaporation and condensation of vapour, the creation of clouds, hail, snow and rainfall and the evolution of hydrological cycle, are impressive even today.

    Related works:

    • [7] Revised version of the same article.

    Full text:

    See also: http://dx.doi.org/10.13140/RG.2.1.4188.4408

Conference publications and presentations with evaluation of abstract

  1. N. Malamos, A. Tegos, I. L. Tsirogiannis, A. Christofides, and D. Koutsoyiannis, Implementation of a regional parametric model for potential evapotranspiration assessment, IrriMed 2015 – Modern technologies, strategies and tools for sustainable irrigation management and governance in Mediterranean agriculture, Bari, doi:10.13140/RG.2.1.3992.0725, 2015.

    Potential evapotranspiration (PET) is key input in water resources, agricultural and environmental modelling. For many decades, several approaches have been proposed for the consistent estimation of PET at several time scales of interest. The most recognized is the Penman‐Monteith formula, which is yet difficult to apply, since it requires simultaneous measurements of four meteorological variables (temperature, sunshine duration, humidity, wind velocity). For this reason, simplified approaches prove very useful in absence of a complete data set and are strongly preferred. In the present study, we implement a recent parametric formula to model PET in the Arta plain, located in the Region of Epirus ‐ Greece, which is based on a simplified formulation of the original Penman‐Monteith expression and requires only mean hourly, daily or monthly temperature data, depending on the desired time step. The methodology is generic, yet parsimonious in terms of the input data, with its parameters adjusted through calibration, to the available PET data. A spatial analysis concerning the regionalization of the parameters and PET estimates of the proposed methodology by implementing interpolation techniques is performed. The results are very satisfactory, illustrating that the proposed framework is efficient and constitutes a reliable alternative in the assessment of potential evapotranspiration field

    Full text: http://www.itia.ntua.gr/en/getfile/1576/1/documents/2015Bari_Implementation_of_a_regional_parametric.pdf (2372 KB)

    See also: http://dx.doi.org/10.13140/RG.2.1.3992.0725

  1. A. Koukouvinos, D. Nikolopoulos, A. Efstratiadis, A. Tegos, E. Rozos, S.M. Papalexiou, P. Dimitriadis, Y. Markonis, P. Kossieris, H. Tyralis, G. Karakatsanis, K. Tzouka, A. Christofides, G. Karavokiros, A. Siskos, N. Mamassis, and D. Koutsoyiannis, Integrated water and renewable energy management: the Acheloos-Peneios region case study, European Geosciences Union General Assembly 2015, Geophysical Research Abstracts, Vol. 17, Vienna, EGU2015-4912, doi:10.13140/RG.2.2.17726.69440, European Geosciences Union, 2015.

    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 tested in two major adjacent river basins in Greece (Acheloos, Peneios) extending over 15 500 km2 (12% of Greek territory). River Acheloos is characterized by very high runoff and holds ~40% of the installed hydropower capacity of Greece. On the other hand, the Thessaly plain drained by Peneios – a key agricultural region for the national economy – usually suffers from water scarcity and systematic environmental degradation. The two basins are interconnected through diversion projects, existing and planned, thus formulating a unique large-scale hydrosystem whose future has been the subject of a great controversy. The study area is viewed as a hypothetically closed, energy-autonomous, system, in order to evaluate the perspectives for sustainable development of its water and energy resources. In this context we seek an efficient configuration of the necessary hydraulic and renewable energy projects through integrated modelling of the water and energy balance. We investigate several scenarios of energy demand for domestic, industrial and agricultural use, assuming that part of the demand is fulfilled via wind and solar energy, while the excess or deficit of energy is regulated through large hydroelectric works that are equipped with pumping storage facilities. The overall goal is to examine under which conditions a fully renewable energy system can be technically and economically viable for such large spatial scale.

    Full text:

    Additional material:

    See also: http://dx.doi.org/10.13140/RG.2.2.17726.69440

  1. A. Tegos, A. Efstratiadis, N. Malamos, N. Mamassis, and D. Koutsoyiannis, Evaluation of a parametric approach for estimating potential evapotranspiration across different climates, IRLA2014 – The Effects of Irrigation and Drainage on Rural and Urban Landscapes, Patras, doi:10.13140/RG.2.2.14004.24966, 2014.

