Panayiotis Dimitriadis

Panayiotis Dimitriadis
National Technical University of Athens | NTUA · Department of Water Resources and Environmental Engineering

Diploma in Civil Engineering, MSc in Water Management, PhD in Stochastics

About

151
Publications
39,761
Reads
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1,040
Citations
Additional affiliations
September 2006 - October 2007
Imperial College London
Position
  • Master's Student

Publications

Publications (151)
Poster
Full-text available
In this work we apply two different rainfall regionalization techniques over Thessaly region (Greece), an area of about 13,700 km2 with different topographic and climatological characteristics, to estimate design rainfall in ungauged sites. The first methodology is the Patched Kriging technique (Libertino et al., 2018), a year-by-year application o...
Article
Full-text available
Hydroclimatic processes such as precipitation, temperature, wind speed and dew point are usually considered to be independent of each other. In this study, the cross−correlations between key hydrological−cycle processes are examined, initially by conducting statistical tests, then adding the impact of long−range dependence, which is shown to govern...
Conference Paper
Full-text available
A comparative analysis, among different predictive breach models, is introduced using the most updated dam failure database provided by Hood et al (2019). The performance of each model is estimated using an appropriate statistical index by comparing the measured peak breach flow with the modelled peak breach flow. Having applied a regression analys...
Conference Paper
Full-text available
In this study, we are suggesting a simple methodology based on Bayesian inference to couple either the results of a single hydrological model with various objective functions or the results of multiple hydrological models in order to improve the reliability of the prediction of alarming events. The methodology was tested in a case study with data o...
Article
Full-text available
The identification of the second-order dependence structure of streamflow has been one of the oldest challenges in hydrological sciences, dating back to the pioneering work of H.E Hurst on the Nile River. Since then, several large-scale studies have investigated the temporal structure of streamflow spanning from the hourly to the climatic scale, co...
Conference Paper
Full-text available
Σε αυτή τη μελέτη, προτείνουμε τη χρήση μοντέλων μηχανικής εκμάθησης όχι ως υποκατάστατο των υδρολογικών μοντέλων, αλλά ως ανεξάρτητο εργαλείο για την επαναστο­χευμένη χρήση των υδρολογικών μοντέλων σε συστήματα έγκαιρης πρόγνωσης.
Article
Full-text available
There is a widespread perception that every year wildfires are intensifying on a global scale, something that is often used as an indicator of the adverse impacts of global warming. However, from the analysis of wildfires that have occurred in the US, Canada, and Mediterranean countries, a trend that justifies this perception could not be identifie...
Article
Full-text available
Hydropower is the most widely used renewable power source worldwide. The current work presents a methodological tool to determine the hydropower potential of a reservoir based on available hydrological information. A Bayesian analysis of the river flow process and of the reservoir water volume is applied, and the estimated probability density funct...
Article
Full-text available
Machine learning has been employed successfully as a tool virtually in every scientific and technological field. In hydrology, machine learning models first appeared as simple feed-forward networks that were used for short-term forecasting, and have evolved into complex models that can take into account even the static features of catchments, imita...
Article
Full-text available
The stochastic structures of potential evaporation and evapotranspiration (PEV and PET or ETo) are analyzed using the ERA5 hourly reanalysis data and the Penman–Monteith model applied to the well-known CIMIS network. The latter includes high-quality ground meteorological samples with long lengths and simultaneous measurements of monthly incoming sh...
Article
Full-text available
The stochastic analysis in the scale domain (instead of the traditional lag or frequency domains) is introduced as a robust means to identify, model and simulate the Hurst–Kolmogorov (HK) dynamics, ranging from small (fractal) to large scales exhibiting the clustering behavior (else known as the Hurst phenomenon or long-range dependence). The HK cl...
Article
Full-text available
We outline and test a new methodology for genuine simulation of stochastic processes with any dependence structure and any marginal distribution. We reproduce time dependence with a generalized, time symmetric or asymmetric, moving-average scheme. This implements linear filtering of non-Gaussian white noise, with the weights of the filter determine...
