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Dr. Elias Dimtriou
Hellenic Centre for Marine Research - Institute of Marine Biological Resources and Inland Waters

Basic Info


Research Keywords & Expertise

0 Water
0 Hydrologic and Water Resource Modeling and Simulation
0 Monitoring and Impact evaluation
0 Hydro-geomorphology
0 Pollution groundwater risk assessment

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Short Biography

Dr. Elias Dimitriou is a Researcher with expertise in Water Resources Management, pollution control and environmental monitoring. He is a Research Director at the Hellenic Center for Marine Research (HCMR). His research interests and experience include hydroecological modeling; water pollution and restoration; monitoring of water resources; soil erosion and hydromorphological alterations. He has participated in more than 30 research projects. He is the coordinator of the National Monitoring Programme for the ecological water status of the Greek rivers, according to the EU Water Framework Directive. He is author or co-author of more than 95 articles in peer-reviewed scientific journals and he has been a member of the advisor committees of 5 Ph.D. and 26 M.Sc. students.

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Journal article
Published: 13 July 2021 in Atmosphere
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A hydrometeorological forecasting system has been operating at the Institute of Marine Biological Resources and Inland Waters (IMBRIW) of the Hellenic Centre for Marine Research (HCMR) since September 2015. The system consists of the Advanced Weather Research and Forecasting (WRF-ARW) model, the WRF-Hydro hydrological model, and the HEC-RAS hydraulic–hydrodynamic model. The system provides daily 120 h weather forecasts focusing on Greece (4 km horizontal resolution) and hydrological forecasts for the Spercheios and Evrotas rivers in Greece (100 m horizontal resolution), also providing flash flood inundation forecasts when needed (5 m horizontal resolution). The main aim of this study is to evaluate precipitation forecasts produced in a 4-year period (September 2015–August 2019) using measurements from meteorological stations across Greece. Water level forecasts for the Evrotas and Spercheios rivers were also evaluated using measurements from hydrological stations operated by the IMBRIW. Moreover, the forecast skill of the chained meteorological–hydrological–hydraulic operation of the system was investigated during a catastrophic flash flood in the Evrotas river. The results indicated that the system provided skillful precipitation and water level forecasts. The best evaluation results were yielded during rainy periods. They also demonstrated that timely flash flood forecasting products could benefit flood warning and emergency responses due to their efficiency and increased lead time.

ACS Style

George Varlas; Anastasios Papadopoulos; George Papaioannou; Elias Dimitriou. Evaluating the Forecast Skill of a Hydrometeorological Modelling System in Greece. Atmosphere 2021, 12, 902 .

AMA Style

George Varlas, Anastasios Papadopoulos, George Papaioannou, Elias Dimitriou. Evaluating the Forecast Skill of a Hydrometeorological Modelling System in Greece. Atmosphere. 2021; 12 (7):902.

Chicago/Turabian Style

George Varlas; Anastasios Papadopoulos; George Papaioannou; Elias Dimitriou. 2021. "Evaluating the Forecast Skill of a Hydrometeorological Modelling System in Greece." Atmosphere 12, no. 7: 902.

Journal article
Published: 08 July 2021 in Sensors
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The monitoring of the water stage in streams and rivers is essential for the sustainable management of water resources, particularly for the estimation of river discharges, the protection against floods and the design of hydraulic works. The Institute of Marine Biological Resources and Inland Waters of the Hellenic Centre for Marine Research (HCMR) has developed and operates automatic stations in rivers of Greece, which, apart from their monitoring role, offer opportunities for testing new monitoring equipment. This paper compares the performance of a new ultrasonic sensor, a non-contact water stage monitoring instrument, against a pressure transducer, both installed at the same location in an urban stream of the metropolitan area of Athens. The statistical and graph analysis of the almost one-year concurrent measurements from the two sensors revealed that stage differences never exceeded 7%, while the ultrasonic measurements were most of the time higher than the respective pressure transducer ones during the low flow conditions of the dry period and lower during the wet period of the year, when high flow events occurred. It is also remarkable that diurnal air temperature variations under stable hydrologic conditions had an impact on the measured stage from the ultrasonic sensor, which varied its stage measurements within a small but non-negligible range, while the pressure transducer did not practically fluctuate. Despite a slightly increased sensitivity of the ultrasonic sensor to meteorological conditions, the paper concludes that non-contact sensors for the monitoring of the water stage in rivers can be useful, especially where danger for possible damage of submersible instruments is increased.

ACS Style

Yiannis Panagopoulos; Anastasios Papadopoulos; Georgios Poulis; Emmanouil Nikiforakis; Elias Dimitriou. Assessment of an Ultrasonic Water Stage Monitoring Sensor Operating in an Urban Stream. Sensors 2021, 21, 4689 .

AMA Style

Yiannis Panagopoulos, Anastasios Papadopoulos, Georgios Poulis, Emmanouil Nikiforakis, Elias Dimitriou. Assessment of an Ultrasonic Water Stage Monitoring Sensor Operating in an Urban Stream. Sensors. 2021; 21 (14):4689.

Chicago/Turabian Style

Yiannis Panagopoulos; Anastasios Papadopoulos; Georgios Poulis; Emmanouil Nikiforakis; Elias Dimitriou. 2021. "Assessment of an Ultrasonic Water Stage Monitoring Sensor Operating in an Urban Stream." Sensors 21, no. 14: 4689.

