Nikos Malamos


nmalamos@hydro.ntua.gr
+30 210 772 2325
http://www.itia.ntua.gr/~nmalamos

Participation in research projects

Participation as Researcher

  1. Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS)

Published work

Publications in scientific journals

  1. N. Malamos, A. Tegos, G. Bourantas, C. Chalvantzis, and D. Koutsoyiannis, Global reference evapotranspiration clustering and its relation to the Köppen-Geiger climate classification, Journal of Hydrology, 2025, (in review).
  2. G.-F. Sargentis, R. Ioannidis, P. Dimitriadis, N. Malamos, O. Lyra, O. Kitsou, M. Kougia, N. Mamassis, and D. Koutsoyiannis, Energy Self-Sufficiency in Rural Areas; Case Study: North Euboea, Greece, Advances in Environmental and Engineering Research, 5 (4), 20 pages, doi:10.21926/aeer.2404025, 2024.
  3. T. Iliopoulou, D. Koutsoyiannis, N. Malamos, A. Koukouvinos, P. Dimitriadis, N. Mamassis, N. Tepetidis, and D. Markantonis, A stochastic framework for rainfall intensity–time scale–return period relationships. Part ΙΙ: point modelling and regionalization over Greece, Hydrological Sciences Journal, 69 (8), 1092–1112, doi:10.1080/02626667.2024.2345814, 2024.
  4. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, and N. Malamos, A stochastic framework for rainfall intensity–time scale–return period relationships. Part I: theory and estimation strategies, Hydrological Sciences Journal, 69 (8), 1082–1091, doi:10.1080/02626667.2024.2345813, 2024.
  5. N. Malamos, D. Koulouris, I. L. Tsirogiannis, and D. Koutsoyiannis, Evaluation of BOLAM fine grid weather forecasts with emphasis on hydrological applications, Hydrology, 10 (8), 162, doi:10.3390/hydrology10080162, 2023.
  6. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, In search of climate crisis in Greece using hydrological data: 404 Not Found, Water, 15 (9), 1711, doi:10.3390/w15091711, 2023.
  7. T. Iliopoulou, N. Malamos, and D. Koutsoyiannis, Regional ombrian curves: Design rainfall estimation for a spatially diverse rainfall regime, Hydrology, 9 (5), 67, doi:10.3390/hydrology9050067, 2022.
  8. A. Tegos, N. Malamos, and D. Koutsoyiannis, RASPOTION - A new global PET dataset by means of remote monthly temperature data and parametric modelling, Hydrology, 9 (2), 32, doi:10.3390/hydrology9020032, 2022.
  9. N. Mamassis, K. Mazi, E. Dimitriou, D. Kalogeras, N. Malamos, S. Lykoudis, A. Koukouvinos, I. L. Tsirogiannis, I. Papageorgaki, A. Papadopoulos, Y. Panagopoulos, D. Koutsoyiannis, A. Christofides, A. Efstratiadis, G. Vitantzakis, N. Kappos, D. Katsanos, B. Psiloglou, E. Rozos, T. Kopania, I. Koletsis, and A. D. Koussis, OpenHi.net: A synergistically built, national-scale infrastructure for monitoring the surface waters of Greece, Water, 13 (19), 2779, doi:10.3390/w13192779, 2021.
  10. N. Malamos, and D. Koutsoyiannis, Field survey and modelling of irrigation water quality indices in a Mediterranean island catchment: A comparison between spatial interpolation methods, Hydrological Sciences Journal, 63 (10), 1447–1467, doi:10.1080/02626667.2018.1508874, 2018.
  11. N. Malamos, I. L. Tsirogiannis, A. Tegos, A. Efstratiadis, and D. Koutsoyiannis, Spatial interpolation of potential evapotranspiration for precision irrigation purposes, European Water, 59, 303–309, 2017.
  12. A. Tegos, N. Malamos, A. Efstratiadis, I. Tsoukalas, A. Karanasios, and D. Koutsoyiannis, Parametric modelling of potential evapotranspiration: a global survey, Water, 9 (10), 795, doi:10.3390/w9100795, 2017.
  13. N. Malamos, and D. Koutsoyiannis, Bilinear surface smoothing for spatial interpolation with optional incorporation of an explanatory variable. Part 2: Application to synthesized and rainfall data, Hydrological Sciences Journal, 61 (3), 527–540, doi:10.1080/02626667.2015.1080826, 2016.
  14. N. Malamos, and D. Koutsoyiannis, Bilinear surface smoothing for spatial interpolation with optional incorporation of an explanatory variable. Part 1:Theory, Hydrological Sciences Journal, 61 (3), 519–526, doi:10.1080/02626667.2015.1051980, 2016.
  15. 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.
  16. 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.
  17. N. Malamos, and D. Koutsoyiannis, Broken line smoothing for data series interpolation by incorporating an explanatory variable with denser observations: Application to soil-water and rainfall data, Hydrological Sciences Journal, doi:10.1080/02626667.2014.899703, 2015.

Book chapters and fully evaluated conference publications

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, Extreme rainfall modelling for the design of hydraulic works and dams: the new methodology and its application in Greece [Invited talk], Proceedings of 4th Hellenic Conference on Dams and Reservoirs, War Museum Athens, doi:10.13140/RG.2.2.24009.35689, Hellenic Commission on Large Dams, Athens, 2024.
  2. 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 "Panta Rhei", Athens, European Water Resources Association, 2017.