Article
Full-text available
Near-surface air temperature is one of the most widely studied hydroclimatic variables, as both its regular and extremal behaviors are of paramount importance to human life. Following the global warming observed in the past decades and the advent of the anthropogenic climate change debate, interest in temperature’s variability and extremes has been...
Preprint
Full-text available
We outline and test a new methodology for genuine simulation of stochastic processes with any dependence and any marginal distribution. We reproduce time dependence with a generalized, time symmetric or asymmetric, moving-average scheme. This implements linear filtering of non-Gaussian white noise, with the weights of the filter determined by analy...
Article
Lacking coastal and offshore wind speed time series of sufficient length, reanalysis data and wind speed models serve as the primary sources of valuable information for wind power management. In this study, long-length observational records and modelled data from Uncertainties in Ensembles of Regional Re-Analyses system are collected, analyzed and...
Presentation
Full-text available
Changes in the land cover occur all the time at the surface of the Earth both naturally and anthropogenically. In the last decades, certain types of land cover change, including urbanization, have been correlated to local temperature increase, but the general dynamics of this relationship are still not well understood. This work examines whether la...
Conference Paper
Full-text available
Since the pre-industrial era at the end of the 18th century, the atmospheric carbon dioxide concentration (CO2) has increased by 47.46% from the level of 280 ppmv (parts per million volume) to 412.89 ppmv (Mauna Loa – NOAA Station, November 2020). These increased concentrations caused by natural & anthropogenic activities, interact with the aquatic...
Presentation
Full-text available
In the last few years, the island of Crete (Greece - Eastern Mediterranean) has been affected by extreme events. In recent decades, hydrometeorological processes in the island of Crete are monitored by an extensive network of meteorological stations. Here we stochastically analyze the spatial stochastic structure of precipitation in the island by e...
Article
Full-text available
Time series analysis is a major mathematical tool in hydrology, with the moving average being the most popular model type for this purpose due to its simplicity. During the last 20 years, various studies have focused on an important statistical characteristic, namely the long-term persistence and the simultaneous statistical consistency at all time...
Article
Full-text available
We investigate the impact of time's arrow on the hourly streamflow process. Although time asymmetry, i.e., temporal irreversibility, has been previously implemented in stochastics, it has only recently attracted attention in the hydrological literature. Relevant studies have shown that the time asymmetry of the streamflow process is manifested at s...
Article
Full-text available
To seek stochastic analogies in key processes related to the hydrological cycle, an extended collection of several billions of data values from hundred thousands of worldwide stations is used in this work. The examined processes are the near-surface hourly temperature, dew point, relative humidity, sea level pressure, and atmospheric wind speed, as...
Article
Full-text available
In human societies, we observe a wide range of types of stratification, i.e., in terms of financial class, political power, level of education, sanctity, and military force. In financial, political, and social sciences, stratification is one of the most important issues and tools as the Lorenz Curve and the Gini Coefficient have been developed to d...
Chapter
Throughout human history, the quantification of aesthetics has intrigued philosophers, artists, and mathematicians alike. In this chapter, a methodology based on stochastic mathematics is applied for the quantification of aesthetic attributes of paintings and landscapes. The paintings analyzed include Da Vinci, Pablo Picasso, and various other cele...
Chapter
The fundamental concepts in the field of water-energy systems and their historical evolution with emphasis on recent developments are reviewed. Initially, a brief history of the relation of water and energy is presented and the concept of the water-energy nexus in the 21th century is introduced. The investigation of the relationship between water a...
Article
Full-text available
A physical process is characterized as complex when it is difficult to analyze and explain in a simple way, and even more difficult to predict. The complexity within an art painting is expected to be high, possibly comparable to that of nature. Herein, we apply a 2D stochastic methodology to images of both portrait photography and artistic portrait...
Article
Full-text available
Even though landscape quality is largely a subjective issue, the integration of infrastructure into landscapes has been identified as a key element of sustainability. In a spatial planning context, the landscape impacts that are generated by infrastructures are commonly quantified through visibility analysis. In this study, we develop a new method...
