Virtual Water is a recently introduced and widely recognized concept that is considered important... more Virtual Water is a recently introduced and widely recognized concept that is considered important for attaining regional and global water security. It refers to the water needed for the production of an agricultural or industrial product and it is contained in the product not in real but in virtual sense. The practical importance of the virtual water concept is mainly twofold, as virtual water trade can act as a tool to achieve water security and efficient water use, while water footprints can act as links between consumption patterns and the impacts on water. This paper applies the virtual water concept at regional level using the Prefectures of Xanthi and Rhodope as case studies. The ensuing results are juxtaposed and commented.
The scope of the present study was to predict the shoreline change in the wider area of the Port ... more The scope of the present study was to predict the shoreline change in the wider area of the Port of Alexandroupolis, forty years from today. In order to achieve our goal, we used the commercial software package CEDAS (Coastal Engineering Design and Analysis System) and in particular, the numerical models of NEMOS (NEMOS is a part of CEDAS software). The most important input data (referring to the study area) for the numerical models of NEMOS were: bathymetric data, the port of Alexandroupolis, relative wave timeseries in deep water conditions which are application results of the model WAM performed for the Aegean Sea by H.C.M.R., and past and contemporary shorelines of the area which were produced by processing satellite images and field measurements. The extracted shorelines were used as reference shorelines in the sensitivity tests and the calibration of NEMOS models. The simulation results, show the parts of the study area which are under erosion and those which are under accretion.
The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-G... more The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-Greece-Turkey) river Evros/Maritza has increased dramatically in the last 13 years. It is not clear if the increase of flood frequency is due to climatic changes or to inappropriate management of Bulgarian dams. This fact raises the question of modeling the flood routing through the many dams in the Bulgarian territory (upstream), which receive the runoff of the 38% of the area of the Evros watershed in Bulgaria, in a way to protect the downstream countries from flooding. The basic objective of this paper is the development of a new management tool (software) for the simulation of the rainfall-runoff and routing process taking into account the existence of many dams and mainly their operation not only from a hydrologic viewpoint, but also from the administrative, with emphasis on the "energy-economic" exploitation of the reservoirs. The developed software (named Evrofloods) models the rainfall-runoff, the routing of runoff through the various Evros river tributaries taking in account various scenarios of the runoff through the artificial reservoirs with the aim of optimal management of the water released from the dams spillways and turbines. The "optimal management" is related with the finding for a given rainfall distribution, the appropriate combination of actions at many reservoirs ("reservoirs management") in order to prevent or mitigate the floods downstream, aiming at the same time to minimize hydroelectric energy loss. Although Evrofloods software is basically dedicated to the large Evros basin, it can be easily used to determine the management of large transboundary rivers with many artificial reservoirs to avoid floods downstream. Recent European legislation on floods encourages the good cooperation of neighbor countries, to avoid floods.
The coastal zone is a transitory zone between land and sea. Due to its importance to man, not onl... more The coastal zone is a transitory zone between land and sea. Due to its importance to man, not only for its high food production but also for recreation, sea transportation and industrial activities, coastal zone receives high environmental pressure from him. This paper deals with degradation phenomena of the coastal zone in the west section of the River Nestos Delta, North Aegean Sea, with special stress on the geomorphological changes in the coastline. The length of the coastline in this part of river Nestos Delta (the Kavala-Chrisoupoli part), from Nea Karvali village to the west, up to the river mouth to the east, is around 35 km long. This section constitutes the biggest and more extended sector of the Nestos Delta; it is the section where the main course and the various branches of the river were located, in the past. Along the coastal zone of this section of the delta many lagoons, sand bars, spits, barrier islands, washover fans, etc. were developed in its geologic past. Some of these geoforms still exist, but the majority of them have been destroyed by physical and/or anthropogenic interventions. Two of the last interventions are the diversion and entrenchment of the river to the east, in early 50's and the construction of two high dams in the river course inland, in 2000. These human interventions deprived this land of flooding waters and sediments resulting in: (a) drying of most of the river channels and courses crossing this area of the river's delta, (b) erosion of the coastal landforms and retreat of the shoreline in the majority of the delta coasts. There are, of course, a few places along the coastline where deposition and accretion are still taking place. In more detail, along the coastline taken into consideration in the present paper, one can meet: • stretches with high erosion rates, like the Akroneri Cape (spit), the inner coastline of Keramoti bay (Kokala-Piges coast), the Monastiraki coastline, etc, • stretches with high accretion rates like the Keramoti peninsula/spit, and • stretches at equilibrium or low rate of change like the barrier (spit) west of Akroneri Cape up to Nea Karvali coast and a short stretch of the coastline southeast of Keramoti peninsula. Comparing the Delta coastline of 1945 (from available aerial photographs) and the coastline of 2002 (from high resolution satellite images), before the construction of the Thisavros and Platanovrisi high dams (period 1945-2002), it has been estimated that: 88% of the delta and the adjacent coastlines has been accreted while only 12% has been eroded. In other words, there was a surplus of accretion by 76% and the delta was procreated. Comparing the Delta coastline of 2002 (from high resolution satellite images) and the coastline of 2007 (from high resolution D-GPS field measurements), after the construction of the dams (period 2002-2007), it has been estimated that: only 39% of the delta and the adjacent coastlines has been accreted while 61% has been eroded. In other words, there was a surplus of erosion by 22% and the delta began to retreat.