    Potential evapotranspiration (PET) is key input in water resources, agricultural and environmental modelling. For many decades, numerous approaches have been proposed for the consistent estimation of PET at several time scales of interest. The most recognized is the Penman-Monteith formula, which is yet difficult to apply in data-scarce areas, since it requires simultaneous observations of four meteorological variables (temperature, sunshine duration, humidity, wind velocity). For this reason, parsimonious models with minimum input data requirements are strongly preferred. Typically, these have been developed and tested for specific hydroclimatic conditions, but when they are applied in different regimes they provide much less reliable (and in some cases misleading) estimates. Therefore, it is essential to develop generic methods that remain parsimonious, in terms of input data and parameterization, yet they also allow for some kind of local adjustment of their parameters, through calibration. In this study we present a recent parametric formula, based on a simplified formulation of the original Penman-Monteith expression, which only requires mean daily or monthly temperature data. The method is evaluated using meteorological records from different areas worldwide, at both the daily and monthly time scales. The outcomes of this extended analysis are very encouraging, as indicated by the substantially high validation scores of the proposed approach across all examined data sets. In general, the parametric model outperforms well-established methods of the everyday practice, since it ensures optimal approximation of PET.

    Full text: http://www.itia.ntua.gr/en/getfile/1512/1/documents/2014_IRLA_Parametric.pdf (740 KB)

    See also: http://dx.doi.org/10.13140/RG.2.2.14004.24966

  1. N. Bountas, N. Boboti, E. Feloni, L. Zeikos, Y. Markonis, A. Tegos, N. Mamassis, and D. Koutsoyiannis, Temperature variability over Greece: Links between space and time, Facets of Uncertainty: 5th EGU Leonardo Conference – Hydrofractals 2013 – STAHY 2013, Kos Island, Greece, doi:10.13140/RG.2.2.17739.80164, European Geosciences Union, International Association of Hydrological Sciences, International Union of Geodesy and Geophysics, 2013.

    Temperature is strongly linked to the hydrological cycle in numerous ways and mainly with the evapotranspiration. Our aim here is to examine the possible influence of spatial characteristics on the temperature temporal variability of the monthly absolute maxima/minima and the monthly means over Greece. To achieve this, the temperature records of the Hellenic National Meteorological Service station network, which date back to 1950, are analysed. The analysis involved two steps: the determination of regions with similar climatic properties and the investigation of the possible correlations of temperature in time. Thus, the time series are classified in three groups based on their location (continental, coastal and island) and four types regarding the proximity of the station to a city (at the city centre, near the city border, far away from city border) or to an airport. Each one of the time series is then examined for (a) the influence of the city heat island as Greek cities expanded in time, (b) the effect of the general atmospheric circulation (NAO phase), (c) its correlation to the global temperature record and (d) the implied change on evapotranspiration in the area.

    Full text: http://www.itia.ntua.gr/en/getfile/1391/1/documents/Kos_Temperature_poster_.pdf (2010 KB)

    See also: http://dx.doi.org/10.13140/RG.2.2.17739.80164

  1. A. Efstratiadis, A. Koukouvinos, P. Dimitriadis, A. Tegos, N. Mamassis, and D. Koutsoyiannis, A stochastic simulation framework for flood engineering, Facets of Uncertainty: 5th EGU Leonardo Conference – Hydrofractals 2013 – STAHY 2013, Kos Island, Greece, doi:10.13140/RG.2.2.16848.51201, European Geosciences Union, International Association of Hydrological Sciences, International Union of Geodesy and Geophysics, 2013.

