Evangelos Baltas - Academia.edu (original) (raw)

Papers by Evangelos Baltas

Environmental sciences proceedings, Aug 18, 2020

The current analysis attempts to quantify the interlinkages between the water, energy and food se... more The current analysis attempts to quantify the interlinkages between the water, energy and food sectors of California covering the period 2002-2015. The results reveal that 25% (60,696 GWh) of the annual energy consumption is attributed to agriculture, while 75% (174,709 GWh) is used for water supply purposes. The agricultural sector consumes 77% (32,629 m 3 ) of the irrigation water, and the energy sector is vulnerable to water availability fluctuations, because many hydroelectric facilities are connected to its grid. Considering the water scarcity and the uneven geographical distribution of water in the state, its central role in California's water-energy-food (WEF) Nexus becomes apparent.

Geographies, Aug 29, 2022

Wseas Transactions On Environment And Development, Mar 31, 2020

This research work deals with an integrated assessment regarding a hydrosystem's resilience under... more This research work deals with an integrated assessment regarding a hydrosystem's resilience under changing conditions. Particularly, the analysis is performed for Florina, a rural area in Northern Greece. In Florina, four reservoirs operate to meet water requirements for agriculture and industrial use, as well as, to satisfy the urban water demand of the local population. The analysis initially includes the hydrologic simulation of the natural system that is achieved by developing and implementing a hydrologic model on a monthly basis, using the available historic data for the region. It also incorporates the development of the reservoirs' monthly water balance models to assess the reliability of the system based on the current water requirements and the historic datasets. In terms of rational water resources management under changing conditions, various combinations are investigated; all of which are based on four main scenarios (i.e., zero, three climate change scenarios, population growth scenario, scenarios regarding different distribution of irrigation water). The comparison among the aforementioned scenarios is finally shown through the variation in the hydrosystem's reliability to meet water demands. Results show that each reservoir presents its own behavior with respect to its particular technical characteristics and the scenario performed. In general, reliability decreases, while, the implementation of the scenarios that introduce different practices regarding water distribution for irrigation showed that this practice can ensure a relatively higher reliability to the local hydrosystem.

Earth, Apr 16, 2022

The non-interconnected islands of Greece can benefit from the comprehensive use of RES to avoid w... more The non-interconnected islands of Greece can benefit from the comprehensive use of RES to avoid water droughts and ensure energy autonomy. The present paper analyzes an HRES with two possible operating scenarios. Both of them include a wind park of 27.5 MW capacity, an 1175 m 3 /day desalination plant, and a 490,000 m 3 /day water tank in Lemnos, Greece. Regarding the wind power, 70% is used in the HRES, while the rest is channeled directly to the grid. The main difference comes down to how the wind energy is stored, either in the form of hydraulic energy or in the form of hydrogen. The lifespan of the system is 25 years, such as the produced stochastic series of rainfall, temperature, and wind of the area. Through the comparison of the operating scenarios, the following results arise: (i) the water needs of the island are fully covered and the irrigation needs have a reliability of 66%, in both scenarios. (ii) Considering the energy needs, the pumping storage seems to be the most reliable solution. (iii) However, depending on the amount of wind energy surplus, the use of hydrogen could produce more energy than the hydroelectric plant.

Gross rainfall, throughfall, stemflow and interception losses were measured and studied for seven... more Gross rainfall, throughfall, stemflow and interception losses were measured and studied for seven years (1996 -2002) in an evergreen schlyrophylous species (maquis) stand of eastern Mediterranean region and specifically of southern -western Greece. The monthly values were analysed and compared with the corresponding values of gross rainfall through the year. Throughfall, stemflow and interception losses were regressed, on a single rain event scale, against a number of meteorological variables. All the regression equations were found significant for at least 0.05 probability level. The models were tested with the data of 2003 by means of comparison of predicted and observed values of these components. All models yielded satisfactory estimates, especially from rainfall events greater than 10 mm.

Remote Sensing, Apr 12, 2022

Inland water resources are facing increasing quantitative and qualitative pressures, deriving fro... more Inland water resources are facing increasing quantitative and qualitative pressures, deriving from anthropogenic causes and the ongoing climate change. The monitoring of reservoirs is essential for sustainable management and preparation against water scarcity and extreme events, such as droughts. This research, relying on the Sentinel-2 and 3 missions, attempts to demonstrate the efficiency of combining remotely sensed water level and water area estimations, in order to estimate the water storage variation of Yliki reservoir. The case study is conducted in one of the few sufficiently monitored reservoirs in Greece, enabling a direct comparison of the proposed methodology results with in situ observations. Moreover, this research work proposes a weekly time interval for pairing level and area estimations, instead of shorter time intervals. The results strongly demonstrate the efficiency of remote sensing in the production of empirical level-area-storage (L-A-S) curves. Correlation to in situ monitored storage-and satellite-derived water level, area stand for 98.81% and 99.27% respectively. Water storage variation is estimated and compared to the observed time series, resulting in an RMSE of 1.28% of the reservoir capacity and a correlation of 96.14%. The empirical L-S relationship underestimates storage, while the A-S relationship overestimates storage when compared to the existing L-A-S curve.