We consider the problem of the vertically upwards disposal of heavy brine sewage from a two-dimen... more We consider the problem of the vertically upwards disposal of heavy brine sewage from a two-dimensional diffuser in a lighter, homogeneous, motionless and shallow ambient sea. The rejected high salinity water of seawater desalination plants for urban and agricultural uses is such a case of a two dimensional fountain. The disposal of brine sewage produces a negative buoyant jet due to its initial momentum, which impinges on the free surface, spreads laterally on it and then sinks downwards, because of the negative buoyancy. Laboratory experiments and dimensional considerations are used in this paper in order to investigate the spreading behavior (width) of the vertical fountain which impinges on the free surface of the shallow ambient fluid. The experimental results have been used to derive an equation relating the width at the free surface with the initial parameters of the flow. In addition, the experimentally measured dilution of the heavier brine sewage on the recipient’s surface is compared with the dilution which was calculated by a numerical simulation of a well-known commercial software package, CORJET (a CORMIX sub model).
Computational Water, Energy, and Environmental Engineering
Major flood events occurred in the Arda River region in the last decades with great economic, soc... more Major flood events occurred in the Arda River region in the last decades with great economic, social and environmental effects. A specific software package has been developed for the simulation of the flood runoff and routing process of the transboundary Arda River basin. The software package is taking into account the existence of the three cascade Bulgarian reservoirs aiming to flood protection and power optimization. Inflow estimations for duration of five days ahead and initial water levels at the three reservoirs are imported at the beginning of the simulation. The management tool includes all the alternative operation modes of hydropower plants, water released from spillways, and river and reservoir flow characteristics in order to optimize the total system (power generation and flooding costs) during the flood event. The developed software is also an efficient tool for the establishment of a flood warning system.
4th National Conference “Management and Improvement of Coastal Zones”, Sep 2008
The scope of the present study was to predict the shoreline change in the wider area of the Port ... more The scope of the present study was to predict the shoreline change in the wider area of the Port of Alexandroupolis, forty years from today. In order to achieve our goal, we used the commercial software package CEDAS (Coastal Engineering Design and Analysis System) and in particular, the numerical models of NEMOS (NEMOS is a part of CEDAS software). The most important input data (referring to the study area) for the numerical
models of NEMOS were: bathymetric data, the port of Alexandroupolis, relative wave timeseries in deep water conditions which are application results of the model WAM performed for the Aegean Sea by H.C.M.R., and past and contemporary shorelines of the area which were produced by processing satellite images and field measurements. The extracted shorelines were used as reference shorelines in the sensitivity tests and the calibration of NEMOS models. The simulation results, show the parts of the study area which are under erosion and those which are under accretion.
Toxicological & Environmental Chemistry, Jan 1, 1989
ABSTRACT The basic objective of this study is the understanding of the hydrology and hydraulic ch... more ABSTRACT The basic objective of this study is the understanding of the hydrology and hydraulic characteristics of Lake Vistonis, a very shallow lake in Northern Greece, connected to the Aegean Sea through an irregular shallow channel. In this paper we estimate the pollutant residence time and the discharge of lake to the Aegean Sea as a function of lake elevation. Also we determine the seasonal variations of salinity of the lake.