Conference publications and presentations with evaluation of abstract

  1. T. Iliopoulou, D. Koutsoyiannis, N. Malamos, A. Koukouvinos, P. Dimitriadis, N. Mamassis, N. Tepetidis, and D. Markantonis, A stochastic framework for rainfall intensity-timescale-return period relationships regionalized over Greece, European Geosciences Union General Assembly 2024, Vienna, Austria & Online, EGU24-9043, doi:10.5194/egusphere-egu24-9043, 2024.
  2. T. Iliopoulou, D. Koutsoyiannis, A. Koukouvinos, N. Malamos, N Tepetidis, D. Markantonis, P. Dimitriadis, and N. Mamassis, Regionalized design rainfall curves for Greece, European Geosciences Union General Assembly 2023, Vienna, Austria & Online, EGU23-8740, doi:10.5194/egusphere-egu23-8740, 2023.
  3. A. Efstratiadis, N. Mamassis, A. Koukouvinos, D. Koutsoyiannis, K. Mazi, A. D. Koussis, S. Lykoudis, E. Demetriou, N. Malamos, A. Christofides, and D. Kalogeras, Open Hydrosystem Information Network: Greece’s new research infrastructure for water, European Geosciences Union General Assembly 2020, Geophysical Research Abstracts, Vol. 22, Vienna, EGU2020-4164, doi:10.5194/egusphere-egu2020-4164, 2020.
  4. 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.
  5. 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.

Presentations and publications in workshops

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, Extreme rainfall modelling for engineering design: a new methodology and its application over the Greek territory (invited), Risk Management: Extremes of Flood and Drought, Europe/China, UNESCO, 2023.
  2. I. L. Tsirogiannis, N. Malamos, P. Barouchas, P. Baltzoi, K. Fotia, G. Tenedios, D. Giotis, D. Kateris, E. Tsoumani, S. Chiras, and A. Christofides, Evaluation of the application of the IRMA_SYS irrigation DSS on kiwi crop, 28th Conference of the Hellenic Horticulture Science Company, Thessaloniki, 465–468, October 2017.

Academic works

  1. N. Malamos, Methodology development for spatial interpolation of hydrometeorological variables using broken line smoothing techniques, Postgraduate Thesis, 124 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, 2000.

Research reports

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, Technical Report, Production of maps with updated parameters of the ombrian curves at country level (impementation of the EU Directive 2007/60/EC in Greece), Department of Water Resources and Environmental Engineering – National Technical University of Athens, 2023.
  2. N. Malamos, and I. Nalbantis, Analysis of the water demand management practices, Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS), Contractor: NAMA, Report 15, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, June 2005.

Details on research projects

Participation as Researcher

  1. Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS)

    Duration: July 2003–June 2006

    Budget: €779 656

    Commissioned by: General Secretariat of Research and Technology

    Contractor: NAMA

    Collaborators:

    1. Department of Water Resources, Hydraulic and Maritime Engineering
    2. Municipal Company of Water Supply and Sewerage of Karditsa
    3. Aeiforiki Dodekanisou
    4. Marathon Data Systems

    Project director: D. Koutsoyiannis

    Principal investigator: A. Andreadakis

    Programme: ΕΠΑΝ, Φυσικό Περιβάλλον και Βιώσιμη Ανάπτυξη

    The project aims at providing support to decision-making processes within the direction of integrated management of water resource systems at a variety of scales. Several methodologies and computing tools are developed, which are incorporated into an integrated information system. The main deliverable is an operational software package of general use, which is evaluated and tested on two pilot case studies, concerning hydrosystems in Greece with varying characteristics (Karditsa, Dodecanesus). The end-product of the project is a software system for simulation and optimisation of hydrosystem operation, as well as a series of separate software applications for solving specific problems, aiming at producing input data to the central system or post-processing of the results. The project includes eleven work packages, eight for basic research, two for industrial research and one for the pilot applications.

Published work in detail

Publications in scientific journals

  1. N. Malamos, A. Tegos, G. Bourantas, C. Chalvantzis, and D. Koutsoyiannis, Global reference evapotranspiration clustering and its relation to the Köppen-Geiger climate classification, Journal of Hydrology, 2025, (in review).

    This study introduces a global clustering approach for reference evapotranspiration (ET₀) based on spectral clustering techniques. By analyzing 3139 stations worldwide, the method segments the globe into 45 unique clusters that reflect shared ET₀ dynamics. This clustering technique not only enhances the accuracy of ET₀ estimation but also provides a simplified method for computing ET₀ in areas where meteorological data are limited. The spatial extent of these clusters allows for the application of pre-calculated parameters, streamlining ET₀ calculation and reducing the computational complexity typically involved. This approach draws an analogy to the Köppen-Geiger climate classification, aligning ET₀ clusters with well-established climate zones, thus revealing patterns between evapotranspiration and global climate behavior. Moreover, the study demonstrates that the clusters can be utilized to calibrate other ET₀ estimation methods, offering a tool for guiding regional model adjustments. The validation of this method, using 30 stations from diverse climates, showed strong correlations and acceptable performance metrics, indicating its applicability for hydrological and engineering tasks. In conclusion, this global ET₀ clustering provides a robust, accessible framework for water resource management, irrigation planning, and climate adaptation strategies, particularly in data-scarce regions.

    Additional material:

  1. G.-F. Sargentis, R. Ioannidis, P. Dimitriadis, N. Malamos, O. Lyra, O. Kitsou, M. Kougia, N. Mamassis, and D. Koutsoyiannis, Energy Self-Sufficiency in Rural Areas; Case Study: North Euboea, Greece, Advances in Environmental and Engineering Research, 5 (4), 20 pages, doi:10.21926/aeer.2404025, 2024.