    Flood engineering is typically tackled as a sequential application of formulas and models, with specific assumptions and parameter values, thus providing fully deterministic outputs. In this procedure, the unique probabilistic concept is the return period of rainfall, which is set a priori, to represent the acceptable risk of all design variables of interest (peak flows, flood hydrographs, flow depths and velocities, inundated areas, etc.). Yet, a more consistent approach would require estimating the risks by integrating the uncertainties of all individual variables. This option can be offered by stochastic simulation, which is the most effective and powerful technique for analysing systems of high complexity and uncertainty. This presupposes to recognize which of the modelling components represent time-varying processes and which ones represent unknown, thus uncertain, parameters. In the proposed framework both should be handled as random variables. The following computational steps are envisaged: (a) generation of synthetic time series of areal rainfall, through multivariate stochastic disaggregation models; (b) generation of random sets of initial soil moisture conditions; (c) run of hydrological and hydraulic simulation models with random sets of parameter values, picked from suitable distributions; (d) statistical analysis of the model outputs and determination of empirical pdfs; and (e) selection of the design value, which corresponds to the acceptable risk. This approach allows for estimating the full probability distribution of the output variables, instead of a unique value, as resulted by the deterministic procedure. In this context, stochastic simulation also offers the means to introduce the missing culture of uncertainty appreciation in flood engineering.

    Full text: http://www.itia.ntua.gr/en/getfile/1384/1/documents/KosFloodStochSim.pdf (1860 KB)

    See also: http://dx.doi.org/10.13140/RG.2.2.16848.51201

  1. V. Pagana, A. Tegos, P. Dimitriadis, A. Koukouvinos, P. Panagopoulos, and N. Mamassis, Alternative methods in floodplain hydraulic simulation - Experiences and perspectives, European Geosciences Union General Assembly 2013, Geophysical Research Abstracts, Vol. 15, Vienna, EGU2013-10283-2, European Geosciences Union, 2013.

    Floods can simply be defined as the physical phenomena, during which an initially dry land area is covered by water. Floods are normally caused by extreme weather conditions, while their evolution depends mainly on geomorphologic factors, such as soil stability, vegetation cover, as well as the geometrical characteristics of the river basin. To prevent floods’ consequences, we have to study the hydraulic behavior of all the basins. Here, the study is focused on the upstream part of the Rafina basin, located in the east of Athens (Greece). Particularly, a hydraulic simulation is accomplished via the one-dimensional HEC-RAS and the quasi-two-dimensional LISFLOOD-FP and FLO-2D models. Additionally, a sensitivity analysis is carried out to investigate the effects of the floodplain and river roughness coefficients on the flood inundation in conjunction with a modern probabilistic view. Finally, a comparison between the three models is made regarding the simulated maximum water depth and maximum flow velocity.

    Full text:

    Other works that reference this work (this list might be obsolete):

    1. #Μίχας, Σ. Ν., Κ. Ι. Νικολάου, Σ. Λ. Λαζαρίδου, και Μ. Ν. Πικούνης, Σύγκριση μαθηματικών ομοιωμάτων διόδευσης πλημμυρικού κύματος από υποθετική θραύσης φράγματος Αγιόκαμπου, Πρακτικά 2ου Πανελλήνιου Συνεδρίου Φραγμάτων και Ταμιευτήρων, Αθήνα, Αίγλη Ζαππείου, Ελληνική Επιτροπή Μεγάλων Φραγμάτων, 2013.

  1. A. Oikonomou, P. Dimitriadis, A. Koukouvinos, A. Tegos, V. Pagana, P. Panagopoulos, N. Mamassis, and D. Koutsoyiannis, Floodplain mapping via 1D and quasi-2D numerical models in the valley of Thessaly, Greece, European Geosciences Union General Assembly 2013, Geophysical Research Abstracts, Vol. 15, Vienna, EGU2013-10366, doi:10.13140/RG.2.2.25165.03040, European Geosciences Union, 2013.

    The European Union Floods Directive defines a flood as ‘a covering by water of land not normally covered by water’. Human activities, such as agriculture, urban development, industry and tourism, contribute to an increase in the likelihood and adverse impacts of flood events. The study of the hydraulic behaviour of a river is important in flood risk management. Here, we investigate the behaviour of three hydraulic models, with different theoretical frameworks, in a real case scenario. The area is located in the Penios river basin, in the plain of Thessaly (Greece). The three models used are the one-dimensional HEC-RAS and the quasi two-dimensional LISFLOOD-FP and FLO-2D which are compared to each other, in terms of simulated maximum water depth as well as maximum flow velocity, and to a real flood event. Moreover, a sensitivity analysis is performed to determine how each simulation is affected by the river and floodplain roughness coefficient, in terms of flood inundation.