The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-G... more The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-Greece-Turkey) river Evros/Maritza has increased dramatically in the last 13 years. It is not clear if the increase of flood frequency is due to climatic changes or to inappropriate management of Bulgarian dams. This fact raises the question of modeling the flood routing through the many dams in the Bulgarian territory (upstream), which receive the runoff of the 38% of the area of the Evros watershed in Bulgaria, in a way to protect the downstream countries from flooding. The basic objective of this paper is the development of a new management tool (software) for the simulation of the rainfall-runoff and routing process taking into account the existence of many dams and mainly their operation not only from a hydrologic viewpoint, but also from the administrative, with emphasis on the "energy-economic" exploitation of the reservoirs. The developed software (named Evrofloods) models the rainfall-runoff, the routing of runoff through the various Evros river tributaries taking in account various scenarios of the runoff through the artificial reservoirs with the aim of optimal management of the water released from the dams spillways and turbines. The "optimal management" is related with the finding for a given rainfall distribution, the appropriate combination of actions at many reservoirs ("reservoirs management") in order to prevent or mitigate the floods downstream, aiming at the same time to minimize hydroelectric energy loss. Although Evrofloods software is basically dedicated to the large Evros basin, it can be easily used to determine the management of large transboundary rivers with many artificial reservoirs to avoid floods downstream. Recent European legislation on floods encourages the good cooperation of neighbor countries, to avoid floods.
Virtual Water is a recently introduced and widely recognized concept that is considered important... more Virtual Water is a recently introduced and widely recognized concept that is considered important for attaining regional and global water security. It refers to the water needed for the production of an agricultural or industrial product and it is contained in the product not in real but in virtual sense. The practical importance of the virtual water concept is mainly twofold, as virtual water trade can act as a tool to achieve water security and efficient water use, while water footprints can act as links between consumption patterns and the impacts on water. This paper applies the virtual water concept at regional level using the Prefectures of Xanthi and Rhodope as case studies. The ensuing results are juxtaposed and commented.
The scope of the present study was to predict the shoreline change in the wider area of the Port ... more The scope of the present study was to predict the shoreline change in the wider area of the Port of Alexandroupolis, forty years from today. In order to achieve our goal, we used the commercial software package CEDAS (Coastal Engineering Design and Analysis System) and in particular, the numerical models of NEMOS (NEMOS is a part of CEDAS software). The most important input data (referring to the study area) for the numerical models of NEMOS were: bathymetric data, the port of Alexandroupolis, relative wave timeseries in deep water conditions which are application results of the model WAM performed for the Aegean Sea by H.C.M.R., and past and contemporary shorelines of the area which were produced by processing satellite images and field measurements. The extracted shorelines were used as reference shorelines in the sensitivity tests and the calibration of NEMOS models. The simulation results, show the parts of the study area which are under erosion and those which are under accretion.
The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-G... more The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-Greece-Turkey) river Evros/Maritza has increased dramatically in the last 13 years. It is not clear if the increase of flood frequency is due to climatic changes or to inappropriate management of Bulgarian dams. This fact raises the question of modeling the flood routing through the many dams in the Bulgarian territory (upstream), which receive the runoff of the 38% of the area of the Evros watershed in Bulgaria, in a way to protect the downstream countries from flooding. The basic objective of this paper is the development of a new management tool (software) for the simulation of the rainfall-runoff and routing process taking into account the existence of many dams and mainly their operation not only from a hydrologic viewpoint, but also from the administrative, with emphasis on the "energy-economic" exploitation of the reservoirs. The developed software (named Evrofloods) models the rainfall-runoff, the routing of runoff through the various Evros river tributaries taking in account various scenarios of the runoff through the artificial reservoirs with the aim of optimal management of the water released from the dams spillways and turbines. The "optimal management" is related with the finding for a given rainfall distribution, the appropriate combination of actions at many reservoirs ("reservoirs management") in order to prevent or mitigate the floods downstream, aiming at the same time to minimize hydroelectric energy loss. Although Evrofloods software is basically dedicated to the large Evros basin, it can be easily used to determine the management of large transboundary rivers with many artificial reservoirs to avoid floods downstream. Recent European legislation on floods encourages the good cooperation of neighbor countries, to avoid floods.