    The modern globalized civilization is sustained by interactions, trade, the transportation of goods, and energy. Energy self-sufficiency is crucial in rural and disaster-prone areas like North Euboea because dependence on external energy supplies can leave regions vulnerable to supply chain disruptions, price volatility, and geopolitical risks. In such isolated regions, energy independence ensures resilience in natural disasters and economic instability. The alternative to self-sufficiency often involves reliance on centralized energy systems, fossil fuels, or external imports, which may not always be reliable or sustainable. Therefore, in this study, we explore the possibility of an area having energy self-sufficiency. As a case study, we chose North Euboea in Greece, explicitly focusing on the Municipality of Mantoudi-Limni-Agia Anna. The analysis combines local land use patterns, energy needs for inhabitants, agriculture and water requirements. It is followed by exploring various renewable energy sources, including hydropower, biomass, solar, and wind. We considered the stochastic nature of renewable energy production and the challenges associated with energy storage. The findings suggest that while wind turbines and solar panels could be installed in the area and contribute significantly to energy needs, achieving complete self-sufficiency requires careful planning, particularly regarding energy storage and the social acceptance of these installations. The results highlight the need for a holistic approach that integrates environmental, landscape, societal, and technical considerations in designing and implementing renewable energy systems. Additionally, it is highlighted that the available renewable energy from forest biomass (before the 2021 megafire event) could reliably and adequately meet the area's energy needs without requiring investments in photovoltaic parks and wind turbines and without competing with the use of agricultural land.

    Full text: http://www.itia.ntua.gr/en/getfile/2514/1/documents/aeer.2404025.pdf (2020 KB)

  1. T. Iliopoulou, D. Koutsoyiannis, N. Malamos, A. Koukouvinos, P. Dimitriadis, N. Mamassis, N. Tepetidis, and D. Markantonis, A stochastic framework for rainfall intensity–time scale–return period relationships. Part ΙΙ: point modelling and regionalization over Greece, Hydrological Sciences Journal, 69 (8), 1092–1112, doi:10.1080/02626667.2024.2345814, 2024.

    In this work, we formulate a regionalization framework for rainfall intensity–time scale–return period relationships which is applied over the Greek territory. The methodology for single-site estimation is based on a stochastic framework for multi-scale modelling of rainfall intensity which is outlined in the companion paper. Five parameters are first fitted independently for each site and the resulting parameter variability is assessed. Following a systematic investigation of uncertainty and variability patterns, two parameters, i.e. the tail-index and a time scale parameter, are identified as constant in space and estimated using data pooling techniques. The other three parameters are regionalized over Greece by means of spatial interpolation and smoothing techniques that are assessed through cross-validation in a multi-model framework. The regionalization scheme is implemented in a sequential order that allows exploiting rainfall information both from rainfall stations with sub-daily resolution and from the more reliable network of daily raingauges.

    Additional material:

    See also: https://www.tandfonline.com/eprint/4TB9ZKAU4ARWKADERNXD/full?target=10.1080/02626667.2024.2345814

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, and N. Malamos, A stochastic framework for rainfall intensity–time scale–return period relationships. Part I: theory and estimation strategies, Hydrological Sciences Journal, 69 (8), 1082–1091, doi:10.1080/02626667.2024.2345813, 2024.

    This work presents a stochastic framework for the construction of rainfall intensity–time scale–return period relationships, which was applied in the recent regionalization of design rainfall curves over the Greek territory, described in a companion paper. The methodology outlined herein builds upon a widely-used mathematical framework, which has been recently revisited and upgraded, and incorporates two different versions: (a) a theoretically consistent stochastic model applicable for rainfall intensity over any scale of interest; and (b) a simplified version valid over small scales, which makes parameter estimation easier. Special attention is given to the presentation of the simplified version, which suffices for most engineering tasks. Parameter estimation approaches are presented in detail, including the K-moments framework that allows for reliable high-order moment estimation and handling of bias due to spatiotemporal dependence.

    Additional material:

    See also: https://www.tandfonline.com/eprint/7GZTUDAI6IGZZANREA6T/full?target=10.1080/02626667.2024.2345813

  1. N. Malamos, D. Koulouris, I. L. Tsirogiannis, and D. Koutsoyiannis, Evaluation of BOLAM fine grid weather forecasts with emphasis on hydrological applications, Hydrology, 10 (8), 162, doi:10.3390/hydrology10080162, 2023.

    The evaluation of weather forecast accuracy is of major interest in decision making in almost every sector of the economy and in civil protection. To this, a detailed assessment of Bologna Limited-Area Model (BOLAM) seven days fine grid 3 h predictions is made for precipitation, air temperature, relative humidity, and wind speed over a large lowland agricultural area of a Mediterranean-type climate, characterized by hot summers and rainy moderate winters (plain of Arta, NW Greece). Timeseries that cover a four-year period (2016–2019) from seven agro-meteorological stations located at the study area are used to run a range of contingency and accuracy measures as well as Taylor diagrams, and the results are thoroughly discussed. The overall results showed that the model failed to comply with the precipitation regime throughout the study area, while the results were mediocre for wind speed. Considering relative humidity, the results revealed acceptable performance and good correlation between the model output and the observed values, for the early days of forecast. Only in air temperature, the forecasts exhibited very good performance. Discussion is made on the ability of the model to predict major rainfall events and to estimate water budget components as rainfall and reference evapotranspiration. The need for skilled weather forecasts from improved versions of the examined model that may incorporate post-processing techniques to improve predictions or from other forecasting services is underlined.

    Full text: http://www.itia.ntua.gr/en/getfile/2333/1/documents/hydrology-10-00162-v2pdf.pdf (8599 KB)

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, In search of climate crisis in Greece using hydrological data: 404 Not Found, Water, 15 (9), 1711, doi:10.3390/w15091711, 2023.