    Full text:

    See also: http://dx.doi.org/10.13140/RG.2.2.25165.03040

    Other works that reference this work (this list might be obsolete):

    1. #Μίχας, Σ. Ν., Κ. Ι. Νικολάου, Σ. Λ. Λαζαρίδου, και Μ. Ν. Πικούνης, Σύγκριση μαθηματικών ομοιωμάτων διόδευσης πλημμυρικού κύματος από υποθετική θραύσης φράγματος Αγιόκαμπου, Πρακτικά 2ου Πανελλήνιου Συνεδρίου Φραγμάτων και Ταμιευτήρων, Αθήνα, Αίγλη Ζαππείου, Ελληνική Επιτροπή Μεγάλων Φραγμάτων, 2013.

  1. A. Varveris, P. Panagopoulos, K. Triantafillou, A. Tegos, A. Efstratiadis, N. Mamassis, and D. Koutsoyiannis, Assessment of environmental flows of Acheloos Delta, European Geosciences Union General Assembly 2010, Geophysical Research Abstracts, Vol. 12, Vienna, 12046, doi:10.13140/RG.2.2.14849.66404, European Geosciences Union, 2010.

    Acheloos, the river with the highest discharge among rivers of Greece, hosts three hydroelectric dams, while two more dams are under construction. In addition, there are plans for partial diversion of the river to a nearby water district, for irrigation and hydroelectric development. The Acheloos Delta is considered to be one of the most significant Mediterranean wetland habitats for its ecological importance, including fish fauna. In this case study we aim to redefine the ecological flow and propose an outflow management policy from the most downstream reservoir (Stratos), in order to preserve the ecosystem at the Acheloos Delta. A hydrological analysis is employed to reconstruct the natural discharge records along the river on a daily basis, accompanied by a detailed evaluation of alternative methodologies for the estimation of the ecological flow. Based on the results of the analyses, the corresponding water management policy is determined, taking into account the characteristics of the hydropower plan and the related hydraulic works.

    Full text:

    See also: http://dx.doi.org/10.13140/RG.2.2.14849.66404

    Other works that reference this work (this list might be obsolete):

    1. #Fourniotis, N. T., M. Stavropoulou-Gatsi and I. K. Kalavrouziotis, Acheloos River: The timeless, and since ancient period, contribution to the development and environmental upgrading of Western Greece, Proceedings 3rd IWA Specialized Conference on Water & Wastewater Technologies in Ancient Civilizations, Istanbul-Turkey, 420-428, 2012.
    2. Fourniotis, N. T., A proposal for impact evaluation of the diversion of the Acheloos River on the Acheloos estuary in Western Greece, International Journal of Engineering Science and Technology, 4(4), 1792-1802, 2012.

  1. A. Tegos, N. Mamassis, and D. Koutsoyiannis, Estimation of potential evapotranspiration with minimal data dependence, European Geosciences Union General Assembly 2009, Geophysical Research Abstracts, Vol. 11, Vienna, 1937, doi:10.13140/RG.2.2.27222.86089, European Geosciences Union, 2009.

    We develop a parametric expression which approximates the Penman-Monteith equation thus providing easy estimation of the potential evapotranspiration with minimal data requirements. Namely, the method requires as inputs the mean temperature and the extraterrestrial radiation, from which only the temperature needs to be measured. The model was applied on a monthly step in 37 meteorological stations of Greece for the periods 1968-1983 (calibration period) and 1984-1989 (validation period). The results are satisfactory as the efficiency is greater than 0.97 for all stations and for both calibration and validation periods. Initially, the parametric expression involves three parameters but regional analysis indicates that reduction to one or two parameters is possible and does not increase the error substantially. Using optimization and geographic interpolation through a geographical information system, the parameter values were mapped for the entire territory of Greece, which makes the method directly applicable to any site in the country, the only requirement being that mean temperature data be available.

