Efthymios I. Nikolopoulos

Efthymios I. Nikolopoulos
Florida Institute of Technology · Department of Mechanical and Civil Engineering

Ph.D

About

158
Publications
29,437
Reads
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2,704
Citations
Additional affiliations
February 2013 - present
University of Padova
Position
  • Marie Curie Postdoctoral Fellow
January 2012 - present
University of Padova
Position
  • PostDoc Position
January 2008 - December 2010
Hellenic Centre for Marine Research
Position
  • Researcher

Publications

Publications (158)
Article
Sub-Saharan Africa’s economy and livelihood are primarily dependent on agriculture, which makes it highly vulnerable to the impacts of extreme weather events and climate change. Modelling and quantifying extreme rainfall and its temporal changes in such environments could thus provide crucial information for design, insurance, management, ecology a...
Presentation
Full-text available
The quantification of future flood risk, as well as the assessment of impacts attributed to the evolution of extreme rainfall events under rapidly changing climatic conditions, require multi-year information at adequately high spatiotemporal scales. The spatial and temporal evolution of regional extreme rainfall patterns, however, is quite challeng...
Article
Full-text available
Accumulating evidence on the impact of climate change on droughts, highlight the necessity for developing effective adaptation and mitigation strategies. Changes in future drought risk and severity in Australia are quantified by analyzing nine CMIP6 climate models. Historic conditions (1981-2014) and projections for mid-century (2015-2050) and end-...
Conference Paper
The analysis of short-duration precipitation extremes is of foremost importance as heavy precipitation is directly related to many hazards, e.g. flash floods, landslides and crop damage. Here, we adopt an extreme value framework based on the concept of ordinary events, defined as independent realizations of the process of interest. In particular, w...
Article
Full-text available
Given the rapidly changing climate, accurate spatiotemporal information on the evolution of extreme rainfall events is required for flood risk assessment and the design of resilient infrastructure. Consequently, various research efforts have focused on investigating the appropriateness of various parametric and non-parametric approaches in modellin...
Article
Existing abiotic and biotic threats to plant species (e.g., disease, drought, invasive species) affect their capacity to recover post‐fire. We use a new, globally applicable framework to assess the vulnerability of 26,062 Australian plant species to a suite of active threats after the 2019–2020 fires. Australia. 2019–2020. Plants. Spatial data for...
Article
Flood prediction across scales and more specifically in ungauged areas remains a great challenge that limits the efficiency of flood risk mitigation strategies and disaster preparedness. Building upon the recent success of Machine Learning (ML) models on streamflow prediction, this work presents a prototype ML-based framework for flood warning and...
Article
Full-text available
The extreme rainfall during 21–22 July 2012 brought the heaviest rain to Beijing (190 mm) and Fangshan (460 mm) in six decades, which caused widespread damage in the city and its surroundings. To understand the evolution of spatio-temporal variability of precipitation and to quantify the inherent uncertainties in short-range weather forecasts of su...
Article
Full-text available
Accurate quantitative precipitation forecasts are essential for water resources management, agriculture, and other applications. Soil moisture is among the most important boundary conditions affecting the overlying atmosphere. It can affect precipitation either directly via evapotranspiration, affecting the moisture supply to the atmosphere, or ind...
Conference Paper
The analysis of precipitation extremes serves as a basis for hydraulic/hydrologic engineering, risk assessment and policy making. Climate change has resulted in significant modification (increase) of precipitation extremes. While many studies have demonstrated and quantified these changes by analyzing the tails of precipitation distributions using...
Article
Accurate, reliable, and high spatio-temporal resolution precipitation data are vital for many applications, including the study of extreme events, hydrological modeling, water resource management, and hydroclimatic research in general. In this study, we performed a systematic review of the available literature to assess the performance of the Integ...
Article
Full-text available
Biodiversity contributes to the ecological and climatic stability of the Amazon Basin1,2, but is increasingly threatened by deforestation and fire3,4. Here we quantify these impacts over the past two decades using remote-sensing estimates of fire and deforestation and comprehensive range estimates of 11,514 plant species and 3,079 vertebrate specie...