    In the context of implementing the European Flood Directive in Greece, a large set of rainfall data was compiled with the principal aim of constructing rainfall intensity–timescale–return period relationships for the entire country. This set included ground rainfall data as well as non-conventional data from reanalyses and satellites. Given the European declaration of climate emergency, along with the establishment of a ministry of climate crisis in Greece, this dataset was also investigated from a climatic perspective using the longest of the data records to assess whether or not they support the climate crisis doctrine. Monte Carlo simulations, along with stationary Hurst–Kolmogorov (HK) stochastic dynamics, were also employed to compare data with theoretical expectations. Rainfall extremes are proven to conform with the statistical expectations under stationarity. The only notable climatic events found are the clustering (reflecting HK dynamics) of water abundance in the 1960s and dry years around 1990, followed by a recovery from drought conditions in recent years.

    https://www.itia.ntua.gr/en/getfile/2287/3/documents/GraphicalAbstract404.jpg

    Full text: http://www.itia.ntua.gr/en/getfile/2287/1/documents/water-15-01711-v2.pdf (7639 KB)

    Additional material:

  1. T. Iliopoulou, N. Malamos, and D. Koutsoyiannis, Regional ombrian curves: Design rainfall estimation for a spatially diverse rainfall regime, Hydrology, 9 (5), 67, doi:10.3390/hydrology9050067, 2022.

    Ombrian curves, i.e., curves linking rainfall intensity to return period and time scale, are well-established engineering tools crucial to the design against stormwaters and floods. Though the at-site construction of such curves is considered a standard hydrological task, it is a rather challenging one when large regions are of interest. Regional modeling of ombrian curves is particularly complex due to the need to account for spatial dependence together with the increased variability of rainfall extremes in space. We develop a framework for the parsimonious modeling of the extreme rainfall properties at any point in a given area. This is achieved by assuming a common ombrian model structure, except for a spatially varying scale parameter which is itself modeled by a spatial smoothing model for the 24 h average annual rainfall maxima that employs elevation as an additional explanatory variable. The fitting is performed on the pooled all-stations data using an advanced estimation procedure (K-moments) that allows both for reliable high-order moment estimation and simultaneous handling of space-dependence bias. The methodology is applied in the Thessaly region, a 13 700 km² water district of Greece characterized by varying topography and hydrometeorological properties.

    Full text: http://www.itia.ntua.gr/en/getfile/2188/1/documents/hydrology-09-00067-v3.pdf (9357 KB)

    Additional material:

  1. A. Tegos, N. Malamos, and D. Koutsoyiannis, RASPOTION - A new global PET dataset by means of remote monthly temperature data and parametric modelling, Hydrology, 9 (2), 32, doi:10.3390/hydrology9020032, 2022.

    Regional estimations of Potential Evapotranspiration (PET) are of key interest for a number of geosciences, particularly those that are water-related (hydrology, agrometeorology). Therefore, several models have been developed for the consistent quantification of different time scales (hourly, daily, monthly, annual). During the last few decades, remote sensing techniques have continued to grow rapidly with the simultaneous development of new local and regional evapotranspiration datasets. Here, we develop a novel set T maps over the globe, namely RASPOTION, for the period 2003 to 2016, by integrating: (a) mean climatic data at 4088 stations, extracted by the FAO-CLIMWAT database; (b) mean monthly PET estimates by the Penman–Monteith method, at the aforementioned locations; (c) mean monthly PET estimates by a recently proposed parametric model, calibrated against local Penman–Monteith data; (d) spatially interpolated parameters of the Parametric PET model over the globe, using the Inverse Distance Weighting technique; and (e) remote sensing mean monthly air temperature data. The RASPOTION dataset was validated with in situ samples (USA, Germany, Spain, Ireland, Greece, Australia, China) and by using a spatial Penman–Monteith estimates in England. The results in both cases are satisfactory. The main objective is to demonstrate the practical usefulness of these PET map products across different research disciplines and spatiotemporal scales, towards assisting decision making for both short- and long-term hydro-climatic policy actions.

    Remarks:

    The data accompanying the paper are open and available for free: https://ntuagr-my.sharepoint.com/:f:/g/personal/dkoutsog_ntua_gr/EvSuyFR7zl1Jiax1YKbPhW0BT9-swkLHdw-LuhGE4gd5Cg?e=OtYQMn

    Full text: http://www.itia.ntua.gr/en/getfile/2167/1/documents/hydrology-09-00032-v2.pdf (4154 KB)

  1. N. Mamassis, K. Mazi, E. Dimitriou, D. Kalogeras, N. Malamos, S. Lykoudis, A. Koukouvinos, I. L. Tsirogiannis, I. Papageorgaki, A. Papadopoulos, Y. Panagopoulos, D. Koutsoyiannis, A. Christofides, A. Efstratiadis, G. Vitantzakis, N. Kappos, D. Katsanos, B. Psiloglou, E. Rozos, T. Kopania, I. Koletsis, and A. D. Koussis, OpenHi.net: A synergistically built, national-scale infrastructure for monitoring the surface waters of Greece, Water, 13 (19), 2779, doi:10.3390/w13192779, 2021.

    The large-scale surface-water monitoring infrastructure for Greece Open Hydrosystem Information Network (Openhi.net) is presented in this paper. Openhi.net provides free access to water data, incorporating existing networks that manage their own databases. In its pilot phase, Openhi.net operates three telemetric networks for monitoring the quantity and the quality of surface waters, as well as meteorological and soil variables. Aspiring members must also offer their data for public access. A web-platform was developed for on-line visualization, processing and managing telemetric data. A notification system was also designed and implemented for inspecting the current values of variables. The platform is built upon the web 2.0 technology that exploits the ever-increasing capabilities of browsers to handle dynamic data as a time series. A GIS component offers web-services relevant to geo-information for water bodies. Accessing, querying and downloading geographical data for watercourses (segment length, slope, name, stream order) and for water basins (area, mean elevation, mean slope, basin order, slope, mean CN-curve number) are provided by Web Map Services and Web Feature Services. A new method for estimating the streamflow from measurements of the surface velocity has been advanced as well to reduce hardware expenditures, a low-cost ‘prototype’ hydro-telemetry system (at about half the cost of a comparable commercial system) was designed, constructed and installed at six monitoring stations of Openhi.net.