Journal article
Published: 31 May 2021 in Hydrology
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Water resources, especially riverine ecosystems, are globally under qualitative and quantitative degradation due to human-imposed pressures. High-temporal-resolution data obtained from automatic stations can provide insights into the processes that link catchment hydrology and streamwater chemistry. The scope of this paper was to investigate the statistical behavior of high-frequency measurements at sites with known hydromorphological and pollution pressures. For this purpose, hourly time series of water levels and key water quality indicators (temperature, electric conductivity, and dissolved oxygen concentrations) collected from four automatic monitoring stations under different hydromorphological conditions and pollution pressures were statistically elaborated. Based on the results, the hydromorphological conditions and pollution pressures of each station were confirmed to be reflected in the results of the statistical analysis performed. It was proven that the comparative use of the statistics and patterns of the water level and quality high-frequency time series could be used in the interpretation of the current site status as well as allowing the detection of possible changes. This approach can be used as a tool for the definition of thresholds, and will contribute to the design of management and restoration measures for the most impacted areas.

ACS Style

Angeliki Mentzafou; George Varlas; Anastasios Papadopoulos; Georgios Poulis; Elias Dimitriou. Assessment of Automatically Monitored Water Levels and Water Quality Indicators in Rivers with Different Hydromorphological Conditions and Pollution Levels in Greece. Hydrology 2021, 8, 86 .

AMA Style

Angeliki Mentzafou, George Varlas, Anastasios Papadopoulos, Georgios Poulis, Elias Dimitriou. Assessment of Automatically Monitored Water Levels and Water Quality Indicators in Rivers with Different Hydromorphological Conditions and Pollution Levels in Greece. Hydrology. 2021; 8 (2):86.

Chicago/Turabian Style

Angeliki Mentzafou; George Varlas; Anastasios Papadopoulos; Georgios Poulis; Elias Dimitriou. 2021. "Assessment of Automatically Monitored Water Levels and Water Quality Indicators in Rivers with Different Hydromorphological Conditions and Pollution Levels in Greece." Hydrology 8, no. 2: 86.

Communication
Published: 11 May 2021 in Sustainability
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The present work provides the first records on microplastic (MP) amounts and types in rivers and wastewater effluents entering the Aegean Sea, eastern Mediterranean. Two rivers were sampled using a manta net (mesh size, 0.33 mm): a small urban and a medium-sized river with a rural, semiurban catchment. MPs in wastewater samples were collected at two wastewater treatment plants (WWTPs) within the Athens metropolitan area after secondary treatment and from a pilot biological membrane unit (MBR), using a series of sieves. MPs in the samples were identified using stereoscopic image analysis and spectroscopic techniques. MP concentrations in the rivers were found to be variable, with as high as 27.73 items m−3 in the urban river. Differences in MP shape types, sizes, and polymer types reflect catchment size and usage. MP concentration in wastewater effluents was found to be 100 times higher in the secondary treatment (213 items m−3) than that in the pilot MBR (2.29 items m−3), with filaments and polymers indicative of synthetic textiles and household use. Further research is needed in order to accurately determine variability in MP concentrations and fluxes from these two pathways in the eastern Mediterranean Sea and elucidate the role of rivers in MP retention.

ACS Style

Christina Zeri; Argyro Adamopoulou; Angeliki Koi; Nicholas Koutsikos; Efthymios Lytras; Elias Dimitriou. Rivers and Wastewater-Treatment Plants as Microplastic Pathways to Eastern Mediterranean Waters: First Records for the Aegean Sea, Greece. Sustainability 2021, 13, 5328 .

AMA Style

Christina Zeri, Argyro Adamopoulou, Angeliki Koi, Nicholas Koutsikos, Efthymios Lytras, Elias Dimitriou. Rivers and Wastewater-Treatment Plants as Microplastic Pathways to Eastern Mediterranean Waters: First Records for the Aegean Sea, Greece. Sustainability. 2021; 13 (10):5328.

Chicago/Turabian Style

Christina Zeri; Argyro Adamopoulou; Angeliki Koi; Nicholas Koutsikos; Efthymios Lytras; Elias Dimitriou. 2021. "Rivers and Wastewater-Treatment Plants as Microplastic Pathways to Eastern Mediterranean Waters: First Records for the Aegean Sea, Greece." Sustainability 13, no. 10: 5328.

Journal article
Published: 08 April 2021 in Sustainability
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Among the Sustainable Development Goals (SDGs) established in the 2030 Agenda, goals 6.3, regarding clean water and improve of water quality, and 6.5, regarding integrated water resources management, highlight the need for the implementation of successful environmental water quality monitoring programs of transboundary river waterbodies. In the present study, the designation of high priority areas for water quality monitoring of Drin transboundary watershed is performed using a suitability model, a GIS-based multicriteria decision analysis (GIS-MCDA) approach that takes into consideration the most important conditioning factors that impose pressures on rivers. Based on the results, the methodological approach used manages to sufficiently delimit the areas with increased need for water quality monitoring in the Drin watershed, and the validation procedure produces a correlation coefficient of 0.454 (statistically significant at a 0.01 level). Limitations arise in the case of a lack of detailed information or inaccurate input data and due to the inconsistency among the input data and the different methodological approaches regarding the information collection of each country involved. These restrictions foreground the need for cooperation between the countries involved regarding the exchange of scientific knowledge and common legislation, so as to achieve integrated, effective, and sustainable management of water resources of the area.

ACS Style

Angeliki Mentzafou; Momčilo Blagojević; Elias Dimitriou. A GIS-MCDA-Based Suitability Analysis for Meeting Targets 6.3 and 6.5 of the Sustainable Development Goals. Sustainability 2021, 13, 4153 .

AMA Style

Angeliki Mentzafou, Momčilo Blagojević, Elias Dimitriou. A GIS-MCDA-Based Suitability Analysis for Meeting Targets 6.3 and 6.5 of the Sustainable Development Goals. Sustainability. 2021; 13 (8):4153.

Chicago/Turabian Style

Angeliki Mentzafou; Momčilo Blagojević; Elias Dimitriou. 2021. "A GIS-MCDA-Based Suitability Analysis for Meeting Targets 6.3 and 6.5 of the Sustainable Development Goals." Sustainability 13, no. 8: 4153.

