Demetris Koutsoyiannis

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• Civil Engineer, Doctor in Engineering
• Professor Emeritus at National Technical University of Athens

According to the traditional notion of randomness and uncertainty, natural phenomena are separated into two mutually exclusive components, random (or stochastic) and deterministic. Within this dichotomous logic, the deterministic part supposedly represents cause-effect relationships and, thus, is physics and science (the "good"), whereas randomness...

Some known results from statistical thermophysics as well as from hydrology are revisited from a different perspective trying: (a) to unify the notion of entropy in thermodynamic and statistical/stochastic approaches of complex hydrological systems and (b) to show the power of entropy and the principle of maximum entropy in inference, both deductiv...

Since “panta rhei” was pronounced by Heraclitus, hydrology and the objects it studies, such as rivers and lakes, have offered grounds to observe and understand change and flux. Change occurs on all time scales, from minute to geological, but our limited senses and life span, as well as the short time window of instrumental observations, restrict ou...

The old principle of parsimonious modelling of natural processes has regained its importance in the last few years. The inevitability of uncertainty and risk, and the value of stochastic modelling in dealing with them, are also again appreciated, after a period of growing hopes for radical reduction of uncertainty. Yet in stochastic modelling of na...

As a result of technological advances in monitoring atmosphere, hydrosphere, cryosphere and biosphere, as well as in data management and processing, several databases have become freely available. These can be exploited in revisiting the global hydrological cycle with the aim, on the one hand, to better quantify it and, on the other hand, to test t...

Several comments were posted to this essay. However, as of 1 May 2025, ResearchGate removed both the option to enter comments and the existing comments. I had saved some of them, which I include in the attached file. [See https://help.researchgate.net/hc/en-us/articles/33255035546257 ]

Flood events, exacerbated by climate variability, pose significant challenges to flood risk management and the insurance industry in the United States. To enhance flood risk modeling strategies, this study employs machine learning to predict regions prone to high flood insurance claims by integrating hydrological, meteorological, and socio-economic...

Our revisit of fundamental issues of climate challenges the notion and term of the “greenhouse effect”, and attempts a scientific reevaluation using minimal assumptions, such as Newton’s laws, maximum entropy and gas spectroscopy. It replaces terms like “greenhouse gas” with “radiatively active gas” (RAG) and “greenhouse effect” with “atmospheric r...

Video and presentation also available at: https://klimath.substack.com/p/international-hellenic-association and https://www.itia.ntua.gr/2528/

This study introduces a global clustering approach for reference evapotranspiration (ETo) based on spectral clustering techniques. By analyzing 3139 stations worldwide, the method segments the globe into 45 unique clusters that reflect shared ETo dynamics. This clustering technique not only enhances the accuracy of ETo estimation but also provides...

https://ui.adsabs.harvard.edu/abs/2024EGUGA..2612686D/abstract

An extension of the BLUECAT approach and software for uncertainty assessment of environmental predictions is presented, allowing the application to multimodel outputs. BLUECAT operates by transforming a point prediction provided by deterministic models to a corresponding stochastic formulation, thereby allowing the estimation of a bias corrected ex...

Amid the growing energy–water nexus crisis, large dams are being reconsidered as viable solutions despite significant environmental concerns. A critical and enduring issue with large dams is the threat they pose to downstream communities and infrastructure in the event of structural failure. The Oroville Dam spillway incident, where inadequate main...

A novel metric for rainfall-runoff model calibration and performance assessment is proposed. By integrating entropy and mutual information concepts as well as uncertainty quantification through BLUECAT (likelihood-free approach), RUMI (Ratio of Uncertainty to Mutual Information) offers a robust framework for quantifying the shared information betwe...

The Nash–Sutcliffe efficiency remains the best metric for measuring the appropriateness of a model and reflects a culture developed in hydrology to test models against reality before using them. This metric is not without problems, and alternative metrics have been proposed subsequently. Here, the concept of knowable moments is exploited to provide...