    Full text:

    See also: http://dx.doi.org/10.13140/RG.2.2.27222.86089

    Other works that reference this work (this list might be obsolete):

    1. Tabari, H., P. H. Talaee, P. Willems, and C. Martinez, Validation and calibration of solar radiation equations for estimating daily reference evapotranspiration at cool semi-arid and arid locations, Hydrological Sciences Journal, 2014.

  1. A. Efstratiadis, A. Tegos, I. Nalbantis, E. Rozos, A. Koukouvinos, N. Mamassis, S.M. Papalexiou, and D. Koutsoyiannis, Hydrogeios, an integrated model for simulating complex hydrographic networks - A case study to West Thessaly region, 7th Plinius Conference on Mediterranean Storms, Rethymnon, Crete, doi:10.13140/RG.2.2.25781.06881, European Geosciences Union, 2005.

    An integrated scheme, comprising a conjunctive hydrological model and a systems oriented management model, was developed, based on a semi-distributed approach. Geographical input data include the river network, the sub-basins upstream of each river node and the aquifer dicretization in the form of groundwater cells of arbitrary geometry. Additional layers of distributed geographical information, such as geology, land cover and terrain slope, are used to define the hydrological response units. Various modules are combined to represent the main processes at the water basin such as, soil moisture, groundwater, flood routing and water management models. Model outputs include river discharges, spring flows, groundwater levels and water abstractions. The model can be implemented in daily and monthly basis. A case study to the West Thessaly region performed. The discharges of five hydrometric stations and the water levels of eight boreholes were used simultaneously for model calibration. The implementation of the model to the certain region demonstrated satisfactory agreement between the observed and the simulated data.

    Full text:

    See also: http://dx.doi.org/10.13140/RG.2.2.25781.06881

Presentations and publications in workshops

  1. A. Tegos, A. Efstratiadis, A. Varveris, N. Mamassis, A. Koukouvinos, and D. Koutsoyiannis, Assesment and implementation of ecological flow constraints in large hydroelectric works: The case of Acheloos, Ecological flow of rivers and the importance of their true assesment, 2014.

    Full text: http://www.itia.ntua.gr/en/getfile/1455/1/documents/2014_envflows_pres.pdf (1344 KB)

  1. D. Koutsoyiannis, N. Mamassis, and A. Tegos, Hydrometeorological issues in ancient Greek science and philosophy, The Eco-nomy of Water, edited by E Efthymiopoulos and M. Modinos, Hydra island, doi:10.13140/RG.2.2.25574.63040, Hellenica Grammata, 2009.

    Technological applications aiming at the exploitation of the natural sources appear in all ancient civilizations. The unique phenomenon in the ancient Greek civilization is that technological needs triggered physical explanations of natural phenomena, thus enabling the foundation of philosophy and science. Among these, the study of hydrometeorological phenomena had a major role. This study begins with the Ionian philosophers in the seventh century BC, continues in classical Athens in the fifth and fourth centuries BC, and advances and expands through the entire Greek world up to the end of Hellenistic period. Many of the theories developed by ancient Greeks are erroneous according to modern views. However, many elements in Greek exegeses of hydrometeorological processes, such as evaporation and condensation of vapour, creation of clouds, hail, snow and rainfall, and evolution of hydrological cycle, are impressive even today.

    Related works:

    • [7] English text (publication in Water Science and Technology: Water Supply)

    Full text:

    See also: http://dx.doi.org/10.13140/RG.2.2.25574.63040

Various publications

  1. A. Tegos, Acheloos, 2009.

    Full text: http://www.itia.ntua.gr/en/getfile/937/1/documents/acheloos_tegos_2.pdf (271 KB)

  1. A. Tegos, Acheloos: Does the water belong only to fish?, March 2009.

    Full text: http://www.itia.ntua.gr/en/getfile/935/1/documents/axelwos_tegos1.pdf (200 KB)

Academic works

  1. A. Tegos, Simplification of evapotranspiration estimation in Greece, Postgraduate Thesis, Department of Water Resources and Environmental Engineering – National Technical University of Athens, Athens, 2007.