Journal article
Published: 01 April 2021 in Sustainability
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Nature-based solutions (NBS) are being deployed around the world in order to address hydrometeorological hazards, including flooding, droughts, landslides and many others. The term refers to techniques inspired, supported and copied from nature, avoiding large constructions and other harmful interventions. In this work the development and evaluation of an NBS applied to the Spercheios river basin in Central Greece is presented. The river is susceptible to heavy rainfall and bank overflow, therefore the intervention selected is a natural water retention measure that aims to moderate the impact of flooding and drought in the area. After the deployment of the NBS, we examine the benefits under current and future climate conditions, using various climate change scenarios. Even though the NBS deployed is small compared to the rest of the river, its presence leads to a decrease in the maximum depth of flooding, maximum velocity and smaller flooded areas. Regarding the subsurface/groundwater storage under current and future climate change and weather conditions, the NBS construction seems to favor long-term groundwater recharge.

ACS Style

Christos Spyrou; Michael Loupis; Νikos Charizopoulos; Ilektra Apostolidou; Angeliki Mentzafou; George Varlas; Anastasios Papadopoulos; Elias Dimitriou; Depy Panga; Lamprini Gkeka; Paul Bowyer; Susanne Pfeifer; Sisay Debele; Prashant Kumar. Evaluating Nature-Based Solution for Flood Reduction in Spercheios River Basin under Current and Future Climate Conditions. Sustainability 2021, 13, 3885 .

AMA Style

Christos Spyrou, Michael Loupis, Νikos Charizopoulos, Ilektra Apostolidou, Angeliki Mentzafou, George Varlas, Anastasios Papadopoulos, Elias Dimitriou, Depy Panga, Lamprini Gkeka, Paul Bowyer, Susanne Pfeifer, Sisay Debele, Prashant Kumar. Evaluating Nature-Based Solution for Flood Reduction in Spercheios River Basin under Current and Future Climate Conditions. Sustainability. 2021; 13 (7):3885.

Chicago/Turabian Style

Christos Spyrou; Michael Loupis; Νikos Charizopoulos; Ilektra Apostolidou; Angeliki Mentzafou; George Varlas; Anastasios Papadopoulos; Elias Dimitriou; Depy Panga; Lamprini Gkeka; Paul Bowyer; Susanne Pfeifer; Sisay Debele; Prashant Kumar. 2021. "Evaluating Nature-Based Solution for Flood Reduction in Spercheios River Basin under Current and Future Climate Conditions." Sustainability 13, no. 7: 3885.

Special issue paper
Published: 29 March 2021 in Hydrological Processes
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A common source of uncertainty in flood inundation forecasting is the hydrograph used. Given the role of sea‐air‐hydro‐land chain processes on the water cycle, flood hydrographs in coastal areas can be indirectly affected by sea state. This study investigates sea‐state effects on precipitation, discharge, and flood inundation forecasting implementing atmospheric, ocean wave, hydrological, and hydraulic‐hydrodynamic coupled models. The Chemical Hydrological Atmospheric Ocean wave System (CHAOS) was used for coupled hydro‐meteorological‐wave simulations “accounting” or “not accounting” the impact of sea state on precipitation and, subsequently, on flood hydrograph. CHAOS includes the WRF‐Hydro hydrological model and the WRF‐ARW meteorological model two‐way coupled with the WAM wave model through the OASIS3‐MCT coupler. Subsequently, the 2D HEC‐RAS hydraulic‐hydrodynamic model was forced by the flood hydrographs and map the inundated areas. A flash flood event occurred on 15 November 2017 in Mandra, Attica, Greece, causing 24 fatalities, and damages was selected as case study. The calibration of models was performed exploiting historical flood records and previous studies. Human interventions such as hydraulic works and the urban areas were included in the hydraulic modeling geometry domain. The representation of the resistance caused by buildings was based on Unmanned Aerial System (UAS) data while the local elevation rise method was used in the urban‐flood simulation. The flood extent results were assessed using the Critical Success Index (CSI), and CSI penalize. Integrating sea‐state affected the forecast of precipitation and discharge peaks, causing up to +24% and from ‐8% to +36% differences, respectively, improving inundation forecast by 4.5% and flooding additional ~70 building blocks. The precipitation forcing time step was also highlighted as significant factor in such a small‐scale flash flood. The integrated multidisciplinary methodological approach could be adopted in operational forecasting for civil protection applications facilitating the protection of socio‐economic activities and human lives during similar future events.

ACS Style

George Papaioannou; George Varlas; Anastasios Papadopoulos; Athanasios Loukas; Petros Katsafados; Elias Dimitriou. Investigating sea‐state effects on flash flood hydrograph and inundation forecasting. Hydrological Processes 2021, 35, 1 .

AMA Style

George Papaioannou, George Varlas, Anastasios Papadopoulos, Athanasios Loukas, Petros Katsafados, Elias Dimitriou. Investigating sea‐state effects on flash flood hydrograph and inundation forecasting. Hydrological Processes. 2021; 35 (4):1.

Chicago/Turabian Style

George Papaioannou; George Varlas; Anastasios Papadopoulos; Athanasios Loukas; Petros Katsafados; Elias Dimitriou. 2021. "Investigating sea‐state effects on flash flood hydrograph and inundation forecasting." Hydrological Processes 35, no. 4: 1.