Amid concerns of intensified water cycle during global warming, the scientific attention on rainfall dynamics and its extremes is increasing. Global trends in rainfall totals and extremes are investigated using long-term rainfall station data-spanning more than 150 years for rainfall maxima and more than 200 years for total annual totals, as well a...

As cities have expanded into floodplains, the need for their protection has become crucial, prompting the evolution of flood studies. Here, we describe the operational tools, methods and processes used in flood risk engineering studies in the 1970s, and we evaluate the technological progress up to the present day. To this aim, we reference relevant...

[* The electronic version of the book is freely available with a Creative Commons licence (CC BY-NC-ND 4.0). For a print version, see http://www.itia.ntua.gr/2000/ *] Much is said and written about hydroclimatic hazards: storms, floods, droughts. Such hazards have existed and will always exist, while the usual scaremongering on them is of little...

The Nash–Sutcliffe efficiency remains the best metric of the appropriateness of a model, and reflects a culture developed in hydrology to test models against reality before using them. This metric is not without problems and alternative metrics have been proposed subsequently. Here the concept of knowable moments is exploited to provide robust metr...

Human-produced CO₂ by fossil fuel combustion, combined with the rising atmospheric CO₂ concentration and the observed temperature increase, enabled a compelling narrative to be constructed , in which these three facts, in that order, formed a chain of causality. The narrative has been embraced by global political elites to promote their interests....

Forests are essential not only for their ecological roles but also as invaluable natural resources supporting biodiversity, climate regulation, and human livelihoods. In Mediterranean regions, pine-tree forests are particularly susceptible to intense wildfires, which pose significant challenges to containment and long-term forest health. This study...

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...

The Nile has given not only material gifts to Egypt and the world, but also intellectual gifts to science, especially to geoscience. The Nile still has much to teach science-especially about climatology, as it reflects climatic behaviors over vast areas in tropical and subtropical zones. These climatic behaviors have been documented across time wit...

Human-produced CO₂ by fossil fuel combustion, combined with the rising atmospheric CO₂ concentration and the observed temperature increase, enabled a compelling narrative to be constructed, in which these three facts, in that order, formed a chain of causality. The narrative was embraced by global political elites to promote their interests and bec...

Using a detailed atmospheric radiative transfer model, we derive macroscopic relationships of downwelling and outgoing longwave radiation which enable determining the partial derivatives thereof with respect to the explanatory variables that represent the greenhouse gases. We validate these macroscopic relationships using empirical formulae based o...

This file is the Supplementary Information of the paper "Relative importance of carbon dioxide and water in the greenhouse effect: Does the tail wag the dog?" It contains interesting material as it demonstrates the current practices of silencing voices that disagree with mainstream opinions, which are purported to be science. The contained materia...

Prompted by post-publication comments on my recent paper “Refined reservoir routing (RRR) and its application to atmospheric carbon dioxide balance”, I present a multi-compartment carbon balance model whose results turn out to agree with those in the paper and disagree with IPCC’s official ones. I also discuss an additional approach, which is popul...

Recent studies have shown the potential of transformer-based neural networks in increasing prediction capacity. However, classical transformers present several problems such as computational time complexity and high memory requirements, which make Long Sequence Time-Series Forecasting (LSTF) challenging. The contribution to the prediction of time s...

Careful inspection of the title and graphical abstract of the original paper would have eased the concerns expressed by Kleber in his Comment. The title of the original paper clarifies that it examines the period since the Little Ice Age, and during this period no change was found in the net isotopic signature of atmospheric CO2 sources and sinks....

An extension of the BLUECAT approach and software for uncertainty assessment of environmental predictions is presented, allowing the application to multimodel outputs. BLUECAT operates by transforming a point prediction provided by deterministic models to a corresponding stochastic formulation, thereby allowing the estimation of a bias corrected ex...