    Full text: http://www.itia.ntua.gr/en/getfile/2147/1/documents/water-13-02779-v2.pdf (3567 KB)

    See also: https://www.mdpi.com/2073-4441/13/19/2779

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

    1. Spyrou, C., M. Loupis, N. Charizopoulos, P. Arvanitis, A. Mentzafou, E. Dimitriou, S. E. Debele, J. Sahani, and P. Kumar, Evaluating nature-based solution for flood reduction in Spercheios river basin Part 2: Early experimental evidence, Sustainability, 14(6), 10345, doi:10.3390/su141610345, 2022.
    2. #Chrysanthopoulos, E., C. Pouliaris, I. Tsiroggianis, K. Markantonis, P. Kofakis, and A. Kallioras, Evaluating the efficiency of numerical and data driven modeling in forecasting soil water content, Proceedings of the 3rd IAHR Young Professionals Congress, 64-65, 2022.
    3. #Samih, I., and D. Loudyi, Short-term urban water demand forecasting using Theta Models in Casablanca city, Morocco, Proceedings of the 3rd IAHR Young Professionals Congress, International Association for Hydro-Environment Engineering and Research, 2022.
    4. Mazi, K., A. D. Koussis, S. Lykoudis, B. E. Psiloglou, G. Vitantzakis, N. Kappos, D. Katsanos, E. Rozos, I. Koletsis, and T. Kopania, Establishing and operating (pilot phase) a telemetric streamflow monitoring network in Greece, Hydrology, 10(1), 19, doi:10.3390/hydrology10010019, 2023.
    5. Koltsida, E., N. Mamassis, and A. Kallioras, Hydrological modeling using the Soil and Water Assessment Tool in urban and peri-urban environments: the case of Kifisos experimental subbasin (Athens, Greece), Hydrology and Earth System Sciences, 27, 917-931, doi:10.5194/hess-27-917-2023, 2023.
    6. Tsirogiannis, I. L., N. Malamos, and P. Baltzoi, Application of a generic participatory decision support system for irrigation management for the case of a wine grapevine at Epirus, Northwest Greece, Horticulturae, 9(2), 267, doi:10.3390/horticulturae9020267, 2023.
    7. Yeşilköy, S., Ö. Baydaroğlu, N. Singh, Y. Sermet, and I. Demir, A contemporary systematic review of cyberinfrastructure systems and applications for flood and drought data analytics and communication, EarthArXiv, doi:10.31223/X5937W, 2023.
    8. Fotia, K., and I. Tsirogiannis, Water footprint score: A practical method for wider communication and assessment of water footprint performance, Environmental Sciences Proceedings, 25(1), 71, doi:10.3390/ECWS-7-14311, 2023.
    9. Bloutsos, A. A., V. I. Syngouna, I. D. Manariotis, and P. C. Yannopoulos, Seasonal and long-term water quality of Alfeios River Basin in Greece, Water, Air and Soil Pollution, 235, 215, doi:10.1007/s11270-024-06981-1, 2024.
    10. Kalantzopoulos, G., P. Paraskevopoulos, G. Domalis, A. Liopa-Tsakalidi, D. E. Tsesmelis, and P. E. Barouchas, The Western Greece Soil Information System (WΕSIS)—A soil health design supported by the internet of things, soil databases, and artificial intelligence technologies in Western Greece, Sustainability, 16(8), 3478, doi:10.3390/su16083478, 2024.
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  1. N. Malamos, and D. Koutsoyiannis, Field survey and modelling of irrigation water quality indices in a Mediterranean island catchment: A comparison between spatial interpolation methods, Hydrological Sciences Journal, 63 (10), 1447–1467, doi:10.1080/02626667.2018.1508874, 2018.

    A biannual survey of physico-chemical quality indices of 104 irrigation-water wells located in a cultivated plain of a Mediterranean island catchment was conducted using a multi-parameter probe. The campaign was planned so as to differentiate between the dry and wet seasons. The acquired data constituted the test bed for evaluating the results and the features of four spatial interpolation methods, i.e. ordinary kriging, universal kriging, inverse distance weighted and nearest neighbours, against those of the recently introduced bilinear surface smoothing (BSS). In several cases, BSS outperformed the other interpolation methods, especially during the two-fold cross-validation procedure. The study emphasizes the fact that both in situ measurements and good mathematical techniques for studying the spatial distribution of water quality indices are pivotal to agricultural practice management. In the specific case studied, the spatio-temporal variability of water quality parameters and the need for monitoring were evident, as low irrigation water quality was encountered throughout the study area.

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  1. N. Malamos, I. L. Tsirogiannis, A. Tegos, A. Efstratiadis, and D. Koutsoyiannis, Spatial interpolation of potential evapotranspiration for precision irrigation purposes, European Water, 59, 303–309, 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.

    Full text: http://www.itia.ntua.gr/en/getfile/1776/1/documents/EW_2017_59_41_2HOxTxv.pdf (4259 KB)

    See also: http://ewra.net/ew/pdf/EW_2017_59_41.pdf

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

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    8. Kaplan, C. H., M. Büyükyıldız, and C. Köyceğiz, Comparison of interpolation methods in the spatial distribution of monthly precipitation data in Konya closed basin, Konya Journal of Engineering Sciences, 12(4), 920-940, doi:10.36306/konjes.1537038, 2024.