Article
Full-text available
Clustering structures appearing from small to large scales are ubiquitous in the physical world. Interestingly, clustering structures are omnipresent in human history too, ranging from the mere organization of life in societies (e.g., urbanization) to the development of large-scale infrastructure and policies for meeting organizational needs. Indee...
Article
Full-text available
Image velocimetry is a popular remote sensing method mainly because of the very modest cost of the necessary equipment. However, image velocimetry methods employ parameters that require high expertise to select appropriate values in order to obtain accurate surface flow velocity estimations. This introduces considerations regarding the subjectivity...
Preprint
Full-text available
The measurement of river discharge under various conditions is of paramount importance in hydrology. The traditional method to make a discharge measurement, and the only option until recently, is very tedious and sometimes even dangerous. For this reason, nowadays, remote sensing techniques are employed to reduce the need for traditional discharge...
Conference Paper
Full-text available
This research uses a stochastic computational tool (2D-C) for characterizing images in order to examine similarities and differences among artworks. 2D-C is measures the degree of variability (change in variability vs. scale) in images using stochastic analysis. Apparently, beauty is not easy to quantify, even with stochastic measures. The meaning...
Presentation
Full-text available
Recent research has revealed the significance of Hurst-Kolmogorov dynamics and inherent uncertainties in flood inundation and flood mapping. However, classic risk estimation for flood insurance practices is formulated under the assumption of independence between the frequency and the severity of extreme flood events, which is unlikely to be tenable...
Presentation
Full-text available
Population growth, economic development and risk-blind urbanization often increase exposure to risk, including that due to floods. While rural flooding may affect much larger areas of land, urban floods are more challenging to manage, since the higher population and asset density in the urban environment increase the environmental and social impact...
Article
Full-text available
A physical process is characterized as complex when it is difficult to analyze or explain in a simple way. The complexity within an art painting is expected to be high, possibly comparable to that of nature. Therefore, constructions of artists (e.g., paintings, music, literature, etc.) are expected to be also of high complexity since they are produ...
Article
Full-text available
Water is the basis of our civilization and the development of society is intertwined with the exploitation of water resources in various scales, from a well dug to irrigate a garden, to a large dam providing water and energy for a large area. However, for remote mountainous areas, intermittent natural water resources and high seasonal demand the ab...
Article
Full-text available
We investigate the application of a solar-powered bus route to a small-scale transportation system, as such of a university campus. In particular, we explore the prospect of replacing conventional fossil fuel buses by electric buses powered by solar energy and electricity provided by the central grid. To this end, we employ GIS mapping technology t...
Preprint
Full-text available
One of the key issues in hydrology is the estimation of streamflow, bathymetry, and water-pressure in rivers through non-invasive practices. This study investigates the streamwise velocity, pressure and water-depth spatial-deterministic profiles in a cross-section under incompressible one-dimensional steady-flow dynamics. We implement a probabilist...
Preprint
Full-text available
We apply the revisited maximum-entropy framework developed in Dimitriadis et al. (2019b), where theoretical profiles for the longitudinal velocity, pressure and water-depth in natural cross-sections under one-dimensional steady flow dynamics are derived. The maximum entropy distribution is applied to each variable of interest-based on the number of...
Article
Full-text available
Geophysical processes are often characterized by long-term persistence. An important characteristic of such behaviour is the induced large statistical bias, i.e. the deviation of a statistical characteristic from its theoretical value. Here, we examine the most probable value (i.e. mode) of the estimator of variance to adjust the model for statisti...
Article
Full-text available
Renewable energy (RE) installations and civil works are beneficial in terms of sustainability, but a considerable amount of space in the landscape is required in order to harness this energy. In contemporary environmental theory the landscape is considered an environmental parameter and the transformation of the landscape by RE works has received i...