Proceedings of the 16th International Conference on Environmental Science and Technology, Nov 19, 2022

A combined hydrological and hydraulic analysis is presented for an extreme flood event occurred o... more A combined hydrological and hydraulic analysis is presented for an extreme flood event occurred on February 6, 2012 in Sperchios River Basin, located in Central Greece. This event caused the river's overflow and, consequently, several damages to infrastructure and agricultural land. Sperchios River Basin is a case of ungauged basin and only rainfall measurements of fine temporal scale are available. The hydrological analysis was performed with the aid of the Hydrologic Modeling System (HEC-HMS) to incorporate and combine different methods concerning the rainfall-runoff transformation, the hydrological losses, the river routing and the baseflow recession, and finally to generate the flood hydrograph. The hydrological analysis output was then used in the River Analysis System (HEC-RAS), which has the ability to model unsteady flow through a river channel network and produces the water profiles, velocity and inundation maps of the flood plain. The implementation of this integrated model for historic flood events in such ungauged basins is useful for reducing the uncertainty and developing robust flood forecasting and early warning systems in order to reduce life casualties and mitigate losses due to flooding.

Circular Economy and Sustainability, Aug 10, 2021

This paper describes an approach for the identification of flood-susceptible areas contributing t... more This paper describes an approach for the identification of flood-susceptible areas contributing to the sustainability of these in the Giofiros river basin covering an area of 184 km 2 , located in Southern Greece. This basin is prone to flooding with devastating consequences on people, environment, and the economy. In this context, a geographic information system (GIS)-based multi-criteria decision analysis (MCDA) method for the identification of potential flood-prone areas at basin scale is initially presented. Upstream of the very high flood-susceptible areas of a simulated point is selected, which is the outlet of the created subbasin (169 km 2 ). In this area, a hydrological analysis is conducted based on the unit hydrograph (UH) theory simulating the rainfall-runoff process. The UH is calculated by applying three different methods: the time-area diagram method into the GIS environment, the Soil Conservation Service (SCS) UH, and the Snyder synthetic UH. The results show that the two last methods underestimate the flood peak in relation to the results of the time-area diagram method. The hydrological analysis is completed through Hydrologic Modeling System (HEC-HMS) software from which three flood hydrographs are produced. The flood hydrograph calculated using the time-area diagram method is imported into the River Analysis System (HEC-RAS) software in order for a hydraulic simulation to be performed. The simulation output resulted in flood hazard mapping with the maximum depth and maximum velocity along the simulated section of the mainstream downstream of the simulated point. The results of this approach appear to be extremely useful for preventing flood disaster and making disaster mitigation plans. Keywords Flood-susceptible areas . GIS-based multi-criteria decision analysis . Time-area diagram . Flood hazard map

Water Resources Management, Dec 15, 2011

Discharges in a network of drainage ditches generated by intense rainfall are influenced by overl... more Discharges in a network of drainage ditches generated by intense rainfall are influenced by overland flow dynamically interacting with infiltration. Therefore a detailed estimation of the overland flow, especially in agricultural fields prepared for surface irrigation, is essential to the design of drainage ditches. In order to simulate overland flow, which in that case may be considered unsteady and one dimensional, numerical models were developed based on the numerical solution of the Saint-Venant equations, externally coupled with the Green-Ampt equation to account for the dynamic interaction between surface flow and infiltration. The numerical solution of the Saint Venant equations in their complete form (dynamic model) and in the simplified forms of the diffusion (diffusion model) and the kinematic wave equations (kinematic model) was obtained by applying the MacCormack explicit computational scheme. Overland flow models' simulations were conducted in order to study the effect of the soil surface parameters on the hydrographs at the downstream end of the fields, as well as the accuracy of the diffusion and kinematic equations. It was found that the kinematic wave equations were unable to describe overland flow, while the diffusion model results were close to the results of the dynamic model.

Water, Aug 15, 2019

Five different water resource management scenarios are examined on eight dry islands of the Aegea... more Five different water resource management scenarios are examined on eight dry islands of the Aegean Sea in Greece, pitting the current practice of water hauling via ship against alternative water supply schemes in delivering a sustainable solution for meeting water demand. The first scenario employs current water supply practices along with the operation of domestic rainwater harvesting systems. Desalinated water, provided through the operation of wind-powered desalination plants, is considered the main source of potable water in the rest of scenarios. Wind-powered desalination may be combined with rainwater harvesting as a supplementary source of water and/or seawater pumping and an additional source of energy that is supplied to the system. All different alternatives are evaluated for a 30-year lifespan, and an optimal solution is proposed for each island, based on a life cycle cost (LCC) analysis. The performance of this solution is then assessed under six climate change (CC) scenarios in terms of the rate of on-grid versus off-grid renewable energy that is required in order to achieve a certain reliability level. Overall, the examined scenarios show a decreasing performance in terms of reliability under CC for the eight islands.