  1. A. Tegos, N. Malamos, A. Efstratiadis, I. Tsoukalas, A. Karanasios, and D. Koutsoyiannis, Parametric modelling of potential evapotranspiration: a global survey, Water, 9 (10), 795, doi:10.3390/w9100795, 2017.

    We present and validate a global parametric model of potential evapotranspiration (PET) with two parameters which are estimated through calibration, using as explanatory variables temperature and extraterrestrial radiation. The model and the parameters estimation approach were tested over the globe, using the FAO CLIMWAT database that provides monthly averaged values of meteorological inputs at 4300 locations worldwide. A preliminary analysis of these data allowed explaining the major drivers of PET over the globe and across seasons. Next, we developed an automatic optimization software tool to calibrate the model and provide point PET estimations against the given Penman-Monteith values. We also employed extended analysis of model inputs and outputs, including the production of global maps of optimized model parameters and associated performance metrics. Also, we employed interpolated values of the optimized parameters to validate the predictive capacity of our model against monthly meteorological time series, at several stations worldwide. The results were very encouraging, since even with the use of abstract climatic information for model calibration and the use of interpolated parameters as local predictors, the model generally ensures reliable PET estimations. In few cases the model performs poorly in estimating the reference PET, due to irregular interactions between temperature and extraterrestrial radiation, as well as because the associated processes are influenced by additional drivers, e.g. relative humidity and wind speed. However, the analysis of the residuals showed that the model is consistent in terms of parameters estimation and model validation. The provided parameters maps allow the direct use of the parametric model wherever in the world, providing PET estimates in case of missing data, that can be further improved even with a short term acquisition of meteorological data.

    Full text: http://www.itia.ntua.gr/en/getfile/1738/2/documents/water-09-00795.pdf (6428 KB)

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    See also: http://www.mdpi.com/2073-4441/9/10/795

    Works that cite this document: View on Google Scholar or ResearchGate

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

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    6. Giménez, P. O., and S. G. García-Galiano, Assessing Regional Climate Models (RCMs) ensemble-driven reference evapotranspiration over Spain, Water, 10(9), 1181, doi:10.3390/w10091181, 2018.
    7. Storm, M. E., R. Gouws, and L. J. Grobler, Novel measurement and verification of irrigation pumping energy conservation under incentive-based programmes, Journal of Energy in Southern Africa, 29(3), 10–21, doi:10.17159/2413-3051/2018/v29i3a3058, 2018.
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    12. Hua, D., X. Hao, Y. Zhang, and J. Qin, Uncertainty assessment of potential evapotranspiration in arid areas, as estimated by the Penman-Monteith method, Journal of Arid Land, 12, 166–180, doi:10.1007/s40333-020-0093-7, 2020.
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    14. Kim, C.-G., J. Lee, J. E. Lee, and H. Kim, Evaluation of improvement effect on the spatial-temporal correction of several reference evapotranspiration methods, Journal of Korea Water Resources Association, 53(9), 701-715, doi:10.3741/JKWRA.2020.53.9.701, 2020.
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    17. Gentilucci, M., M. Bufalini, M. Materazzi, M. Barbieri, D. Aringoli, P. Farabollini, and G. Pambianchi, Calculation of potential evapotranspiration and calibration of the Hargreaves equation using geostatistical methods over the last 10 years in Central Italy, Geosciences, 11(8), 348, doi:10.3390/geosciences11080348, 2021.
    18. Dos Santos, A. A., J. L. M. de Souza, and S. L. K. Rosa, Evapotranspiration with the Moretti-Jerszurki-Silva model for the Brazilian subtropical climate, Hydrological Sciences Journal, 66(16), 2267-2279, doi:10.1080/02626667.2021.1988610, 2021.
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  1. N. Malamos, and D. Koutsoyiannis, Bilinear surface smoothing for spatial interpolation with optional incorporation of an explanatory variable. Part 2: Application to synthesized and rainfall data, Hydrological Sciences Journal, 61 (3), 527–540, doi:10.1080/02626667.2015.1080826, 2016.

    The non-parametric mathematical framework of Bilinear Surface Smoothing (BSS) methodology provides flexible means for spatial (two dimensional) interpolation of variables. As presented in a companion paper, interpolation is accomplished by means of fitting consecutive bilinear surfaces into a regression model with known break points and adjustable smoothing terms defined by means of angles formed by those bilinear surfaces. Additionally, the second version of the methodology (BSSE) incorporates, in an objective manner, the influence of an explanatory variable available at a considerable denser dataset. In the present study, both versions are explored and illustrated using both synthesized and real world (hydrological) data, and practical aspects of their application are discussed. Also, comparison and validation against the results of commonly used spatial interpolation methods (Inverse Distance Weighted, Spline, Ordinary Kriging and Ordinary Cokriging) is performed in the context of the real world application. In every case, the method’s efficiency to perform interpolation between data points that are interrelated in a complicated manner was confirmed. Especially during the validation procedure presented in the real world case study, BSSE yielded very good results, outperforming those of the other interpolation methods. Given the simplicity of the approach, the proposed mathematical framework overall performance is quite satisfactory, indicating its applicability for diverse tasks of scientific and engineering hydrology and beyond.

    Full text: http://www.itia.ntua.gr/en/getfile/1567/1/documents/2016HSJ_BilinearPart2Application.pdf (1817 KB)

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    See also: http://dx.doi.org/10.1080/02626667.2015.1080826

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  1. N. Malamos, and D. Koutsoyiannis, Bilinear surface smoothing for spatial interpolation with optional incorporation of an explanatory variable. Part 1:Theory, Hydrological Sciences Journal, 61 (3), 519–526, doi:10.1080/02626667.2015.1051980, 2016.