Journal article
Published: 23 March 2021 in Hydrology
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Riparian zones play an important role in the ecological stability of rivers. In particular, the quality of the riparian vegetation is a significant component of the hydromorphological status. In Europe, the QBR index (Qualitat del Bosc de Ribera) and the River Habitat Survey (RHS) are commonly used for the qualitative assessment of the riparian vegetation. In this study, we estimated the QBR index and the Riparian Quality index, which is derived from the RHS method, for 123 river reaches of the National Monitoring Network of Greece. Our field work included the completion of RHS and QBR protocols, as well as the use of Unmanned Aerial Vehicles (UAVs). The aim of this study is to assess the riparian vegetation status and to identify linkages with the dominant land uses within the catchment. Correlation analysis was used to identify the relationships between hydromorphological alterations and the degradation of the riparian vegetation, as well as their connection to land uses in the catchment area. Our results highlighted severe modifications of the riparian vegetation for the majority of the studied reaches. We also showed a differentiation of the QBR with respect to changes in the altitude and the land uses in the catchment area. Overall QBR reflects the variation in the riparian vegetation quality better than RQI. Our findings constitute an assessment of the status of the riparian zones in Greek rivers and set the basis for further research for the development of new and effective tools for a rapid quality assessment of the riparian zones.

ACS Style

Anna Latsiou; Theodora Kouvarda; Konstantinos Stefanidis; George Papaioannou; Konstantinos Gritzalis; Elias Dimitriou. Pressures and Status of the Riparian Vegetation in Greek Rivers: Overview and Preliminary Assessment. Hydrology 2021, 8, 55 .

AMA Style

Anna Latsiou, Theodora Kouvarda, Konstantinos Stefanidis, George Papaioannou, Konstantinos Gritzalis, Elias Dimitriou. Pressures and Status of the Riparian Vegetation in Greek Rivers: Overview and Preliminary Assessment. Hydrology. 2021; 8 (1):55.

Chicago/Turabian Style

Anna Latsiou; Theodora Kouvarda; Konstantinos Stefanidis; George Papaioannou; Konstantinos Gritzalis; Elias Dimitriou. 2021. "Pressures and Status of the Riparian Vegetation in Greek Rivers: Overview and Preliminary Assessment." Hydrology 8, no. 1: 55.

Journal article
Published: 15 March 2021 in Water Research
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Understanding the climatic drivers of eutrophication is critical for lake management under the prism of the global change. Yet the complex interplay between climatic variables and lake processes makes prediction of phytoplankton biomass a rather difficult task. Quantifying the relative influence of climate-related variables on the regulation of phytoplankton biomass requires modelling approaches that use extensive field measurements paired with accurate meteorological observations. In this study we used climate and lake related variables obtained from the ERA5-Land reanalysis dataset combined with a large dataset of in-situ measurements of chlorophyll-a and phytoplankton biomass from 50 water bodies to develop models of phytoplankton related responses as functions of the climate reanalysis data. We used chlorophyll-a and phytoplankton biomass as response metrics of phytoplankton growth and we employed two different modelling techniques, boosted regression trees (BRT) and generalized additive models for location scale and shape (GAMLSS). According to our results, the fitted models had a relatively high explanatory power and predictive performance. Boosted regression trees had a high pseudo R2 with the type of the lake, the total layer temperature, and the mix-layer depth being the three predictors with the higher relative influence. The best GAMLSS model retained mix-layer depth, mix-layer temperature, total layer temperature, total runoff and 10-m wind speed as significant predictors (p<0.001). Regarding the phytoplankton biomass both modelling approaches had less explanatory power than those for chlorophyll-a. Concerning the predictive performance of the models both the BRT and GAMLSS models for chlorophyll-a outperformed those for phytoplankton biomass. Overall, we consider these findings promising for future limnological studies as they bring forth new perspectives in modelling ecosystem responses to a wide range of climate and lake variables. As a concluding remark, climate reanalysis can be an extremely useful asset for lake research and management.

ACS Style

Konstantinos Stefanidis; George Varlas; Aikaterini Vourka; Anastasios Papadopoulos; Elias Dimitriou. Delineating the relative contribution of climate related variables to chlorophyll-a and phytoplankton biomass in lakes using the ERA5-Land climate reanalysis data. Water Research 2021, 196, 117053 .

AMA Style

Konstantinos Stefanidis, George Varlas, Aikaterini Vourka, Anastasios Papadopoulos, Elias Dimitriou. Delineating the relative contribution of climate related variables to chlorophyll-a and phytoplankton biomass in lakes using the ERA5-Land climate reanalysis data. Water Research. 2021; 196 ():117053.

Chicago/Turabian Style

Konstantinos Stefanidis; George Varlas; Aikaterini Vourka; Anastasios Papadopoulos; Elias Dimitriou. 2021. "Delineating the relative contribution of climate related variables to chlorophyll-a and phytoplankton biomass in lakes using the ERA5-Land climate reanalysis data." Water Research 196, no. : 117053.

Preprint content
Published: 04 March 2021
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Good water quality status in rivers and lakes is vital for both human well-being and biodiversity conservation and requires efficient monitoring and restoration strategies. This is reflected in an increasing number of International and National legislations which enforce water resources management and monitoring at a basin scale.

For this purpose, state-of-the-art monitoring schemes have been developed by using low-cost, technologically advanced sensors and Internet of Things (IoT) infrastructure. Remote sensing offers also a good water monitoring alternative but is more appropriate for medium to large water bodies with less dynamic character in comparison to small scale, temporary rivers.

Recent technological advances in sensors technology, energy supply, telecommunication protocols and data handling, facilitate the use of automated monitoring stations, but still, deployment of extended networks with readily available data remains far from common practice. Installation and operational costs for the development of such monitoring networks are among the most commonly faced challenges.

The main aim of this effort is to present the development of a network of automatic monitoring stations that measure in near real time water level and physicochemical parameters in several Greek rivers. This infrastructure has been developed under the project “Open ELIoT” (Open Internet of Things infrastructure for online environmental services - https://www.openeliot.com/en/), which was funded by the Greek National Structural Funds. It includes a low cost and easy to produce hardware node, coupled with commercial sensors of industrial specifications, as well as an IoT data platform, elaborating and presenting data, based on open technologies.

During its initial operation phase, the system has been deployed in sites with different hydrological regimes and various pressures to water quality, including (a) an urban Mediterranean stream (Pikrodafni stream), and (b) the urban part of a continental river running through an agricultural area (Lithaios stream).