Article
Accurate characterization of soil state is imperative for weather and climate research, hydrological modeling, agriculture, water resources management, and drought monitoring. Limited-area data assimilation (DA) systems can provide high-resolution real-time soil state analyses. However, soil state representations from regional continuously cycling...
Data
The spatiotemporal character of rainfall is particularly important for hydrologic modeling, as well as hydroclimatic risk estimation and impact assessment. Existing atmospheric reanalysis datasets offer extensive record lengths and global coverage, but usually their spatial resolution is coarse for distributed hydrologic simulations at small spatia...
Article
Full-text available
The spatiotemporal character of rainfall is particularly important for hydrologic modeling, as well as hydroclimatic risk estimation and impact assessment. Existing atmospheric reanalysis datasets offer extensive record lengths and global coverage, but usually their spatial resolution is coarse for distributed hydrologic simulations at small spatia...
Article
Full-text available
Considering the reduction of steep power ramps caused by renewable energy penetration, the present study evaluates the potential of utilizing existing water supply infrastructure as small-scale pumped-hydroelectric storage (PHS) units. A novel methodology is developed that estimates the total storage capacity via the available space in five water s...
Article
Full-text available
The changing climate and anthropogenic activities raise the likelihood of damage due to compound flood hazards, triggered by the combined occurrence of extreme precipitation and storm surge during high tides and exacerbated by sea-level rise (SLR). Risk estimates associated with these extreme event scenarios are expected to be significantly higher...
Article
Full-text available
The spatial and temporal scale of flash flood occurrence provides limited opportunities for observations and measurements using conventional monitoring networks, turning the focus to event-based, post-disaster studies. Post-flood surveys exploit field evidence to make indirect discharge estimations, aiming to improve our understanding of hydrologic...
Article
Full-text available
The increasing availability of global observation datasets, both from in situ and remote sensors, and advancements in earth system models and data assimilation algorithms have generated a number of water resources reanalysis products that are available at global scale and high spatial and temporal resolutions. These products hold great potential fo...
Article
Precipitation extremes and associated hydrological hazards pose a significant global risk to society and economy. To be effective, mitigation strategies require the best possible estimation of the intensity and frequency of precipitation extremes. Traditional approaches to precipitation frequency analysis rely on long-term records from in-situ obse...
Article
Full-text available
Long-term plot-scale studies have found water limitation to be a key factor driving ecosystem productivity in the Rocky Mountains. Specifically, the intensity of early summer (the ‘foresummer’ period from May to June) drought conditions appears to impose critical controls on peak ecosystem productivity. This study aims to (1) assess the importance...
Preprint
Full-text available
The changing climate and adverse anthropogenic activities raise the likelihood of damages due to compound flood hazards, triggered by the combined occurrence of extreme precipitation and storm surge during high tides, and exacerbated by sea-level rise (SLR). Risk estimates associated with these extreme event scenarios are expected to be significant...
Article
The present study uses hourly rainfall measurements from 36 raingauge stations in the northeastern United States with more than 55 years of recordings, to assess the accuracy and robustness of three conceptually different parametric approaches to produce intensity-duration-frequency (IDF) curves from rainfall records: (a) the well celebrated parame...
Article
Full-text available
An improved understanding of changes in flood hazard and the underlying driving mechanisms is critical for predicting future changes for better adaptation strategies. While recent increases in flooding across the world have been partly attributed to a range of atmospheric or landscape drivers, one often-forgotten driver of changes in flood properti...
Article
Water resources reanalysis (WRR) can be used as a numerical tool to advance our understanding of hydrological processes where in situ observations are limited. However, WRR products are associated with uncertainty that needs to be quantified to improve usability of such products in water resources applications. In this study, we evaluate estimates...
Article
Accurately assessing flood hazards requires a better understanding of the feedbacks between natural and human influences on the characteristics of rivers.
Conference Paper
Full-text available
The New England region exhibits an increasing rate of both rooftop and major solar photovoltaic systems. Given the ambitious renewable energy goals established by the New England States, new projects for inland and offshore solar and wind farms are surging. These renewable energy penetration plans will increase the dependence of electricity supply...