Journal of Flood Risk Management, Sep 2, 2019

The identification of flood-prone areas is a fundamental component of rational urban planning and... more The identification of flood-prone areas is a fundamental component of rational urban planning and proper natural disaster management policy. The aim of the present study is to introduce a framework for the identification of flood-prone areas using geographical information systems techniques and decision-making, based on a comparative evaluation for various scenarios. As a case study, the Attica region in Greece is selected, which is occasionally affected by heavy rainfall, the main cause of flooding in the region, coupled with the fact that human activities and urbanization of recent years play a significant role in flood occurrence. In this context, the development and application of a GIS-based multi-criteria analysis method for the determination of areas susceptible to flood events is initially presented. The entire spatial analysis is performed using SAGA 6.3.0 and ArcMap 10.2 Desktop, by applying a number of alternative modifications and, finally, by evaluating different scenarios regarding methods for the criteria standardization, criteria hierarchy and factors' weighting estimation. The proposed framework has an advantage among other approaches, since it takes into account mainly static data that are linked to flooding, such as the topography and land cover distribution and it can be easily customized in ungauged catchments.

Hydrology and Earth System Sciences, Nov 26, 2007

The present study was conducted in an experimental watershed in Attica, Greece, using observed ra... more The present study was conducted in an experimental watershed in Attica, Greece, using observed rainfall/runoff events. The objective of the study was the determination of the initial abstraction ratio of the watershed. The average ratio (Ia/S) of the entire watershed was equal to 0.014. The corresponding ratio at a subwatershed was 0.037. The difference was attributed to the different spatial distribution of landuses and geological formations at the extent of the watershed. Both of the determined ratios are close to the ratio value of 0.05 that has been suggested from many studies for the improvement of the SCS-CN method.

Wseas Transactions On Environment And Development, May 5, 2020

The prolonged issues regarding the quantita tive and qualitative characteristics of the water res... more The prolonged issues regarding the quantita tive and qualitative characteristics of the water resources in the River Basin District of Thessaly (TRBD) have resulted in the environm ental degradation and the reduction of the availability of water. Agriculture is t he major water user, constituting up to 95% of total water demand. The pressures anticipated from the ongoing climate change are expected to cause further degradation, given the present status of the water resources. This research attempts to examine and quantify the water saving potential of TRBD, mainly for the agriculture sector, following the recommendations of the European legislation, the principles of sustainab le development and environmental protection. Water saving t ools are documented in several countries, incl uding technical measures, such as dr ip irrigation sy stems and the modernization of the transfer networks , as well as deficit and scheduled irrigation practices and water reuse. These measures and pract ices are tested for their poten tial effect on water dem and in TR BD, in addition to changing a portion of cott on cultivation areas to olive grov es. To this end, the volume of i rrigation demand is estimated at 2088×10 6 , while total water demand stands for 2204×10 6 . Afterwards the study proceeds to the evaluation of the water saving potential both independently and combined. The potential of water savings in TRBD is proven high, 14.3% of total water demand for technical measures, 10.7% if deficit irrigation is applied to specific crops, while it may reach 28.8% in case the measures are combined.

Hydrology, Sep 10, 2021

Identifying the core hydrological processes of catchments is a critical step for operative hydrol... more Identifying the core hydrological processes of catchments is a critical step for operative hydrological modeling. This study attempts to assess the long-term alterations in streamflow in three adjacent catchments of Upper East Fork White River, Indiana USA, by employing the SWAT hydrological model. The model simulations are spanning from 1980 up to 2015 and distributed in three configurations periods to identify monthly alterations in streamflow. For this purpose, water abstraction, land use, tillage, and agricultural field drainage practices have been incorporated in the model to provide accurate data input. The model setup also integrates spatially disaggregated sectorial water use data from surface and groundwater resources integrating the significant increases of water abstractions mainly for agricultural and public water supply purposes. The land cover of the study area is governed by rotating crops, while agricultural practices and tile drainage are crucial model parameters affecting the regional hydrological balance. Streamflow prediction is based on the SUFI-2 algorithm and the SWAT-CUP interface has been used for the monthly calibration and validation phases of the model. The evaluation of model simulations indicate a progressively sufficient hydrological model setup for all configuration periods with NSE (0.87, 0.88, and 0.88) and PBIAS (14%, -7%, and -2.8%) model evaluation values at the Seymour outlet. Surface runoff/precipitation as well as percolation/precipitation ratios have been used as indicators to identify trends to wetter conditions. Model outputs for the upstream areas, are successful predictions for streamflow assessment studies to test future implications of land cover and climate change.