Preliminary data on the continuous monitoring of sites (a) and (b) are presented here, reflecting the differences in pressures to the respective water bodies. Pikrodafni stream which is located close to the center of Athens – Greece and receives a lot of pressure from urban waste, illustrates Dissolved Oxygen (DO) concentration with a heavily skewed distribution towards low values (mean value: 2.15 mg/l and median: 0.93 mg/l). On the contrary, in Lithaios stream, which is more affected by agricultural runoff, dissolved oxygen data approach a normal distribution (mean value: 6.93 mg/l and median: 7.03 mg/l). The 25th and 75th percentiles in Pikrodafni stream are: 0.1 mg/l and 3.47 mg/l respectively while in Lithaios stream are: 5.6 mg/l and 8.45 mg/l. The average water temperature is similar to both streams (18.8 oC in Pikrodafni and 16.2 oC in Lithaios). Therefore, the significant differences in DO concentrations between the two streams indicate the need for continuous monitoring of data that facilitates the identification of pressures and enables stakeholders to respond to pollution events in time.

ACS Style

Elias Dimitriou; Georgios Poulis; Anastasios Papadopoulos. Development of a water monitoring network based on open architecture and Internet-of-Things technologies. 2021, 1 .

AMA Style

Elias Dimitriou, Georgios Poulis, Anastasios Papadopoulos. Development of a water monitoring network based on open architecture and Internet-of-Things technologies. . 2021; ():1.

Chicago/Turabian Style

Elias Dimitriou; Georgios Poulis; Anastasios Papadopoulos. 2021. "Development of a water monitoring network based on open architecture and Internet-of-Things technologies." , no. : 1.

Technical note
Published: 20 February 2021 in Hydrology
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The monitoring of surface waters is of fundamental importance for their preservation under good quantitative and qualitative conditions, as it can facilitate the understanding of the actual status of water and indicate suitable management actions. Taking advantage of the experience gained from the coordination of the national water monitoring program in Greece and the available funding from two ongoing infrastructure projects, the Institute of Inland Waters of the Hellenic Centre for Marine Research has developed the first homogeneous real-time network of automatic water monitoring across many Greek rivers. In this paper, its installation and maintenance procedures are presented with emphasis on the data quality checks, based on values range and variability tests, before their online publication and dissemination to end-users. Preliminary analyses revealed that the water pH and dissolved oxygen (DO) sensors and produced data need increased maintenance and quality checks respectively, compared to the more reliably recorded water stage, temperature (T) and electrical conductivity (EC). Moreover, the data dissemination platform and selected data visualization options are demonstrated and the need for both this platform and the monitoring network to be maintained and potentially expanded after the termination of the funding projects is highlighted.

ACS Style

Yiannis Panagopoulos; Anna Konstantinidou; Konstantinos Lazogiannis; Anastasios Papadopoulos; Elias Dimitriou. A New Automatic Monitoring Network of Surface Waters in Greece: Preliminary Data Quality Checks and Visualization. Hydrology 2021, 8, 33 .

AMA Style

Yiannis Panagopoulos, Anna Konstantinidou, Konstantinos Lazogiannis, Anastasios Papadopoulos, Elias Dimitriou. A New Automatic Monitoring Network of Surface Waters in Greece: Preliminary Data Quality Checks and Visualization. Hydrology. 2021; 8 (1):33.

Chicago/Turabian Style

Yiannis Panagopoulos; Anna Konstantinidou; Konstantinos Lazogiannis; Anastasios Papadopoulos; Elias Dimitriou. 2021. "A New Automatic Monitoring Network of Surface Waters in Greece: Preliminary Data Quality Checks and Visualization." Hydrology 8, no. 1: 33.

Review
Published: 12 February 2021 in Water
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The European Water Framework Directive 2000/60/EC (WFD) has been implemented over the past 20 years, using physicochemical, biological and hydromorphological elements to assess the ecological status of surface waters. Benthic diatoms (i.e., phytobenthos) are one of the most common biological quality elements (BQEs) used in surface water monitoring and are particularly successful in detecting eutrophication, organic pollution and acidification. Herein, we reviewed their implementation in river biomonitoring for the purposes of the WFD, highlighting their advantages and disadvantages over other BQEs, and we discuss recent advances that could be applied in future biomonitoring. Until now, phytobenthos have been intercalibrated by the vast majority (26 out of 28) of EU Member States (MS) in 54% of the total water bodies assessed and was the most commonly used BQE after benthic invertebrates (85% of water bodies), followed by fish (53%), macrophytes (27%) and phytoplankton (4%). To meet the WFD demands, numerous taxonomy-based quality indices have been developed among MS, presenting, however, uncertainties possibly related to species biogeography. Recent development of different types of quality indices (trait-based, DNA sequencing and predictive modeling) could provide more accurate results in biomonitoring, but should be validated and intercalibrated among MS before their wide application in water quality assessments.

ACS Style

Andreas Masouras; Ioannis Karaouzas; Elias Dimitriou; George Tsirtsis; Evangelia Smeti. Benthic Diatoms in River Biomonitoring—Present and Future Perspectives within the Water Framework Directive. Water 2021, 13, 478 .

AMA Style

Andreas Masouras, Ioannis Karaouzas, Elias Dimitriou, George Tsirtsis, Evangelia Smeti. Benthic Diatoms in River Biomonitoring—Present and Future Perspectives within the Water Framework Directive. Water. 2021; 13 (4):478.

Chicago/Turabian Style

Andreas Masouras; Ioannis Karaouzas; Elias Dimitriou; George Tsirtsis; Evangelia Smeti. 2021. "Benthic Diatoms in River Biomonitoring—Present and Future Perspectives within the Water Framework Directive." Water 13, no. 4: 478.