Οι επιπτώσεις των έργων υποδομής στο τοπίο απασχολούν όλο και περισσότερο την κοινή γνώμη. Την τελευταία δεκαετία, ιδιαίτερη έμφαση έχει δοθεί στα αιολικά και τα φωτοβολταϊκα έργα και τις επιδράσεις τους στον φυσικό, πολιτισμικό και αισθητικό χαρακτήρα των τοπίων. Παράλληλά όμως, η προβληματική αυτή αποτέλεσε αφορμή για να έρθει στο προσκήνιο ένα σ...

Hurst’s paper on the Nile’s flow variability marked a pivotal moment in hydrology and beyond by introducing what was called the Hurst phenomenon. Independently, Kolmogorov developed a mathematical model describing this behaviour a decade earlier. The Hurst-Kolmogorov dynamics (HKd) is used to express this phenomenon physically and mathematically, w...

This file includes the review reports and author replies of the paper with final title "Refined Reservoir Routing (RRR) and Its Application to Atmospheric Carbon Dioxide Balance". It can also be accessed from the official journal's site: https://www.mdpi.com/2073-4441/16/17/2402/review_report

Reservoir routing has been a routine procedure in hydrology, hydraulics and water management. It is typically based on the mass balance (continuity equation) and a conceptual equation relating storage and outflow. If the latter is linear, then there exists an analytical solution of the resulting differential equation, which can directly be utilized...

Recent studies have shown the potential of Transformer-based neural networks in increasing prediction capacity. However, classical transformers present several problems such as computational time complexity and high memory requirements, which make Long Sequence Time-Series Forecasting (LSTF) challenging. The contribution to the prediction of time s...

Recent research highlights the importance of Hurst-Kolmogorov dynamics (else known as long-range dependence), characterized by strong correlation and high uncertainty in large scales, in flood risk assessment, particularly in the dynamics of flood occurrence and duration. While several catastrophe modeling professionals nowadays incorporate scenari...

Publishing papers that challenge conventional wisdom is not easy. I struggled to publish each one of the papers that contradict the established climate narrative. I still struggle to publish others which are being reviewed or have been rejected. The attacks may continue after publication of published papers, aiming to force publishers to retract pu...

As a result of recent research, a new stochastic methodology of assessing causality was developed. Its application to instrumental measurements of temperature (T) and atmospheric carbon dioxide concentration ([CO₂]) over the last seven decades provided evidence for a unidirectional, potentially causal link between T as the cause and [CO₂] as the ef...

The area of north Euboea is characterized by its intense relief, dense hydrographic network, and rich flora and fauna. In the mid-2010s, the region was struck by a plane tree disease that withered the large population of plane trees in the area, while in 2021, a large wildfire completely burned the forest. These unfortunate events depleted the land...

The study evaluates the rain-on-grid (RoG) hydraulic model’s sensitivity to digital elevation model (DEM) resolution when simulating an extreme flood in Slovenia. The RoG model is validated against a high-resolution benchmark, showing strong agreement with a Kling-Gupta efficiency of 0.913 and Pearson correlation of 0.964 for a 1 m DEM. Differences...

The following seven simple statements are investigated: (1) Lack of water is a threat of death—but not from thirst. (2) Humans are not fish. (3) The availability of water depends on uncontrollable natural processes. (4) Natural availability of water is not sufficient. (5) Wind and solar energy without water energy is a recipe for failure. (6) Predi...

Αναλύονται οι ακόλουθες επτά απλές διαπιστώσεις: (1) H λειψυδρία είναι απειλή θανάτου—αλλά όχι από δίψα. (2) Ο άνθρωπος δεν είναι ψάρι. (3) Η διαθεσιμότητα του νερού εξαρτάται από μη ελέγξιμες φυσικές διεργασίες. (4) Η φυσική διαθεσιμότητα νερού δεν φτάνει. (5) Ενέργεια από άνεμο και ήλιο χωρίς ενέργεια από νερό είναι συνταγή αποτυχίας. (6) Η πρόβλ...