    The scope of the study is the development of a new model, in order to estimate the potential evaportranspiration. The new model is based on the formulation of a parametric equation, that is adapted in a sample calculated at Penman- Monteith data. The adaptation becomes with the method of minimal square and the new model requires the medium temperature and the extraterrestrial radiation, as entry data, which only the temperature needs to be measured. The model was applied in 37 meteorological stations of Greece for the periods 1968-1983 and 1984-1989, in monthly step. The first decade refers to the calibration period, whereas the second one is the validation period, in which the forecasting capacity of the model was tested. Through optimization the initial parameters were reduced, so as to simplify the mathematic equation. The results were particularly satisfactory. Finally, geographic interpolation of parameters was realized, with the use of G.I.S, on the inference of parameters in all the Hellenic space.

    Full text:

    Additional material:

    Other works that reference this work (this list might be obsolete):

    1. Papadavid, G. C., A. Agapiou, S. Michaelides and D. G.Hadjimitsis, The integration of remote sensing and meteorological data for monitoring irrigation demand in Cyprus, Nat. Hazards Earth Syst. Sci., 9, 2009-2014, 2009.
    2. Hadjimitsis, D. G., and G. Papadavid, Integrated approach of remote sensing and micro-sensor technology for estimating evapotranspiration in Cyprus, Agric Eng Int: CIGR Journal 12 (3-4), 1-11, 2010.
    3. Papadavid, G., D. Hadjimitsis, S. Michaelides and A. Nisantzi, Crop evapotranspiration estimation using remote sensing and the existing network of meteorological stations in Cyprus, Adv. Geosci., 30, 39-44, doi: 10.5194/adgeo-30-39-2011, 2011.
    4. #Hadjimitsis, D. G. and G. Papadavid, Remote Sensing for Determining Evapotranspiration and Irrigation Demand for Annual Crops, Remote Sensing of Environment - Integrated Approaches, 10.5772/39305, 2013.

  1. A. Tegos, Combined simultation of hydrological-hydrogeological processes and operation of Western Thessaly hydrosystem, Diploma thesis, 132 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, September 2005.

    The scope of the study is the integrated simulation of the hydrological cycle in the Western Thessaly region, through the HYDROGEIOS model. First, the raw data for the hydrosystem was collected (data from hydrometric and pluviometric stations, groundwater data, agricultural data). Next, we proceeded to the schematisation of the physical and artificial system. For the adaptation of the model, i.e. the estimation of its parameters, an objective function was formulated, based on field measurements for surface and groundwater resources. The function comprises 16 components. Through optimisation, we attemted to find the minimum distance between the observed and simulated time series. The study refers to the period 1972-73 to 1992-93. The first decade refers to the calibration period, whereas the second one is the validation period, in which the forecasting capacity of the model was tested. Taking into account thecomplexity of the problem, the adaptation of the model was satisfactory, while useful conclusions were derived, which may be used for management purposes.

    Full text: http://www.itia.ntua.gr/en/getfile/679/1/documents/2005tegos.pdf (8166 KB)

    Additional material:

Research reports

  1. A. Koukouvinos, A. Efstratiadis, D. Nikolopoulos, H. Tyralis, A. Tegos, N. Mamassis, and D. Koutsoyiannis, Case study in the Acheloos-Thessaly system, Combined REnewable Systems for Sustainable ENergy DevelOpment (CRESSENDO), 98 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, October 2015.

    This report describes the validation of methodologies and computer tools that have been developed in the context of the research project, in the interconnected river basin system of Acheloos and Peneios. The study area is modelled as a hypothetically closed and autonomous (in terms of energy balance) system, in order to investigate the perspectives of sustainable development at the peripheral scale, merely based on renewable energy.

    Related project: Combined REnewable Systems for Sustainable ENergy DevelOpment (CRESSENDO)

    Full text: http://www.itia.ntua.gr/en/getfile/1613/1/documents/Report_EE4a.pdf (8010 KB)

  1. N. Mamassis, R. Mavrodimou, A. Efstratiadis, M. Heidarlis, A. Tegos, A. Koukouvinos, P. Lazaridou, M. Magaliou, and D. Koutsoyiannis, Investigation of alternative organisations and operations of a Water Management Body for the Smokovo projects, Investigation of management scenarios for the Smokovo reservoir, Report 2, 73 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, March 2007.