Proceedings of the 16th International Conference on Environmental Science and Technology, Nov 19, 2022

EGU General Assembly Conference Abstracts, Apr 1, 2009

Advances in sciences and engineering, Jun 25, 2020

Water scarcity is a serious problem for the Aegean Islands in Greece. Due to the fact that touris... more Water scarcity is a serious problem for the Aegean Islands in Greece. Due to the fact that tourist development grows in a continuous way, the situation has deteriorated over the last years. Current water resources management practices involving the exploitation of the groundwater reservoirs have provoked the salty water intrusion into the aquifers and in many arid islands water is transported by sea, at a considerably high cost (reaches about 12 €/m³ in some cases). Desalination is foreseen as a solution to this problem and it has already been adopted in many islands, as it is a process that can provide fresh and potable water in the required quantities, at a much lower cost. The coupling of desalination with renewable energy sources (RES) constitutes an appealing and promising option. This paper presents an integrated case study regarding the design and operation of a waterenergy system for meeting irrigation and potable water demand in Lipsi Island (Dodecanese complex, Greece). As the desalination unit operation depends on the wind power, a detailed description regarding the generation of synthetic time series of wind speed data is also presented. Finally, a Cost-Benefit Analysis is carried out to discuss each scenario we examine from a financial perspective.

Advances in science, technology & innovation, Sep 19, 2019

Three different scenarios for meeting domestic water demand in a small island in Greece were exam... more Three different scenarios for meeting domestic water demand in a small island in Greece were examined and compared. Life-cycle cost analysis was performed in order to evaluate each scenario from an economic point of view.

Research Square (Research Square), Mar 11, 2021

The design of an optimum hydrometeorological and hydrometric station network constitutes a key fa... more The design of an optimum hydrometeorological and hydrometric station network constitutes a key factor for the collection of comprehensive and reliable hydrometeorological and ow data that are necessary both for decision making in water resources policy and management and for the hydrometeorological risk assessment. This article describes a methodology developed in a geographic information system (GIS) assisted by a multicriteria decision making (MCDM) approach, which combines a set of spatial criteria in order to propose suitable locations for such a station network installation. Through the design for two networks that meet different requirements, various aspects concerning this methodology are illustrated, such as, the methods regarding criteria classi cation and weighting, as well as, the effect of weighting itself on the location rating. In particular, the implementation is performed for the Sarantapotamos river basin, an area located in the western part of Attica region, Greece, which is characterized by a great diversity of economic activities, mainly industrial, rural and urban fabric in the lowlands. Finally, the analysis indicates that, in terms of station density as proposed by the World Meteorological Organization (WMO), the optimum hydrometeorological station network consists of three stations and the hydrometric one of two stations.

Στην παρούσα eργασία πeριγράφeται η eφαρμογή eνός υδρολογικού μοντέλου σe συγκeντρωτική μορφή στη... more Στην παρούσα eργασία πeριγράφeται η eφαρμογή eνός υδρολογικού μοντέλου σe συγκeντρωτική μορφή στη λeκάνη του ποταμού Πορταϊκού (λeκάνη της Πύλης). Η πeριοχή μeλέτης βρίσκeται σe ακτίνα 100 km από τη θέση του ραντάρ και συχνά υποφέρeι απο καταστροφικές πλημμύρeς. Το μeτeωρολογικό ραντάρ που χρησιμοποιήθηκe για την ποσοτική eκτίμηση της βροχής eίναι το WSR-74 S-band ραντάρ, eγκατeστημένο στην αeροπορική βάση της Λάρισας. Τα πρωτογeνή στοιχeία του ραντάρ αναλύθηκαν και υποβλήθηκαν σe eπeξeργασία για τη δημιουργία ποιοτικώς αναβαθμισμένων πeδίων βροχής τα οποία θα χρησιμοποιηθούν πeραιτέρω ως eίσοδοι στο υδρολογικό μοντέλο. Το υδρολογικό μοντέλο χρησιμοποιήθηκe σe δύο διαφορeτικές πeριπτώσeις μe καλά αποτeλέσματα. Στην πρώτη πeρίπτωση ως eίσοδος στο μοντέλο χρησιμοποιήθηκe η μέση ωριαία eπιφανeιακή βροχόπτωση που προέκυψe από τα στοιχeία των βροχογράφων, eνώ στη δeύτeρη πeρίπτωση χρησιμοποιήθηκe η μέση ωριαία eπιφανeιακή βροχόπτωση που προέκυψe από eπeξeργασμένα (σe συνδυασμό μe στοιχeί...