Poster
Full-text available
Stochastics help develop a unified perception for natural phenomena and expel dichotomies like random vs. deterministic, as both randomness and predictability coexist and are intrinsic to natural systems which can be deterministic and random at the same time, depending on the prediction horizon and the time scale. The high complexity and uncertaint...
Poster
Full-text available
Decisions on technical issues must simultaneously satisfy several conflicting objectives. Several methods have been developed to help identify the "optimal" decision. Such decisions are made by politicians but experts, constructors and the society must have the ability to overview and influence these decisions. The interaction of the different grou...
Poster
Full-text available
Temperature, as one of the most important hydroclimatic variables, affects all aspects of human life. Agriculture, trade, transportation, energy production and consumption, all depend to some degree on surface temperature and its probability distribution. This distribution is commonly assumed as Gaussian but little research has been done to investi...
Research
Full-text available
In technical problems where decisions must simultaneously satisfy several conflicting objectives, methods are based on benefit-cost analysis or multicriteria decision analysis helpful to identify the “optimal” decision. Usually big technical decisions are made by politics and influence the environment, but specialists, constructors and the society...
Poster
Full-text available
In the era of rapid technological advancements, innovations have started to reshape the field of transportation and energy management. University Campuses are considered as the ideal venue for implementing and testing innovative transportation services, as they usually encompass a closed form small-scale transportation infrastructure, and mainly in...
Poster
Full-text available
We explore the prospect of replacing conventional university campus buses powered by fossil fuels with ones using solar energy. The proposed research investigates the emerging technology of solar powered road panels within a stochastic framework in order to optimally determine the corresponding infrastructure requirements for a university circulato...
Poster
Full-text available
During the last decades, the rising demand for crops for human consumption and industrial processes has led to a growth of investments and search for innovative solutions across the field of agriculture. However, one major risk that both investors and low-income farmers encounter worldwide is the impact of extreme weather events on their crop yield...
Poster
Full-text available
We investigate the recently published CAMELS dataset, which is one of the most comprehensive large-scale datasets in terms of river flow timeseries and attributes of catchments minimally impacted by human activities. We examine the stochastic properties of daily river flow and rainfall series and investigate the links between the two at various lag...
Poster
Full-text available
Ocean energy is considered a promising renewable energy resource mainly due to its massive energy potential. State of the art technologies that can harness the ocean dynamics are discussed in terms of their efficiency and cost of energy production. The ocean related process with the highest potential, but also the highest uncertainty, is the wave p...
Poster
Ocean energy is considered a promising renewable energy resource mainly due to its massive energy potential. State of the art technologies that can harness the ocean dynamics are discussed in terms of their efficiency and cost of energy production. The ocean related process with the highest potential, but also the highest uncertainty, is the wave p...
Article
Full-text available
Determining the geophysical properties of rocks and geological formations is of high importance in many fields such as geotechnical engineering. In this study, we investigate the second-order dependence structure of spatial (two-dimensional) processes through the statistical perspective of variance vs. scale (else known as the climacogram) instead...
Article
Full-text available
In February 2017, a failure occurring in Oroville Dam’s main spillway risked causing severe damages downstream. A unique aspect of this incident was the fact that it happened during a flood scenario well within its design and operational procedures, prompting research into its causes and determining methods to prevent similar events from reoccurrin...
Article
Full-text available
The ever-increasing energy demand has led to overexploitation of fossil fuels deposits, while renewables offer a viable alternative. Since renewable energy resources derive from phenomena related to either atmospheric or geophysical processes, unpredictability is inherent to renewable energy systems. An innovative and simple stochastic tool, the cl...
Article
Full-text available
Since the beginning of the 21st century, the scientific community has made huge leaps to exploit renewable energy sources, with solar radiation being one of the most important. However, the variability of solar radiation has a significant impact on solar energy conversion systems, such as in photovoltaic systems, characterized by a fast and non-lin...
Conference Paper
In this work, several stochastic input series (for different second-order dependence structures) are applied to a benchmark mixed river geometry using a hydrodynamic model, and the resulted stochastic output behaviour is investigated.