    Bilinear surface smoothing is an alternative concept which provides flexible means for spatial interpolation. Interpolation is accomplished by means of fitting a bilinear surface into a regression model with known break points and adjustable smoothing terms. Additionally, as an option, the incorporation in an objective manner, of the influence of an explanatory variable available at a considerable denser dataset is possible. The parameters involved in each case (with or without an explanatory variable) are determined by a nonparametric approach based on the generalized cross-validation (GCV) methodology. A convenient search technique of the smoothing parameters was achieved by transforming them in terms of tension parameters, with values restricted in the interval [0, 1). The mathematical framework, the computational implementation and details concerning both versions of the methodology, as well as practical aspects of their application are presented and discussed. In a companion paper, examples using both synthesized and real world (hydrological) data are presented to illustrate the methodology. The proposed mathematical framework constitutes a simple alternative to existing spatial interpolation methodologies.

    Full text: http://www.itia.ntua.gr/en/getfile/1566/1/documents/2016HSJ_Bilinear_Part1Theory.pdf (188 KB)

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  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

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    8. Dimitriadou, S., and K. G. Nikolakopoulos, Artificial neural networks for the prediction of the reference evapotranspiration of the Peloponnese Peninsula, Greece, Water, 14(13), 2027, doi:10.3390/w14132027, 2022.
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  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

    Works that cite this document: View on Google Scholar or ResearchGate

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

    1. Hodam, S., S. Sarkar, A.G.R. Marak, A. Bandyopadhyay, and A. Bhadra, Spatial interpolation of reference evapotranspiration in India: Comparison of IDW and Kriging methods, Journal of The Institution of Engineers (India): Series A, 98(4), 551-524, doi:10.1007/s40030-017-0241-z, 2017.
    2. Deng, H., and J. Shao, Evapotranspiration and humidity variations in response to land cover conversions in the Three Gorges Reservoir Region, Journal of Mountain Science, 15(3), 590–605, doi:10.1007/s11629-016-4272-0, 2018.
    3. Giménez, P. O., and S. G. García-Galiano, Assessing Regional Climate Models (RCMs) ensemble-driven reference evapotranspiration over Spain, Water, 10(9), 1181, doi:10.3390/w10091181, 2018.
    4. Zhang, T., Y. Chen, and K. Tha Paw U, Quantifying the impact of climate variables on reference evapotranspiration in Pearl River Basin, China, Hydrological Sciences Journal, doi:10.1080/02626667.2019.1662021, 2019.

  1. N. Malamos, and D. Koutsoyiannis, Broken line smoothing for data series interpolation by incorporating an explanatory variable with denser observations: Application to soil-water and rainfall data, Hydrological Sciences Journal, doi:10.1080/02626667.2014.899703, 2015.

    Broken line smoothing is a simple technique for smoothing a broken line fit to observational data and provides flexible means for interpolation. Here an extension of this technique is proposed, which can be utilized to perform various interpolation tasks, by incorporating, in an objective manner, an explanatory variable available at a considerably denser dataset than the initial main variable. The technique incorporates smoothing terms with adjustable weights, defined by means of the angles formed by the consecutive segments of two broken lines. The mathematical framework and details of the method as well as practical aspects of its application are presented and discussed. Also, examples using both synthesized and real world (soil water dynamics and hydrological) data are presented to explore and illustrate the methodology.

    Full text: http://www.itia.ntua.gr/en/getfile/1436/1/documents/2014HSJ_BrokenLineSmoothing.pdf (507 KB)

    Additional material:

    See also: http://dx.doi.org/10.1080/02626667.2014.899703

    Works that cite this document: View on Google Scholar or ResearchGate

Book chapters and fully evaluated conference publications

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, Extreme rainfall modelling for the design of hydraulic works and dams: the new methodology and its application in Greece [Invited talk], Proceedings of 4th Hellenic Conference on Dams and Reservoirs, War Museum Athens, doi:10.13140/RG.2.2.24009.35689, Hellenic Commission on Large Dams, Athens, 2024.

    Full text: http://www.itia.ntua.gr/en/getfile/2479/1/documents/OmbrianDamConference2.pdf (3829 KB)

  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 "Panta Rhei", 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.

    Additional material:

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

    1. da Silva Júnior, J. C. , V. Medeiros, C. Garrozi, A. Montenegro, and G. E. Gonçalves, Random forest techniques for spatial interpolation of evapotranspiration data from Brazilian’s Northeast, Computers and Electronics in Agriculture, 166, 105017, doi:10.1016/j.compag.2019.105017, 2019.
    2. Haftcheshmeh, E. I., and F. Bansouleh, Spatial variation of reference evapotranspiration in Kermanshah province, Journal of Agricultural Meteorology, 9(2), 61-66, doi:10.22125/agmj.2021.262567.1106, 2021.

Conference publications and presentations with evaluation of abstract

  1. T. Iliopoulou, D. Koutsoyiannis, N. Malamos, A. Koukouvinos, P. Dimitriadis, N. Mamassis, N. Tepetidis, and D. Markantonis, A stochastic framework for rainfall intensity-timescale-return period relationships regionalized over Greece, European Geosciences Union General Assembly 2024, Vienna, Austria & Online, EGU24-9043, doi:10.5194/egusphere-egu24-9043, 2024.

    We develop a regionalization framework for rainfall intensity-timescale-return period relationships that is implemented across the Greek territory. The methodology for single-site estimation is based on a stochastic framework for multi-scale rainfall intensity modeling. Five parameters are first independently fitted for each site, and the resulting parameter variability is explored in terms of uncertainty and spatial variability patterns. Two parameters, the tail-index and a timescale parameter, are identified as constant in space and estimated using data pooling techniques. The remaining three parameters are regionalized across Greece using a combination of spatial interpolation and smoothing techniques, which are evaluated using cross-validation in a multi-model framework.