Article
Full-text available
The great success of the Tropical Rainfall Measuring Mission (TRMM) and its successor Global Precipitation Measurement (GPM) has accelerated the development of global high-resolution satellite-based precipitation products (SPP). However, the quantitative accuracy of SPPs has to be evaluated before using these datasets in water resource applications...
Article
Full-text available
The current statistical methods applied in flood frequency analysis require long data records to obtain reliable estimates, particularly for long return periods. Moreover, the choice of the statistical model and the parameter estimation procedure may introduce uncertainty in the estimates. In this work, we investigate the sensitivity of flood frequ...
Article
Full-text available
This study evaluates a machine learning-based precipitation ensemble technique (MLPET) over three mountainous tropical regions. The technique, based on Quantile Regression Forests, integrates global satellite precipitation datasets from CMORPH, PERSIANN, GSMaP (V6), and 3B42 (V7) and an atmospheric reanalysis precipitation product (EI_GPCC) with da...
Article
Full-text available
Digital Terrain analysis (DTA) and modeling has been a flourishing interdisciplinary field for decades, with applications in hydrology, geomorphology, soil science, engineering projects and computer sciences. Currently, DTA is characterized by a proliferation of multispectral data from new sensors and platforms, driven by regional and national gove...
Article
Full-text available
This study focuses on the Iberian Peninsula and investigates the propagation of precipitation uncertainty, and its interaction with hydrologic modeling, in global water resource reanalysis. Analysis is based on ensemble hydrologic simulations for a period spanning 11 years (2000-2010). To simulate the hydrological variables of surface runoff, sub-s...
Poster
Full-text available
The spatial and temporal scale of flash flood occurrence provides limited opportunities for measurements and observations using of conventional monitoring networks. These observational difficulties, often accompanied by a lack of instrumental data have turned the focus to event-based, post-disaster studies. Post-flood surveys are particularly usefu...
Conference Paper
Full-text available
Hydrologic impact assessment requires accurate estimates of precipitation at temporal and spatial scales suitable to run distributed hydrologic models. In this context, multiyear global atmospheric reanalysis datasets form an important source of information in ungauged areas, mostly due to their global coverage and available record lengths that typ...
Poster
Full-text available
Hydrologic impact assessment requires accurate estimates of precipitation at temporal and spatial scales suitable to run distributed hydrologic models. In this context, multiyear global atmospheric reanalysis datasets form an important source of information in ungauged areas, mostly due to their global coverage and available record lengths that typ...
Article
Information on extreme precipitation is essential to managing weather-related risks and designing hydraulic structures. Research attention to frequency analyses based on remotely sensed precipitation datasets, such as those obtained from weather radars and satellites, has been rapidly increasing owing to their potential to provide information for u...
Article
The lack of knowledge on precipitation frequency over ungauged areas introduces a significant source of uncertainty in relevant engineering designs and risk estimation procedures. Radar-based observations offer precipitation information over ungauged areas and thus have gained increasing attention as a potential solution to this problem. However, d...
Article
Full-text available
Worldwide, many river floodplains contain critical infrastructure that is vulnerable to extreme hydrologic events. These structures are designed based on flood frequency analysis aimed at quantifying the magnitude and recurrence of the extreme events. This research topic focuses on estimating flood vulnerability at ungauged locations based on an in...
Article
Of the boundary conditions that affect the simulation of convective precipitation, soil moisture is one of the most important. In this study, we explore the impact of the soil moisture on convective precipitation, and factors affecting it, through an extensive numerical experiment based on four convective precipitation events that caused moderate t...
Poster
Full-text available
On November 15 2017, a high intensity storm, reaching 300mm in 13 hours, hit the western part of the region of Attica in Greece, causing a catastrophic flash flood in the town of Mandra and Nea Peramos, inducing 24 fatalities and extensive damages in property and infrastructure. The research team surveyed the area during and after the flood using a...
Article
Full-text available
This study focuses on the Iberian Peninsula and investigates the propagation of precipitation uncertainty, and its interaction with hydrologic modelling, in global water resources reanalysis. Analysis is based on ensemble hydrologic simulations for a period spanning 11 years (2000–2010). To simulate the hydrological variables of surface runoff, sub...