The coastal zone is a transitory zone between land and sea. Due to its importance to man, not onl... more The coastal zone is a transitory zone between land and sea. Due to its importance to man, not only for its high food production but also for recreation, sea transportation and industrial activities, coastal zone receives high environmental pressure from him. This paper deals with degradation phenomena of the coastal zone in the west section of the River Nestos Delta, North Aegean Sea, with special stress on the geomorphological changes in the coastline. The length of the coastline in this part of river Nestos Delta (the Kavala-Chrisoupoli part), from Nea Karvali village to the west, up to the river mouth to the east, is around 35 km long. This section constitutes the biggest and more extended sector of the Nestos Delta; it is the section where the main course and the various branches of the river were located, in the past. Along the coastal zone of this section of the delta many lagoons, sand bars, spits, barrier islands, washover fans, etc. were developed in its geologic past. Some of these geoforms still exist, but the majority of them have been destroyed by physical and/or anthropogenic interventions. Two of the last interventions are the diversion and entrenchment of the river to the east, in early 50's and the construction of two high dams in the river course inland, in 2000. These human interventions deprived this land of flooding waters and sediments resulting in: (a) drying of most of the river channels and courses crossing this area of the river's delta, (b) erosion of the coastal landforms and retreat of the shoreline in the majority of the delta coasts. There are, of course, a few places along the coastline where deposition and accretion are still taking place. In more detail, along the coastline taken into consideration in the present paper, one can meet: • stretches with high erosion rates, like the Akroneri Cape (spit), the inner coastline of Keramoti bay (Kokala-Piges coast), the Monastiraki coastline, etc, • stretches with high accretion rates like the Keramoti peninsula/spit, and • stretches at equilibrium or low rate of change like the barrier (spit) west of Akroneri Cape up to Nea Karvali coast and a short stretch of the coastline southeast of Keramoti peninsula. Comparing the Delta coastline of 1945 (from available aerial photographs) and the coastline of 2002 (from high resolution satellite images), before the construction of the Thisavros and Platanovrisi high dams (period 1945-2002), it has been estimated that: 88% of the delta and the adjacent coastlines has been accreted while only 12% has been eroded. In other words, there was a surplus of accretion by 76% and the delta was procreated. Comparing the Delta coastline of 2002 (from high resolution satellite images) and the coastline of 2007 (from high resolution D-GPS field measurements), after the construction of the dams (period 2002-2007), it has been estimated that: only 39% of the delta and the adjacent coastlines has been accreted while 61% has been eroded. In other words, there was a surplus of erosion by 22% and the delta began to retreat.
We consider the problem of the vertically upwards disposal of heavy brine sewage from a two-dimen... more We consider the problem of the vertically upwards disposal of heavy brine sewage from a two-dimensional diffuser in a lighter, homogeneous, motionless and shallow ambient sea. The rejected high salinity water of seawater desalination plants for urban and agricultural uses is such a case of a two dimensional fountain. The disposal of brine sewage produces a negative buoyant jet due to its initial momentum, which impinges on the free surface, spreads laterally on it and then sinks downwards, because of the negative buoyancy. Laboratory experiments and dimensional considerations are used in this paper in order to investigate the spreading behavior (width) of the vertical fountain which impinges on the free surface of the shallow ambient fluid. The experimental results have been used to derive an equation relating the width at the free surface with the initial parameters of the flow. In addition, the experimentally measured dilution of the heavier brine sewage on the recipient’s surface is compared with the dilution which was calculated by a numerical simulation of a well-known commercial software package, CORJET (a CORMIX sub model).
Computational Water, Energy, and Environmental Engineering
Major flood events occurred in the Arda River region in the last decades with great economic, soc... more Major flood events occurred in the Arda River region in the last decades with great economic, social and environmental effects. A specific software package has been developed for the simulation of the flood runoff and routing process of the transboundary Arda River basin. The software package is taking into account the existence of the three cascade Bulgarian reservoirs aiming to flood protection and power optimization. Inflow estimations for duration of five days ahead and initial water levels at the three reservoirs are imported at the beginning of the simulation. The management tool includes all the alternative operation modes of hydropower plants, water released from spillways, and river and reservoir flow characteristics in order to optimize the total system (power generation and flooding costs) during the flood event. The developed software is also an efficient tool for the establishment of a flood warning system.