Environmental sciences proceedings, Aug 18, 2020

The current analysis attempts to quantify the interlinkages between the water, energy and food se... more The current analysis attempts to quantify the interlinkages between the water, energy and food sectors of California covering the period 2002-2015. The results reveal that 25% (60,696 GWh) of the annual energy consumption is attributed to agriculture, while 75% (174,709 GWh) is used for water supply purposes. The agricultural sector consumes 77% (32,629 m 3 ) of the irrigation water, and the energy sector is vulnerable to water availability fluctuations, because many hydroelectric facilities are connected to its grid. Considering the water scarcity and the uneven geographical distribution of water in the state, its central role in California's water-energy-food (WEF) Nexus becomes apparent.

Geographies, Aug 29, 2022

Wseas Transactions On Environment And Development, Mar 31, 2020

This research work deals with an integrated assessment regarding a hydrosystem's resilience under... more This research work deals with an integrated assessment regarding a hydrosystem's resilience under changing conditions. Particularly, the analysis is performed for Florina, a rural area in Northern Greece. In Florina, four reservoirs operate to meet water requirements for agriculture and industrial use, as well as, to satisfy the urban water demand of the local population. The analysis initially includes the hydrologic simulation of the natural system that is achieved by developing and implementing a hydrologic model on a monthly basis, using the available historic data for the region. It also incorporates the development of the reservoirs' monthly water balance models to assess the reliability of the system based on the current water requirements and the historic datasets. In terms of rational water resources management under changing conditions, various combinations are investigated; all of which are based on four main scenarios (i.e., zero, three climate change scenarios, population growth scenario, scenarios regarding different distribution of irrigation water). The comparison among the aforementioned scenarios is finally shown through the variation in the hydrosystem's reliability to meet water demands. Results show that each reservoir presents its own behavior with respect to its particular technical characteristics and the scenario performed. In general, reliability decreases, while, the implementation of the scenarios that introduce different practices regarding water distribution for irrigation showed that this practice can ensure a relatively higher reliability to the local hydrosystem.

Earth, Apr 16, 2022

The non-interconnected islands of Greece can benefit from the comprehensive use of RES to avoid w... more The non-interconnected islands of Greece can benefit from the comprehensive use of RES to avoid water droughts and ensure energy autonomy. The present paper analyzes an HRES with two possible operating scenarios. Both of them include a wind park of 27.5 MW capacity, an 1175 m 3 /day desalination plant, and a 490,000 m 3 /day water tank in Lemnos, Greece. Regarding the wind power, 70% is used in the HRES, while the rest is channeled directly to the grid. The main difference comes down to how the wind energy is stored, either in the form of hydraulic energy or in the form of hydrogen. The lifespan of the system is 25 years, such as the produced stochastic series of rainfall, temperature, and wind of the area. Through the comparison of the operating scenarios, the following results arise: (i) the water needs of the island are fully covered and the irrigation needs have a reliability of 66%, in both scenarios. (ii) Considering the energy needs, the pumping storage seems to be the most reliable solution. (iii) However, depending on the amount of wind energy surplus, the use of hydrogen could produce more energy than the hydroelectric plant.

Gross rainfall, throughfall, stemflow and interception losses were measured and studied for seven... more Gross rainfall, throughfall, stemflow and interception losses were measured and studied for seven years (1996 -2002) in an evergreen schlyrophylous species (maquis) stand of eastern Mediterranean region and specifically of southern -western Greece. The monthly values were analysed and compared with the corresponding values of gross rainfall through the year. Throughfall, stemflow and interception losses were regressed, on a single rain event scale, against a number of meteorological variables. All the regression equations were found significant for at least 0.05 probability level. The models were tested with the data of 2003 by means of comparison of predicted and observed values of these components. All models yielded satisfactory estimates, especially from rainfall events greater than 10 mm.

Remote Sensing, Apr 12, 2022

Inland water resources are facing increasing quantitative and qualitative pressures, deriving fro... more Inland water resources are facing increasing quantitative and qualitative pressures, deriving from anthropogenic causes and the ongoing climate change. The monitoring of reservoirs is essential for sustainable management and preparation against water scarcity and extreme events, such as droughts. This research, relying on the Sentinel-2 and 3 missions, attempts to demonstrate the efficiency of combining remotely sensed water level and water area estimations, in order to estimate the water storage variation of Yliki reservoir. The case study is conducted in one of the few sufficiently monitored reservoirs in Greece, enabling a direct comparison of the proposed methodology results with in situ observations. Moreover, this research work proposes a weekly time interval for pairing level and area estimations, instead of shorter time intervals. The results strongly demonstrate the efficiency of remote sensing in the production of empirical level-area-storage (L-A-S) curves. Correlation to in situ monitored storage-and satellite-derived water level, area stand for 98.81% and 99.27% respectively. Water storage variation is estimated and compared to the observed time series, resulting in an RMSE of 1.28% of the reservoir capacity and a correlation of 96.14%. The empirical L-S relationship underestimates storage, while the A-S relationship overestimates storage when compared to the existing L-A-S curve.