    Full text:

    See also: https://meetingorganizer.copernicus.org/EGU24/EGU24-9043.html

  1. T. Iliopoulou, D. Koutsoyiannis, A. Koukouvinos, N. Malamos, N Tepetidis, D. Markantonis, P. Dimitriadis, and N. Mamassis, Regionalized design rainfall curves for Greece, European Geosciences Union General Assembly 2023, Vienna, Austria & Online, EGU23-8740, doi:10.5194/egusphere-egu23-8740, 2023.

    We perform a large-scale assessment of the probabilistic behaviour of rainfall extremes over the Greek territory aiming to construct a national model for design rainfall. To this aim, we employ multiple sources of rainfall data: from long-term daily records to samples of multi-scale annual maxima, reanalysis rainfall products and satellite information. We identify suitable probability distributions for the multi-scale rainfall extremes useful for design rainfall estimation and regionalize their parameters over Greece using two-dimensional multivariate smoothing techniques. Unique insights are derived regarding the spatio-temporal variability of extreme rainfall over the Greek area, notable for its highly variable topography and climate.

    Full text: http://www.itia.ntua.gr/en/getfile/2295/1/documents/EGU23-8740-print.pdf (287 KB)

    See also: https://meetingorganizer.copernicus.org/EGU23/EGU23-8740.html

  1. A. Efstratiadis, N. Mamassis, A. Koukouvinos, D. Koutsoyiannis, K. Mazi, A. D. Koussis, S. Lykoudis, E. Demetriou, N. Malamos, A. Christofides, and D. Kalogeras, Open Hydrosystem Information Network: Greece’s new research infrastructure for water, European Geosciences Union General Assembly 2020, Geophysical Research Abstracts, Vol. 22, Vienna, EGU2020-4164, doi:10.5194/egusphere-egu2020-4164, 2020.

    The Open Hydrosystem Information Network (OpenHi.net) is a state-of-the-art information infrastructure for the collection, management and free dissemination of hydrological and environmental information related to Greece’s surface water resources. It was launched two years ago as part of the national research infrastructure “Hellenic Integrated Marine Inland water Observing, Forecasting and offshore Technology System” (HIMIOFoTS), which also comprises a marine-related component (https://www.himiofots.gr/). The OpenHi.net system receives and processes real-time data from automatic telemetric stations that are connected to a common web environment (https://openhi.net/). In particular, for each monitoring site it accommodates stage measurements, raw and automatically post-processed. Furthermore, in some specially selected sites time series related to water quality characteristics (pH, water temperature, salinity, DO, electrical conductivity) are provided. The web platform also offers automatically-processed information in terms of discharge data, statistics, and graphs, alerts for extreme events, as well as geographical data associated with surface water bodies. At the present time, the network comprises about 20 stations. However, their number is continuously increasing, due to the open access policy of the system (the platform is fully accessible to third-parties uploading their data). In the long run, it is envisioned that a national-scale hydrometric infrastructure will be established, covering all important rivers, lakes and reservoirs of the country.

    Full text:

    See also: https://meetingorganizer.copernicus.org/EGU2020/EGU2020-4164.html

  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. 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

Presentations and publications in workshops

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, Extreme rainfall modelling for engineering design: a new methodology and its application over the Greek territory (invited), Risk Management: Extremes of Flood and Drought, Europe/China, UNESCO, 2023.

    Remarks:

    Video of presentation: https://www.iahr.org/video/clip?id=1500

    Video of discussion: https://www.iahr.org/video/clip?id=1502

    Videos of the entire event: https://www.iahr.org/video/clip?id=1496

    Full text: http://www.itia.ntua.gr/en/getfile/2270/1/documents/UNESCO_China2.pdf (3617 KB)

  1. I. L. Tsirogiannis, N. Malamos, P. Barouchas, P. Baltzoi, K. Fotia, G. Tenedios, D. Giotis, D. Kateris, E. Tsoumani, S. Chiras, and A. Christofides, Evaluation of the application of the IRMA_SYS irrigation DSS on kiwi crop, 28th Conference of the Hellenic Horticulture Science Company, Thessaloniki, 465–468, October 2017.

    Full text: http://www.itia.ntua.gr/en/getfile/2013/1/documents/irma_sys_dss_aktinidio.pdf (363 KB)

Academic works

  1. N. Malamos, Methodology development for spatial interpolation of hydrometeorological variables using broken line smoothing techniques, Postgraduate Thesis, 124 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, 2000.

    Full text: http://www.itia.ntua.gr/en/getfile/465/1/documents/2000malamos.pdf (13219 KB)

Research reports

  1. D. Koutsoyiannis, T. Iliopoulou, A. Koukouvinos, N. Malamos, N. Mamassis, P. Dimitriadis, N. Tepetidis, and D. Markantonis, Technical Report, Production of maps with updated parameters of the ombrian curves at country level (impementation of the EU Directive 2007/60/EC in Greece), Department of Water Resources and Environmental Engineering – National Technical University of Athens, 2023.

    Related project: Production of maps with updated parameters of the ombrian curves at country level (implementation of the EU Directive 2007/60/EC in Greece)

    Full text: http://www.itia.ntua.gr/en/getfile/2273/1/documents/ntua_ombrian_reportF4.pdf (12849 KB)

    Additional material:

  1. N. Malamos, and I. Nalbantis, Analysis of the water demand management practices, Integrated Management of Hydrosystems in Conjunction with an Advanced Information System (ODYSSEUS), Contractor: NAMA, Report 15, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, June 2005.

    The present technical report analyzes water demand and measures and works for water demand management. The objective of the report is to define the methodological framework, within which water demand management is considered part of the information system ODYSSEUS.

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

    Full text: http://www.itia.ntua.gr/en/getfile/671/1/documents/report_15.pdf (1259 KB)