4th National Conference “Management and Improvement of Coastal Zones”, Sep 2008
The scope of the present study was to predict the shoreline change in the wider area of the Port ... more The scope of the present study was to predict the shoreline change in the wider area of the Port of Alexandroupolis, forty years from today. In order to achieve our goal, we used the commercial software package CEDAS (Coastal Engineering Design and Analysis System) and in particular, the numerical models of NEMOS (NEMOS is a part of CEDAS software). The most important input data (referring to the study area) for the numerical
models of NEMOS were: bathymetric data, the port of Alexandroupolis, relative wave timeseries in deep water conditions which are application results of the model WAM performed for the Aegean Sea by H.C.M.R., and past and contemporary shorelines of the area which were produced by processing satellite images and field measurements. The extracted shorelines were used as reference shorelines in the sensitivity tests and the calibration of NEMOS models. The simulation results, show the parts of the study area which are under erosion and those which are under accretion.
Toxicological & Environmental Chemistry, Jan 1, 1989
ABSTRACT The basic objective of this study is the understanding of the hydrology and hydraulic ch... more ABSTRACT The basic objective of this study is the understanding of the hydrology and hydraulic characteristics of Lake Vistonis, a very shallow lake in Northern Greece, connected to the Aegean Sea through an irregular shallow channel. In this paper we estimate the pollutant residence time and the discharge of lake to the Aegean Sea as a function of lake elevation. Also we determine the seasonal variations of salinity of the lake.
The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-G... more The flood frequency and the dikes overtopping at the downstream part of transboundary (Bulgaria-Greece-Turkey) river Evros/Maritza has increased dramatically in the last 13 years. It is not clear if the increase of flood frequency is due to climatic changes or to inappropriate management of Bulgarian dams. This fact raises the question of modeling the flood routing through the many dams in the Bulgarian territory (upstream), which receive the runoff of the 38% of the area of the Evros watershed in Bulgaria, in a way to protect the downstream countries from flooding. The basic objective of this paper is the development of a new management tool (software) for the simulation of the rainfall-runoff and routing process taking into account the existence of many dams and mainly their operation not only from a hydrologic viewpoint, but also from the administrative, with emphasis on the "energy-economic" exploitation of the reservoirs. The developed software (named Evrofloods) models the rainfall-runoff, the routing of runoff through the various Evros river tributaries taking in account various scenarios of the runoff through the artificial reservoirs with the aim of optimal management of the water released from the dams spillways and turbines. The "optimal management" is related with the finding for a given rainfall distribution, the appropriate combination of actions at many reservoirs ("reservoirs management") in order to prevent or mitigate the floods downstream, aiming at the same time to minimize hydroelectric energy loss. Although Evrofloods software is basically dedicated to the large Evros basin, it can be easily used to determine the management of large transboundary rivers with many artificial reservoirs to avoid floods downstream. Recent European legislation on floods encourages the good cooperation of neighbor countries, to avoid floods.
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Papers by NIKOS KOTSOVINOS
models of NEMOS were: bathymetric data, the port of Alexandroupolis, relative wave timeseries in deep water conditions which are application results of the model WAM performed for the Aegean Sea by H.C.M.R., and past and contemporary shorelines of the area which were produced by processing satellite images and field measurements. The extracted shorelines were used as reference shorelines in the sensitivity tests and the calibration of NEMOS models. The simulation results, show the parts of the study area which are under erosion and those which are under accretion.
models of NEMOS were: bathymetric data, the port of Alexandroupolis, relative wave timeseries in deep water conditions which are application results of the model WAM performed for the Aegean Sea by H.C.M.R., and past and contemporary shorelines of the area which were produced by processing satellite images and field measurements. The extracted shorelines were used as reference shorelines in the sensitivity tests and the calibration of NEMOS models. The simulation results, show the parts of the study area which are under erosion and those which are under accretion.