Journal article
Published: 10 January 2021 in Hydrology
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River flow alterations, caused by climate variability/change and intense anthropogenic uses (e.g., flow regulation by dams) are considered among the main global challenges of which hydrologists should be dealing with. For the purpose of this study, environmental flow and potential hydrological alterations are made for the extended Drin river basin, with limited historical hydrological information available. To overcome this limitation environmental flow assessment is made using simulated streamflow data from a watershed hydrological model. Descriptive statistics applied to streamflow values indicate that median monthly flows with no anthropogenic uses are consistently greater than those with anthropogenic uses by 0–37.4 m3/s in all subbasins. Moreover, an investigation of potential climate variability/change impact on river flow regime is made using streamflow simulations from a global hydrological model. Results indicate that hydrologic alteration is intense between nonregulated and regulated streamflow conditions. More specifically, for all Global Circulation Models and Regional Climate Models combinations, and both regulated and unregulated streamflow conditions, the minimum discharge values had statistically significant decreasing trends, except one combination (RCP 4.5–RCA4/ECEARTH) for unregulated conditions. Finally, results from this preliminary analysis could enhance the necessary conversations among all relevant stakeholders to discuss and decide on sustainable water resources management issues for the development of a Drin Basin Management Plan in the future.

ACS Style

Christina Papadaki; Elias Dimitriou. River Flow Alterations Caused by Intense Anthropogenic Uses and Future Climate Variability Implications in the Balkans. Hydrology 2021, 8, 7 .

AMA Style

Christina Papadaki, Elias Dimitriou. River Flow Alterations Caused by Intense Anthropogenic Uses and Future Climate Variability Implications in the Balkans. Hydrology. 2021; 8 (1):7.

Chicago/Turabian Style

Christina Papadaki; Elias Dimitriou. 2021. "River Flow Alterations Caused by Intense Anthropogenic Uses and Future Climate Variability Implications in the Balkans." Hydrology 8, no. 1: 7.

Journal article
Published: 08 October 2020 in Ecological Engineering
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Fishway research has long focused on post-establishment assessments to optimize fish passage efficiency. Model-based optimization with the use of hydrodynamic-habitat models (HHMs) has rarely been employed to investigate passage suitability based on key hydraulic variables. In this study, a vertical slot fishway was designed, the hydraulic properties of twelve types that varied by slope, slot width and pool size were simulated using a two-dimensional HHM, and the suitability of macroinvertebrates and of seven fish groups, encompassing various guilds and size classes, was assessed for each fishway type at seven discharge scenarios, ranging from 0.1 m3/s to 1.3 m3/s. Suitability was primarily influenced by water depth. At optimal depths, suitability was fine-tuned by flow velocity to different optima per biotic group based on fixed interplays between discharge, slope and slot width: water depths were higher at high discharges, low slopes and narrow slots; flow velocities were higher at high discharges, high slopes and wide slots. Our ecologically optimal, multispecies, vertical slot fishway, had 5% slope and 30-cm wide slots, with discharges shifting between 0.15 m3/s and 0.6 m3/s to balance the needs of all species and life stages studied. Yet, even this optimal fishway could not guarantee 100% suitability for all species. The overall suitability was moderate (approx. 50–60%), higher at the pools and lower at the slots, and critically influenced by the type of substrate. We conclude that technical fishways cannot be simultaneously ideal for all species and life stages of a river reach/basin, due to the often-contrasting habitat preferences that need to be adapted to fixed interplays of hydraulic conditions. Within these limitations, however, model-based ecological pre-optimization is crucial for optimizing and deploying fishways that will guarantee suitable passage routes for a wide range of species and life stages, ultimately restoring the hydromorphological and ecological connectivity of dammed rivers.

ACS Style

George Mitsopoulos; Christos Theodoropoulos; Christina Papadaki; Elias Dimitriou; José Maria Santos; Stamatis Zogaris; Anastasios Stamou. Model-based ecological optimization of vertical slot fishways using macroinvertebrates and multispecies fish indicators. Ecological Engineering 2020, 158, 106081 .

AMA Style

George Mitsopoulos, Christos Theodoropoulos, Christina Papadaki, Elias Dimitriou, José Maria Santos, Stamatis Zogaris, Anastasios Stamou. Model-based ecological optimization of vertical slot fishways using macroinvertebrates and multispecies fish indicators. Ecological Engineering. 2020; 158 ():106081.

Chicago/Turabian Style

George Mitsopoulos; Christos Theodoropoulos; Christina Papadaki; Elias Dimitriou; José Maria Santos; Stamatis Zogaris; Anastasios Stamou. 2020. "Model-based ecological optimization of vertical slot fishways using macroinvertebrates and multispecies fish indicators." Ecological Engineering 158, no. : 106081.

Case report
Published: 20 August 2020 in Sustainability
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This study demonstrates a new nature-based solution (NBS) project in agriculture, the ‘Karla’ reservoir in Central Greece, a unique example at European scale, of a lake ecosystem which was dried and is now restored with the purpose to maximize the efficiency of water provision in agriculture and biodiversity enhancement. In this article, we present: (a) The historical developments from the existence of the old natural Lake Karla until the reconstruction of the homonymous artificial reservoir, (b) the environmental and economic benefits that the new project delivers, and (c) the governance and management mechanisms that can ensure the efficient operation of the project. The analysis shows that the reconstructed Lake Karla can serve as a multi-purpose project to combat water scarcity, achieving a twofold crop yield production and respective agricultural income in the surrounding area, securing the coverage of the water supply needs of the closest city, improving the status of groundwater resources, developing a natural shelter for biodiversity and emerging recreation and touristic opportunities. At the same time, its construction and operation costs can be recovered, and the proposed governance plan can ensure the viability of the whole project inspiring similar multi-purpose water retention projects for investment in agriculture and the environment in southern Europe but also in other water scarce regions.