(1) Information file for the rejection by Hydrological Sciences Journal; (2) Manuscript as submitted to MDPI Hydrology; (3) Information file for the rejection by MDPI Hydrology.

Using a detailed atmospheric radiative transfer model, we derive macroscopic relationships of downwelling and outgoing longwave radiation, useful for hydrological practice. We validate them using empirical formulae based on downwelling radiation data, which are in common use in hydrology, as well as satellite data for the outgoing radiation. We use...

This paper elucidates the development of electricity production and distribution in Greece from the 1950s to date. In this period, Greece experienced a multifaceted energy transition, including both the transition of ownership of energy generation companies, from public to private, and a transition from an energy mix in which coal (lignite) served...

As a result of recent research, a new stochastic methodology of assessing causality was developed. Its application to instrumental measurements of temperature (T) and atmospheric carbon dioxide concentration ([CO₂]) over the last seven decades provided evidence for a unidirectional, potentially causal link between T as the cause and [CO₂] as the ef...

Reservoir routing has been a routine procedure in hydrology, hydraulics and water management. It is typically based on the mass balance (continuity equation) and a conceptual equation relating storage and outflow. If the latter is linear, then there exists an analytical solution of the resulting differential equation, which can directly be utilized...

In this work, we formulate a regionalization framework for rainfall intensity–timescale–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 fir...

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 h...

Using a detailed atmospheric radiative transfer model, we derive macroscopic relationships of downwelling and outgoing longwave radiation, useful for hydrological practice. We validate them using empirical formulae based on downwelling radiation data, which are in common use in hydrology, as well as satellite data for the outgoing radiation. We use...

Highly turbulent water flows, often encountered near human constructions like bridge piers, spillways, and weirs, display intricate dynamics characterized by the formation of eddies and vortices. These formations, varying in sizes and lifespans, significantly influence the distribution of fluid velocities within the flow. Subsequently, the rapid ve...

This research investigates the intricate relationship between flood insurance claims and streamflow extremes in the contiguous USA, challenging the conventional belief of independence and non catastrophic nature of insurable flood losses. Focusing on the Hurst Kolmogorov dynamics, which emphasizes the temporal dependence of extreme flood events, we...

During the last decades, scientific research in the field of flood risk management has provided new insights and strong computational tools towards the deeper understanding of the fundamental stochastic behaviour that characterizes such natural hazards Flood hazards are controlled by hydrometeorological processes and their inherent uncertainties. H...

Storm Daniel initiated on 3 September 2023, over the Northeastern Aegean Sea, causing extreme rainfall levels for the following four days, reaching an average of about 360 mm over the Peneus basin, in Thessaly, Central Greece. This event led to extensive floods, with 17 human lives lost and devastating environmental and economic impacts. The automa...

Recent research highlights the importance of Hurst-Kolmogorov dynamics (else known as long-range dependence), characterized by strong correlation and high uncertainty in large scales, in flood risk assessment, particularly in the dynamics of flood occurrence and duration. While several catastrophe modeling professionals nowadays incorporate scenari...

Recent studies have provided evidence, based on analyses of instrumental measurements of the last seven decades, for a unidirectional, potentially causal link between temperature as the cause and carbon dioxide concentration ([CO2]) as the effect. In the most recent study, this finding was supported by analysing the carbon cycle and showing that th...

The water–energy–food (WEF) nexus is a basic element of prosperity, yet it is not equally distributed on the land. Human progress has optimized the function of the WEF nexus to bridge the inequality gap. In order to understand this progress, this study compares the preindustrial and modern agricultural practices in an area in Greece. Interviews wer...