    The framework regarding the establishment and operation of a water management body for the Smokovo reservoir and the related projects is investigated. The study area, as well as the responsibility area within it, is defined, and a short description of the characteristics for the physical and artificial system is made. The current legal and institutional framework is examined, on the basis of which various alternative schemes are proposed for the management body. Its legal and administrative status, the competence and the organogram are specified, and an initial financial analysis is attempted, to validate its viability. Finally, the next actions are proposed, regarding the organization of deliberations with the related organs.

    Related project: Investigation of management scenarios for the Smokovo reservoir

    Full text: http://www.itia.ntua.gr/en/getfile/720/1/documents/Smo_teyx2ekd3.pdf (2847 KB)

    Additional material:

  1. A. Efstratiadis, A. Tegos, G. Karavokiros, I. Kyriazopoulou, and I. Vazimas, Master Plan for water resources management for the area of Karditsa, Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS), Report 16, 132 pages, NAMA, Athens, December 2006.

    The present report refers to the Master Plan for water resources management for the area of Karditsa and was elaborated by NAMA's research team in cooperation with DEYA Karditsa and the National Technical University of Athens. This deliverable is part of Work Package 8 with title "Pilot Applications". The Pilot Applications aim to test and evaluate the product (from methodology and software efficiency viewpoints) on hydrosystems with totally different characteristics, in terms of their hydroclimatic regime, structure scale, and institutional and administrative framework of management. After the completion of the pilot applications, the product was re-examined at all levels (theoretical background, software design and implementation), before assuming its final form. This report will include the following main sections, according to the Technical Addendum of the Contract: (a) description of the study area, (b) description of the hydrosystem, (c) data and processing, (d) water needs assessment, (e) hydrological inflow assessment, (f) management of the hydrosystem, (g) simulation of quality parameters, (h) financial analysis and (i) conclusions and proposals.

    Related project: Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS)

    Full text: http://www.itia.ntua.gr/en/getfile/769/1/documents/report_16.pdf (5557 KB)

    Additional material:

    Other works that reference this work (this list might be obsolete):

    1. #Strosser P., J. Roussard, B. Grandmougin, M. Kossida, I. Kyriazopoulou, J. Berbel, S. Kolberg, J. A. Rodríguez-Díaz, P. Montesinos, J. Joyce, T. Dworak, M. Berglund, and C. Laaser, EU Water saving potential (Part 2 – Case Studies), Berlin, Allemagne, Ecologic – Institute for International and European Environmental Policy, 101 pp., 2007.

  1. A. Efstratiadis, A. Koukouvinos, E. Rozos, A. Tegos, and I. Nalbantis, Theoretical documentation of model for simulating hydrological-hydrogeological processes of river basin "Hydrogeios", Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS), Contractor: NAMA, Report 4a, 103 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, December 2006.

    The subject of the report is the development of the software system HYDROGEIOS, which represents the hydrological and hydrogeological processes as well as the water resource management practices of a river basin. After a short review of the most recognized hydrological models and a general overview of the problem, we describe the theoretical background of the approach, comprising the combined operation of three models: (a) a conceptual soil moisture accounting model, with different parameters for each hydrological response unit, which estimates the transformation of precipitation to evapotranspiration, surface runoff and percolation; (b) a multicell groundwater model, which estimates the spatial distribution of the water table, the baseflow (spring runoff) and the underground losses; and (c) a water resources allocation model, which for given hydrological inflows along the river network, given characteristics of technical facilities (aqueducts, wells) and given targets and constraints, estimates the abstractions and the water balance at all hydrosystem control points, selecting the economical optimal management. The spatial analysis assumes a semi-distributed schematisation of the basin and its underlying aquifer, and also a rough description of the technical works, all employed via the use of geographical information systems. The time step of simulation is monthly or daily; in the last case, a routing model is optionally incorporated, based on the well-known Muskingum-Cunge method. Specific emphasis is given to the estimation of model parameters, by using statistical and empirical goodness-of-fit measures and evolutionary algorithms for single- and multi-objective optimisation. Finally, we present an application of the model to the Western Thessaly area.

    Related project: Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS)

    Full text: http://www.itia.ntua.gr/en/getfile/755/1/documents/report_4a.pdf (3877 KB)