ACS Style

Yiannis Panagopoulos; Elias Dimitriou. A Large-Scale Nature-Based Solution in Agriculture for Sustainable Water Management: The Lake Karla Case. Sustainability 2020, 12, 6761 .

AMA Style

Yiannis Panagopoulos, Elias Dimitriou. A Large-Scale Nature-Based Solution in Agriculture for Sustainable Water Management: The Lake Karla Case. Sustainability. 2020; 12 (17):6761.

Chicago/Turabian Style

Yiannis Panagopoulos; Elias Dimitriou. 2020. "A Large-Scale Nature-Based Solution in Agriculture for Sustainable Water Management: The Lake Karla Case." Sustainability 12, no. 17: 6761.

Original article
Published: 26 July 2020 in Environmental Processes
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Hydrological variability is of great importance for water resources management. Regardless of how rivers are individually managed, numerous research studies have concluded that aquatic organisms are highly dependent on flow regime variability. Nevertheless, natural streamflow regimes are being altered due to human-induced pressures and climate change/variability, and sufficient biological information in not incorporated in efforts to minimize these effects. Thus, there is an urgent need to develop sustainable environmental flow management guidelines to manage the risk associated with alterations to the flow regime particularly in areas where flow-ecology relationships have not been well studied. This study focuses on a stream with high natural flow regime variability, typical in Mediterranean countries. The major finding of this work is that the estimated Suitable Range of Discharges (SRD) could better address environmental water requirements, rather than simply allocating single value minimum ecological flows. SRD was estimated using advocate statistical analysis of hydrological data series, coupled with habitat suitability models to balance the trade-offs between natural flow variability and human water needs. Combination of the aforementioned approaches was made using the West Balkan trout as a biological component which is a very important species for the quantification of environmental flows. Overall implementation of SRD during dry season is likely to provide large habitat areas for 58 to 67% of the time for the small-size fish and 35 to 55% of the time for the large-size West Balkan trout, according to the Weighted Usable Area0.5 threshold index.

ACS Style

Christina Papadaki; Konstantinos Soulis; Vasilis Bellos; Lazaros Ntoanidis; Elias Dimitriou. Estimation of a Suitable Range of Discharges for the Development of Instream Flow Recommendations. Environmental Processes 2020, 7, 703 -721.

AMA Style

Christina Papadaki, Konstantinos Soulis, Vasilis Bellos, Lazaros Ntoanidis, Elias Dimitriou. Estimation of a Suitable Range of Discharges for the Development of Instream Flow Recommendations. Environmental Processes. 2020; 7 (3):703-721.

Chicago/Turabian Style

Christina Papadaki; Konstantinos Soulis; Vasilis Bellos; Lazaros Ntoanidis; Elias Dimitriou. 2020. "Estimation of a Suitable Range of Discharges for the Development of Instream Flow Recommendations." Environmental Processes 7, no. 3: 703-721.

Journal article
Published: 29 June 2020 in Remote Sensing
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Assessing chlorophyll-a (Chl-a) pigments in complex inland water systems is of key importance as this parameter constitutes a major ecosystem integrity indicator. In this study, a methodological framework is proposed for quantifying Chl-a pigments using Earth observation (EO) data from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and 8 Operational Land Imager (OLI) sensors. The first step of the methodology involves the implementation of stepwise multiple regression (MLR) analysis of the available Chl-a dataset. Then, principal component analysis (PCA) is performed to explore Greek lakes’ potential interrelationships based on their Chl-a values in conjunction with certain criteria: their characteristics (artificial/natural), typology, and climatic type. Additionally, parameters such as seasonal water sampling and the date difference between sampling and satellite overpass are taken into consideration. Next, is implemented a stepwise multiple regression analysis among different groups of cases, formed by the criteria indicated from the PCA itself. This effort aimed at exploring different remote sensing-derived Chl-a algorithms for various types of lakes. The practical use of the proposed approach was evaluated in a total of 50 lake water bodies (natural and artificial) from 2013–2018, constituting the National Lake Network Monitoring of Greece in the context of the Water Framework Directive (WFD). All in all, the results evidenced the suitability of Landsat data when used with the proposed technique to estimate log-transformed Chl-a. The proposed scheme resulted in the development of models separately for natural (R = 0.78; RMSE = 1.3 μg/L) and artificial lakes (R = 0.76; RMSE = 1.29 μg/L), while the model developed without criteria proved weaker (R = 0.65; RMSE = 1.85 μg/L) in comparison to the other ones examined. The methodological framework proposed herein can be used as a useful resource toward a continuous monitoring and assessment of lake water quality, supporting sustainable water resources management.

ACS Style

Vassiliki Markogianni; Dionissios Kalivas; George P. Petropoulos; Elias Dimitriou. Estimating Chlorophyll-a of Inland Water Bodies in Greece Based on Landsat Data. Remote Sensing 2020, 12, 2087 .

AMA Style

Vassiliki Markogianni, Dionissios Kalivas, George P. Petropoulos, Elias Dimitriou. Estimating Chlorophyll-a of Inland Water Bodies in Greece Based on Landsat Data. Remote Sensing. 2020; 12 (13):2087.

Chicago/Turabian Style

Vassiliki Markogianni; Dionissios Kalivas; George P. Petropoulos; Elias Dimitriou. 2020. "Estimating Chlorophyll-a of Inland Water Bodies in Greece Based on Landsat Data." Remote Sensing 12, no. 13: 2087.