Proceedings of the 16th International Conference on Environmental Science and Technology, Nov 19, 2022

A combined hydrological and hydraulic analysis is presented for an extreme flood event occurred o... more A combined hydrological and hydraulic analysis is presented for an extreme flood event occurred on February 6, 2012 in Sperchios River Basin, located in Central Greece. This event caused the river's overflow and, consequently, several damages to infrastructure and agricultural land. Sperchios River Basin is a case of ungauged basin and only rainfall measurements of fine temporal scale are available. The hydrological analysis was performed with the aid of the Hydrologic Modeling System (HEC-HMS) to incorporate and combine different methods concerning the rainfall-runoff transformation, the hydrological losses, the river routing and the baseflow recession, and finally to generate the flood hydrograph. The hydrological analysis output was then used in the River Analysis System (HEC-RAS), which has the ability to model unsteady flow through a river channel network and produces the water profiles, velocity and inundation maps of the flood plain. The implementation of this integrated model for historic flood events in such ungauged basins is useful for reducing the uncertainty and developing robust flood forecasting and early warning systems in order to reduce life casualties and mitigate losses due to flooding.

Circular Economy and Sustainability, Aug 10, 2021

This paper describes an approach for the identification of flood-susceptible areas contributing t... more This paper describes an approach for the identification of flood-susceptible areas contributing to the sustainability of these in the Giofiros river basin covering an area of 184 km 2 , located in Southern Greece. This basin is prone to flooding with devastating consequences on people, environment, and the economy. In this context, a geographic information system (GIS)-based multi-criteria decision analysis (MCDA) method for the identification of potential flood-prone areas at basin scale is initially presented. Upstream of the very high flood-susceptible areas of a simulated point is selected, which is the outlet of the created subbasin (169 km 2 ). In this area, a hydrological analysis is conducted based on the unit hydrograph (UH) theory simulating the rainfall-runoff process. The UH is calculated by applying three different methods: the time-area diagram method into the GIS environment, the Soil Conservation Service (SCS) UH, and the Snyder synthetic UH. The results show that the two last methods underestimate the flood peak in relation to the results of the time-area diagram method. The hydrological analysis is completed through Hydrologic Modeling System (HEC-HMS) software from which three flood hydrographs are produced. The flood hydrograph calculated using the time-area diagram method is imported into the River Analysis System (HEC-RAS) software in order for a hydraulic simulation to be performed. The simulation output resulted in flood hazard mapping with the maximum depth and maximum velocity along the simulated section of the mainstream downstream of the simulated point. The results of this approach appear to be extremely useful for preventing flood disaster and making disaster mitigation plans. Keywords Flood-susceptible areas . GIS-based multi-criteria decision analysis . Time-area diagram . Flood hazard map

Water Resources Management, Dec 15, 2011

Discharges in a network of drainage ditches generated by intense rainfall are influenced by overl... more Discharges in a network of drainage ditches generated by intense rainfall are influenced by overland flow dynamically interacting with infiltration. Therefore a detailed estimation of the overland flow, especially in agricultural fields prepared for surface irrigation, is essential to the design of drainage ditches. In order to simulate overland flow, which in that case may be considered unsteady and one dimensional, numerical models were developed based on the numerical solution of the Saint-Venant equations, externally coupled with the Green-Ampt equation to account for the dynamic interaction between surface flow and infiltration. The numerical solution of the Saint Venant equations in their complete form (dynamic model) and in the simplified forms of the diffusion (diffusion model) and the kinematic wave equations (kinematic model) was obtained by applying the MacCormack explicit computational scheme. Overland flow models' simulations were conducted in order to study the effect of the soil surface parameters on the hydrographs at the downstream end of the fields, as well as the accuracy of the diffusion and kinematic equations. It was found that the kinematic wave equations were unable to describe overland flow, while the diffusion model results were close to the results of the dynamic model.

Water, Aug 15, 2019

Five different water resource management scenarios are examined on eight dry islands of the Aegea... more Five different water resource management scenarios are examined on eight dry islands of the Aegean Sea in Greece, pitting the current practice of water hauling via ship against alternative water supply schemes in delivering a sustainable solution for meeting water demand. The first scenario employs current water supply practices along with the operation of domestic rainwater harvesting systems. Desalinated water, provided through the operation of wind-powered desalination plants, is considered the main source of potable water in the rest of scenarios. Wind-powered desalination may be combined with rainwater harvesting as a supplementary source of water and/or seawater pumping and an additional source of energy that is supplied to the system. All different alternatives are evaluated for a 30-year lifespan, and an optimal solution is proposed for each island, based on a life cycle cost (LCC) analysis. The performance of this solution is then assessed under six climate change (CC) scenarios in terms of the rate of on-grid versus off-grid renewable energy that is required in order to achieve a certain reliability level. Overall, the examined scenarios show a decreasing performance in terms of reliability under CC for the eight islands.