Article
On November 15 2017, a high intensity convective storm, reaching 300 mm in 13 hours in the core zone of the event, hit the western part of the region of Attica in Greece, causing a catastrophic flash flood in the town of Mandra and a tragic loss of 24 people, making it the most deadly flood in the country, in a period of 40 years. The research tea...
Article
Full-text available
Rainfall-induced debris flows in recently burned mountainous areas cause significant economic losses and human casualties. Currently, prediction of post-fire debris flows is widely based on the use of power-law thresholds and logistic regression models. While these procedures have served with certain success in existing operational warning systems,...
Article
Full-text available
In mountain basins, the use of long-range operational weather radars is often associated with poor quantitative precipitation estimation due to a number of challenges posed by the complexity of terrain. As a result, the applicability of radar-based precipitation estimates for hydrological studies is often limited over areas that are in close proxim...
Article
This study expands the Metastatistical Extreme Value (MEV) framework to sub-daily rainfall frequency analysis and compares it to extreme value theory methods in presence of short records and measurement errors. Ordinary events are identified based on the temporal autocorrelation of hourly data and modeled with a Weibull distribution. MEV is compare...
Article
The estimation of heavy precipitation events is a particularly difficult task, especially over high mountainous terrain typically associated with scant availability of in situ observations. Therefore, quantification of precipitation variability in such data-limited regions relies on remote sensing estimates, due to their global coverage and near re...
Poster
Full-text available
On November 15th 2017, a high intensity convective storm with orographic effects reaching up to 300mm in 8 hours (200mm in 3 hours only) locally in a small area (18 km x 4 km zone) of a mountain slope hit the western part of the region of Attica in Greece, causing flash floods with catastrophic effects in the towns of Mandra and Nea Peramos and the...
Conference Paper
Full-text available
Rainfall frequency analysis is crucial for hydrological design and flood risk management and relies on long records of rain gauge measurements. The recent developments in remote sensing of precipitation, as well as the deployment of new rain gauge networks in previously ungauged regions, provide rainfall information with unprecedented detail, calli...
Article
Full-text available
Rainfall-induced debris flows in recently burned mountainous areas cause significant economic losses and human casualties. Currently, prediction of post-fire debris flows is widely based on the use of power-law thresholds and logistic regression models. While these procedures have served with certain success in existing operational warning systems,...
Article
Full-text available
This study investigates the use of a nonparametric, tree-based model, quantile regression forests (QRF), for combining multiple global precipitation datasets and characterizing the uncertainty of the combined product. We used the Iberian Peninsula as the study area, with a study period spanning 11 years (2000–2010). Inputs to the QRF model included...
Article
The concurrence of flash floods and debris flows is of particular concern, because it may amplify the hazard corresponding to the individual generative processes. This paper presents a coupled modelling framework for the predictions of flash flood response and of the occurrence of debris flows initiated by channel bed mobilization. The framework co...
Article
Full-text available
The performance of six satellite-based and three newly released reanalysis rainfall estimates are evaluated at daily time scale and spatial grid size of 0.25 degrees during the period of 2000 to 2013 over the Upper Blue Nile Basin, Ethiopia, with the view of improving the reliability of precipitation estimates of the wet (June to September) and sec...
Conference Paper
Ethiopia’s high inter-annual variability in local precipitation has resulted in droughts and floods that stress local communities and lead to economic and food insecurity. Better predictions of water availability can supply farmers and water management authorities with critical guidance, enabling informed water resource allocation and management de...
Conference Paper
Fire disasters affect modern societies at global scale inducing significant economic losses and human casualties. In addition to their direct impacts they have various adverse effects on hydrologic and geomorphologic processes of a region due to the tremendous alteration of the landscape characteristics (vegetation, soil properties etc). As a conse...
Conference Paper
Quantifying the uncertainty of global precipitation datasets is beneficial when using these precipitation products in hydrological applications, because precipitation uncertainty propagation through hydrologic modeling can significantly affect the accuracy of the simulated hydrologic variables. In this research the Iberian Peninsula has been used a...
Conference Paper
Full-text available
Availability of multiple global water resources reanalysis (WRR) products has provided a unique opportunity to advance understanding of terrestrial hydrologic processes at regions where in situ information is sparse or nonexistent. Africa is a continent where this aspect is particularly emphasized because it is generally characterized by sparse hyd...