(1) Anatomy of a plagiarized review. (2) List of 40 identified, plagiarised reviews. (3) Basic metadata from 50 reviews. (4) ChatGPT experiment #1. (5) ChatGPT experiment #2.

The phenomenon of plagiarism in peer-review evaluation reports remained surprisingly unrecognized, despite a notable rise of such cases in recent years. This study reports multiple cases of peer-review plagiarism recently detected in 50 different scientific articles published in 19 journals. Their in-depth analysis reveals that such reviews tend to...

Quantification of the greenhouse effect is a routine procedure in the framework of hydrological calculations of evaporation. According to the standard practice, this is made considering the water vapour in the atmosphere, without any reference to the concentration of carbon dioxide (CO2), which, however, in the last century has escalated from 300 t...

Μέρος Α: Νείλος και η γέννηση της επιστήμης. Μέρος Β: Επίκαιρα μαθήματα του Νείλου απ’ τα βάθη των αιώνων. Μέρος Γ: Μερικές σκέψεις με αφορμή τον Νείλο. [Part A: The Nile and the birth of science. Part B: Current lessons of the Nile from the depths of the centuries. Part C: Some thoughts inspired by the Nile.]

Ancient monuments located in urbanized areas are subject to numerous short- and long-term environmental hazards with flooding being among the most critical ones. Flood hazards in the complex urban environment are subject to large spatial and temporal variability and, thus, require location-specific risk assessment and mitigation. We devise a method...

Stakeholders in the development of renewable energy are often uncertain about whether landscape impacts are a genuine and objective issue or whether they should be attributed to biased NIMBY (not in my back yard) dispositions by the public. This uncertainty eventually conflicts with the development of effective design methods for the mitigation of...

This “book” is a copy of the blog discussion "Causality and climate" in Judith Curry’s blog "Climate Etc." taken on 2023-11-11 by Demetris Koutsoyiannis. Main post by Antonis Christofides, Demetris Koutsoyiannis, Christian Onof and Zbigniew W. Kundzewicz with a comment by Judith Curry. Featuring 989 contributions in 184 groups from 83 commenters....

«It is not the CO₂ levels that influence temperatures but the exact opposite» The Greek academic: «It's the hen or egg dilemma applied to the climate. Italy? Beautiful but it's difficult to do science.» [«Non sono i tassi di CO₂ a influenzare le temperature ma l'esatto opposto.» L'accademico greco: «È il dilemma dell'uovo e della gallina applicato...

Comprehending the correlation between alterations in human‐flood distance and flood fatalities (as well as displacements) is pivotal for formulating effective human adaptive strategies in response to floods. However, this relationship remains inadequately explored in existing global analyses. To address this gap, we examine 910 flood events occurri...

The scientific and wider interest in the relationship between atmospheric temperature (T) and concentration of carbon dioxide ([CO2]) has been enormous. According to the commonly assumed causality link, increased [CO2] causes a rise in T. However, recent developments cast doubts on this assumption by showing that this relationship is of the hen-or-...

Σχετικά με το επεισόδιο βροχής και πλημμύρας του Σεπτεμβρίου 2023 στην Ελλάδα. [Regarding the rain and flood event in Greece of September 2023.] (Περιέχονται τόσο το πλήρες ελληνικό κείμενο, όσο και η μετάφρασή του στα αγγλικά [Both the full original Greek text and its translation into English are included])

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 lowlan...

Knowable moments, abbreviated as K-moments, are redefined as expectations of maxima or minima of a number of stochastic variables that are a sample of the variable of interest. The new definition enables applicability of the concept to any type of variable, continuous or discrete, and generalization for transformations thereof. While K-moments shar...

such a holistic approach for flood risk assessment is implemented on building block level in Greece. Hence, taking into consideration the regional scale and the high spatial resolution in hydrologic and hydraulic models and flood hazards maps, detailed field visits are conducted following a specific methodology. Specifically, cross section measurem...