Journal of Flood Risk Management, Sep 2, 2019

The identification of flood-prone areas is a fundamental component of rational urban planning and... more The identification of flood-prone areas is a fundamental component of rational urban planning and proper natural disaster management policy. The aim of the present study is to introduce a framework for the identification of flood-prone areas using geographical information systems techniques and decision-making, based on a comparative evaluation for various scenarios. As a case study, the Attica region in Greece is selected, which is occasionally affected by heavy rainfall, the main cause of flooding in the region, coupled with the fact that human activities and urbanization of recent years play a significant role in flood occurrence. In this context, the development and application of a GIS-based multi-criteria analysis method for the determination of areas susceptible to flood events is initially presented. The entire spatial analysis is performed using SAGA 6.3.0 and ArcMap 10.2 Desktop, by applying a number of alternative modifications and, finally, by evaluating different scenarios regarding methods for the criteria standardization, criteria hierarchy and factors' weighting estimation. The proposed framework has an advantage among other approaches, since it takes into account mainly static data that are linked to flooding, such as the topography and land cover distribution and it can be easily customized in ungauged catchments.

Hydrology and Earth System Sciences, Nov 26, 2007

The present study was conducted in an experimental watershed in Attica, Greece, using observed ra... more The present study was conducted in an experimental watershed in Attica, Greece, using observed rainfall/runoff events. The objective of the study was the determination of the initial abstraction ratio of the watershed. The average ratio (Ia/S) of the entire watershed was equal to 0.014. The corresponding ratio at a subwatershed was 0.037. The difference was attributed to the different spatial distribution of landuses and geological formations at the extent of the watershed. Both of the determined ratios are close to the ratio value of 0.05 that has been suggested from many studies for the improvement of the SCS-CN method.

Wseas Transactions On Environment And Development, May 5, 2020

The prolonged issues regarding the quantita tive and qualitative characteristics of the water res... more The prolonged issues regarding the quantita tive and qualitative characteristics of the water resources in the River Basin District of Thessaly (TRBD) have resulted in the environm ental degradation and the reduction of the availability of water. Agriculture is t he major water user, constituting up to 95% of total water demand. The pressures anticipated from the ongoing climate change are expected to cause further degradation, given the present status of the water resources. This research attempts to examine and quantify the water saving potential of TRBD, mainly for the agriculture sector, following the recommendations of the European legislation, the principles of sustainab le development and environmental protection. Water saving t ools are documented in several countries, incl uding technical measures, such as dr ip irrigation sy stems and the modernization of the transfer networks , as well as deficit and scheduled irrigation practices and water reuse. These measures and pract ices are tested for their poten tial effect on water dem and in TR BD, in addition to changing a portion of cott on cultivation areas to olive grov es. To this end, the volume of i rrigation demand is estimated at 2088×10 6 , while total water demand stands for 2204×10 6 . Afterwards the study proceeds to the evaluation of the water saving potential both independently and combined. The potential of water savings in TRBD is proven high, 14.3% of total water demand for technical measures, 10.7% if deficit irrigation is applied to specific crops, while it may reach 28.8% in case the measures are combined.

Hydrology, Sep 10, 2021

Identifying the core hydrological processes of catchments is a critical step for operative hydrol... more Identifying the core hydrological processes of catchments is a critical step for operative hydrological modeling. This study attempts to assess the long-term alterations in streamflow in three adjacent catchments of Upper East Fork White River, Indiana USA, by employing the SWAT hydrological model. The model simulations are spanning from 1980 up to 2015 and distributed in three configurations periods to identify monthly alterations in streamflow. For this purpose, water abstraction, land use, tillage, and agricultural field drainage practices have been incorporated in the model to provide accurate data input. The model setup also integrates spatially disaggregated sectorial water use data from surface and groundwater resources integrating the significant increases of water abstractions mainly for agricultural and public water supply purposes. The land cover of the study area is governed by rotating crops, while agricultural practices and tile drainage are crucial model parameters affecting the regional hydrological balance. Streamflow prediction is based on the SUFI-2 algorithm and the SWAT-CUP interface has been used for the monthly calibration and validation phases of the model. The evaluation of model simulations indicate a progressively sufficient hydrological model setup for all configuration periods with NSE (0.87, 0.88, and 0.88) and PBIAS (14%, -7%, and -2.8%) model evaluation values at the Seymour outlet. Surface runoff/precipitation as well as percolation/precipitation ratios have been used as indicators to identify trends to wetter conditions. Model outputs for the upstream areas, are successful predictions for streamflow assessment studies to test future implications of land cover and climate change.