Journal article
Published: 27 May 2020 in Water
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Reduction of nutrient loadings is often prioritized among other management measures for improving the water quality of freshwaters within the catchment. However, urban point sources and agriculture still thrive as the main drivers of nitrogen and phosphorus pollution in European rivers. With this article we present a nationwide assessment of nitrogen and phosphorus loads that 18 large rivers in Greece receive with the purpose to assess variability among seasons, catchments, and river types and distinguish relationships between loads and land uses of the catchment. We employed an extensive dataset of 636 field measurements of nutrient concentrations and river discharges to calculate nitrogen and phosphorus loads. Descriptive statistics and a cluster analysis were conducted to identify commonalties and differences among catchments and seasons. In addition a network analysis was conducted and its modularity feature was used to detect commonalities among rivers and sampling sites with regard to their nutrient loads. A correlation analysis was used to identify major possible connections between types of land uses and nutrient loads. The results indicated that the rivers Alfeios, Strymonas, and Aliakmonas receive the highest inorganic nitrogen loads while the highest inorganic phosphorus loads were calculated for the rivers Strymonas, Aliakmonas, and Axios. Concerning the temporal variation of loads, inorganic nitrogen presented a peak on March and gradually declined until October when the dry period typically ends for most regions of Greece. Inorganic phosphorus loads had the highest average value in August and the lowest in October. Thus, our findings confirmed the presence of a typical seasonal variation in nitrogen loads that follows the seasonality in hydrology where high surface runoff during the wet months contribute to higher river discharges and higher nitrogen loads from the catchment. On the contrary, high phosphorus loads persisted during dry months that could be attributed to a dilution effect. Furthermore, the results imply a clear connection between agriculture and both nitrogen and phosphorus. Overall, this work presents extensive information on the nitrogen and phosphorus loads that major rivers in Greece receive that can largely aid water managers to adapt and revise basin management plans in accordance with agricultural management (e.g., which months farmers should reduce the use of fertilizers) with the purpose of meeting the environmental targets defined by the Water Framework Directive (WFD).

ACS Style

Konstantinos Stefanidis; Aikaterini Christopoulou; Serafeim Poulos; Emmanouil Dassenakis; Elias Dimitriou. Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive. Water 2020, 12, 1531 .

AMA Style

Konstantinos Stefanidis, Aikaterini Christopoulou, Serafeim Poulos, Emmanouil Dassenakis, Elias Dimitriou. Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive. Water. 2020; 12 (6):1531.

Chicago/Turabian Style

Konstantinos Stefanidis; Aikaterini Christopoulou; Serafeim Poulos; Emmanouil Dassenakis; Elias Dimitriou. 2020. "Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive." Water 12, no. 6: 1531.

Journal article
Published: 08 April 2020 in Hydrology
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The Water Framework Directive (WFD) requires from member states to monitor hydromorphological features of rivers in order to assess their ecological quality. Thus, numerous hydromorphological assessment methods have been developed with most of them focusing on the dynamics of hydrology, geomorphology and riparian zone extent. Within the scope of this study, we assessed the hydromorphological features of 106 river reaches distributed among thirteen WFD River Basin Districts (RBDs) to identify the main drivers of hydromorphological perturbation at a national scale. The studied reaches reflect a wide range of natural variability as they include various types of watercourses extending from lowlands to mid-altitude and mountainous systems. We employed the River Habitat Survey (RHS), and we recorded hydromorphological features and modifications in both banks and the channel bed along 500 m for each reach. Then, the Habitat Modification Score (HMS) and the individual sub-scores that indicate the extent of specific modifications (e.g., bridges, fords, weirs, bank reprofiling, bank reinforcement, etc.) were calculated in order to a) assess the severity of the total artificial modification and b) to highlight the most common and severe causes of overall alteration. The results showed that alterations such as reprofiling and reinforcement of banks contributed the most to the total HMS followed by the presence of fords and bridges. Particularly, the bank alterations indicate a serious deterioration of the longitudinal profile of the reaches, while the occurrence of many fords and bridges is the main cause for perturbations that affect locally the stream cross-sectional profile. Overall, these results compile a first nationwide assessment of the hydromorphological status of Greek rivers in line with the WFD and set the basis for further research that will focus on the diversity of stream habitat features as a measure for the overall ecological quality.

ACS Style

Konstantinos Stefanidis; Anna Latsiou; Theodora Kouvarda; Anastasia Lampou; Nektarios Kalaitzakis; Konstantinos Gritzalis; Elias Dimitriou. Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece. Hydrology 2020, 7, 22 .

AMA Style

Konstantinos Stefanidis, Anna Latsiou, Theodora Kouvarda, Anastasia Lampou, Nektarios Kalaitzakis, Konstantinos Gritzalis, Elias Dimitriou. Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece. Hydrology. 2020; 7 (2):22.

Chicago/Turabian Style

Konstantinos Stefanidis; Anna Latsiou; Theodora Kouvarda; Anastasia Lampou; Nektarios Kalaitzakis; Konstantinos Gritzalis; Elias Dimitriou. 2020. "Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece." Hydrology 7, no. 2: 22.

Journal article
Published: 01 February 2020 in Journal of Ecological Engineering
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Urbanization of stream ecosystems with the purpose of managing flash-flood events is considered nowadays responsible for habitat loss and alteration of the natural flow regime with severe implications for the ecosystem functioning. Not surprisingly river scientists have started seeking...

ACS Style

Olga Ourloglou; Konstantinos Stefanidis; Elias Dimitriou. Assessing Nature-Based and Cassical Engineering Solutions for Flood-Risk Reduction in Urban Streams. Journal of Ecological Engineering 2020, 21, 46 -56.

AMA Style

Olga Ourloglou, Konstantinos Stefanidis, Elias Dimitriou. Assessing Nature-Based and Cassical Engineering Solutions for Flood-Risk Reduction in Urban Streams. Journal of Ecological Engineering. 2020; 21 (2):46-56.

Chicago/Turabian Style

Olga Ourloglou; Konstantinos Stefanidis; Elias Dimitriou. 2020. "Assessing Nature-Based and Cassical Engineering Solutions for Flood-Risk Reduction in Urban Streams." Journal of Ecological Engineering 21, no. 2: 46-56.