ΕΛΛΗΝΙΚΗ ΥΔΡΟΤΕΧΝΙΚΗ ΕΝΩΣΗ (ΕΥΕ) ΕΛΛΗΝΙΚΗ ΕΠΙΣΤΗΜΟΝΙΚΗ ΕΤΑΙΡΕΙΑ (ΕΛΛΕΠΕΤ) http://www.itia.ntua.gr/2288/

Infrastructure projects, although associated with public health and well-being, are often faced with opposition movements during their design and implementation. In this work, public involvement is investigated as means for comprehending the reasons behind any public opposition during the implementation of civil infrastructure works. More specifica...

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 Eur...

Precipitation deficits are the main physical drivers of droughts across the globe, and their level of persistence can be characterised by the Hurst coefficient H (0.5<H<1), with high H indicating strong long-term persistence (LTP). Previous analyses of point and gridded annual global precipitation datasets have concluded that LTP in precipitation i...

Εκδήλωση/συζήτηση: κλιματική κρίση ή η κρίση ως τεχνική διακυβέρνησης; Λέσχη Ανειδίκευτων, Παρασκευή 7/4/2023, ΕΜΠ-Κτίριο Αβέρωφ, http://www.itia.ntua.gr/2284/

A combination of stochastic and deterministic models is applied for the study of ocean wind waves. Timeseries of significant wave height and mean zero up-crossing period, obtained from globally scattered floating buoys, are analyzed in order to construct a double periodic model, and select an optimal marginal distribution and dependence function fo...

A presentation in conference: "MDPI World Water Day Webinar 2023: Accelerating Change" in three parts: (A) Global hydrology, (B) Hydrology of the Mediterranean, (C) Hydrology of Greece.

The water–energy–food (WEF) and land nexus is a basic element of prosperity. However, the elements of WEF are not equally distributed, and the dynamics of trading drives the distribution of goods. Money controls the trading, but money is just a convention and not a stable measure. Therefore, we have used the data of gross domestic product (GDP) and...

This paper examines the impacts of three different potential evapotranspiration (PET) models on drought severity and frequencies indicated by the standardized precipitation index (SPEI). The standardized precipitation-evapotranspiration index is a recent approach to operational monitoring and analysis of drought severity. The standardized precipita...

Social structure is based on the availability of the Water-Energy-Food Nexus. To cover these needs of society, several solutions of different scales of infrastructures coexist. The construction of infrastructure is capital-intensive; therefore, investment risk is always a consideration. In this paper, we try to evaluate the investment risk by inter...

This paper elucidates the development of electricity production and distribution in Greece from the 1950s to date, in correlation with national and European energy policy. During this period, Greece experienced a multifaceted energy transition, including both the transition of ownership of energy generation companies from public to private and a tr...

We give a brief overview of conceptions of causality and attempts to find probabilistic characterizations of it. We argue that a useful criterion for causal links in open systems would apply to time-series of causally related phenomena, and that it only makes sense to seek necessary conditions for causality. The criterion we develop uses an impuls...

Whilst several methods exist to provide sample estimates of the probability distribution function at several points, for the probability density of continuous stochastic variables, only a gross representation through the histogram is typically used. It is shown that the newly introduced concept of knowable moments (K-moments) can provide smooth emp...

A brief overview of the developments of hydrology in ancient Greek is followed by an appraisal of the conditions that allowed the developments. Comparing these conditions with modern ones we may observe or conjecture the following, with respect to contemporary times: (a) Modern western societies, unlike those in ancient Greece, dislike diversity of...

Short answer (scientific): Nothing — Short answer (official): Anything that basically covers the commitments without sacrificing scientific truth [Συνοπτική απάντηση (επιστημονική): Τίποτε — Συνοπτική απάντηση (υπηρεσιακή): Ό,τι καλύπτει στοιχειωδώς τις δεσμεύσεις χωρίς να θυσιάσουμε την επιστημονική αλήθεια]