Proceedings of the 16th International Conference on Environmental Science and Technology, Nov 19, 2022

EGU General Assembly Conference Abstracts, Apr 1, 2009

Advances in sciences and engineering, Jun 25, 2020

Water scarcity is a serious problem for the Aegean Islands in Greece. Due to the fact that touris... more Water scarcity is a serious problem for the Aegean Islands in Greece. Due to the fact that tourist development grows in a continuous way, the situation has deteriorated over the last years. Current water resources management practices involving the exploitation of the groundwater reservoirs have provoked the salty water intrusion into the aquifers and in many arid islands water is transported by sea, at a considerably high cost (reaches about 12 €/m³ in some cases). Desalination is foreseen as a solution to this problem and it has already been adopted in many islands, as it is a process that can provide fresh and potable water in the required quantities, at a much lower cost. The coupling of desalination with renewable energy sources (RES) constitutes an appealing and promising option. This paper presents an integrated case study regarding the design and operation of a waterenergy system for meeting irrigation and potable water demand in Lipsi Island (Dodecanese complex, Greece). As the desalination unit operation depends on the wind power, a detailed description regarding the generation of synthetic time series of wind speed data is also presented. Finally, a Cost-Benefit Analysis is carried out to discuss each scenario we examine from a financial perspective.

Advances in science, technology & innovation, Sep 19, 2019

Three different scenarios for meeting domestic water demand in a small island in Greece were exam... more Three different scenarios for meeting domestic water demand in a small island in Greece were examined and compared. Life-cycle cost analysis was performed in order to evaluate each scenario from an economic point of view.

Research Square (Research Square), Mar 11, 2021

The design of an optimum hydrometeorological and hydrometric station network constitutes a key fa... more The design of an optimum hydrometeorological and hydrometric station network constitutes a key factor for the collection of comprehensive and reliable hydrometeorological and ow data that are necessary both for decision making in water resources policy and management and for the hydrometeorological risk assessment. This article describes a methodology developed in a geographic information system (GIS) assisted by a multicriteria decision making (MCDM) approach, which combines a set of spatial criteria in order to propose suitable locations for such a station network installation. Through the design for two networks that meet different requirements, various aspects concerning this methodology are illustrated, such as, the methods regarding criteria classi cation and weighting, as well as, the effect of weighting itself on the location rating. In particular, the implementation is performed for the Sarantapotamos river basin, an area located in the western part of Attica region, Greece, which is characterized by a great diversity of economic activities, mainly industrial, rural and urban fabric in the lowlands. Finally, the analysis indicates that, in terms of station density as proposed by the World Meteorological Organization (WMO), the optimum hydrometeorological station network consists of three stations and the hydrometric one of two stations.

Στην παρούσα eργασία πeριγράφeται η eφαρμογή eνός υδρολογικού μοντέλου σe συγκeντρωτική μορφή στη... more Στην παρούσα eργασία πeριγράφeται η eφαρμογή eνός υδρολογικού μοντέλου σe συγκeντρωτική μορφή στη λeκάνη του ποταμού Πορταϊκού (λeκάνη της Πύλης). Η πeριοχή μeλέτης βρίσκeται σe ακτίνα 100 km από τη θέση του ραντάρ και συχνά υποφέρeι απο καταστροφικές πλημμύρeς. Το μeτeωρολογικό ραντάρ που χρησιμοποιήθηκe για την ποσοτική eκτίμηση της βροχής eίναι το WSR-74 S-band ραντάρ, eγκατeστημένο στην αeροπορική βάση της Λάρισας. Τα πρωτογeνή στοιχeία του ραντάρ αναλύθηκαν και υποβλήθηκαν σe eπeξeργασία για τη δημιουργία ποιοτικώς αναβαθμισμένων πeδίων βροχής τα οποία θα χρησιμοποιηθούν πeραιτέρω ως eίσοδοι στο υδρολογικό μοντέλο. Το υδρολογικό μοντέλο χρησιμοποιήθηκe σe δύο διαφορeτικές πeριπτώσeις μe καλά αποτeλέσματα. Στην πρώτη πeρίπτωση ως eίσοδος στο μοντέλο χρησιμοποιήθηκe η μέση ωριαία eπιφανeιακή βροχόπτωση που προέκυψe από τα στοιχeία των βροχογράφων, eνώ στη δeύτeρη πeρίπτωση χρησιμοποιήθηκe η μέση ωριαία eπιφανeιακή βροχόπτωση που προέκυψe από eπeξeργασμένα (σe συνδυασμό μe στοιχeί...