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Groundwater is a primary source of drinking water; however, groundwater depletion constitutes a common phenomenon worldwide. The present research aims to quantify groundwater depletion in three aquifers in Greece, including the porous aquifers in the Eastern Thermaikos Gulf, Mouriki, and the Marathonas basin. The hypothesis is to reverse the phenomenon by adopting an environmentally acceptable methodology. The core of the suggested methodology was the simulation of groundwater using MODFLOW-NWT and the application of managed aquifer recharge (MAR) by using water from small dams after the generation of hydropower. Surface run-off and groundwater recharge values were obtained from the ArcSWAT simulation. The predicted future climatic data were obtained from the Coordinated Regional Climate Downscaling Experiment (CORDEX), considering the Representative Concentration Pathway (RCP) 4.5 and the climate model REMO2009. Groundwater flow simulations from 2010 to 2020 determined the existing status of the aquifers. The simulation was extended to the year 2030 to forecast the groundwater regime. In all three sites, groundwater depletion occurred in 2020, while the phenomenon will be exacerbated in 2030, as depicted in the GIS maps. During 2020, the depletion zones extended 11%, 28%, and 23% of the aquifers in Mouriki, the Eastern Thermaikos Gulf, and the Marathonas basin, respectively. During 2030, the depletion zones will increase to 50%, 42%, and 44% of the aquifers in Mouriki, the Eastern Thermaikos Gulf, and the Marathonas basin, respectively. The simulation was extended to 2040 by applying MAR with the water from the existing dams as well as from additional dams. In all sites, the application of MAR contributed to the reversal of groundwater depletion, with a significant amount of hydropower generated. Until 2040, the application of MAR will reduce the depletion zones to 0.5%, 9%, and 12% of the aquifers in Mouriki, the Eastern Thermaikos Gulf, and the Marathonas basin, respectively. Apart from over-pumping, climatic factors such as long periods of drought have exacerbated groundwater depletion. The transformation of dams to mini-scale hydropower facilities combined with MAR will benefit clean energy production, save CO2 emissions, and lead to an economically feasible strategy against groundwater depletion. [ABSTRACT FROM AUTHOR]

This paper presents the investigation of groundwater vulnerability to seawater intrusion of the aquifer system in the coastal area of Laspias River, NE Greece, for the year 2023, by applying the GALDIT, SITE and SIVI methods, in the context of the groundwater management of the area. The relevant research works include the collection and analysis of data and information regarding the geological and geomorphological environment, as well as the hydrogeological system of the area. The calculation of the GALDIT, SITE and SIVI indices values is described, and the results from the application of the methods are presented, as well as the design of relevant groundwater vulnerability maps of the study area. This paper concludes with findings and proposals useful for the reliable assessment of the hydrogeological regime of the wider study area. [ABSTRACT FROM AUTHOR]

Bottom-up management in a catchment scale is deemed the optimal way to avoid conflicts among water users through the participation of stakeholders, strategy co-shaping, and solutions co-creation. Water management cannot be one-dimensional; it demands cross sectoral cooperation. Usually, the difficulty lies in proper stakeholder training and inclusion of their opinions, which should be used in a quantifiable manner in water management. The Laspias River watershed occupies an area of 221.8 km2 that includes the River Basin District of Thrace; it is characterized by intense agricultural and industrial activity. To comply with the augmented water needs and pollution loads this research aims to utilize a hybrid intuitionistic fuzzy multi-criteria-based methodology to address respectfully stakeholders' opinion, this research aims to utilize a hybrid intuitionistic fuzzy multi-criteria-based methodology. It is often difficult to manage planning water management measures as the problems include multiple (conflicting) criteria that are based on stakeholder's opinions, which are usually imprecise and in a rather qualitative form. This study provides the mathematical tools to reach comprehensive decisions with the public involvement offering a practical solution in an existing problem, that is the proper inclusion of stakeholders' opinion. The weights are produced based on a stakeholder's opinion. The alternatives' ranking is achieved based on the fuzzified intuitionistic version of the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), and a hierarchy of mitigation problems is achieved via this novel approach. [ABSTRACT FROM AUTHOR]

Background: Microcystins are emerging marine biotoxins, produced by potentially toxic cyanobacteria. Their presence has been reported in aquatic animals in Greek freshwater, while data are few in marine environments. Since the climate change induces eutrophication and harmful algal blooms in coastal marine ecosystems affecting the public health, further research on microcystins' presence in marine waters is required. The aim of this study was to examine the potential presence of microcystins in mussels Mytilus galloprovincialis in the largest farming areas in Thermaikos gulf, in Northern Greece, and to investigate their temporal and spatial distribution, adding to the knowledge of microcystins presence in Greek Mediterranean mussels. Results: A 4-year microcystins' assessment was conducted from 2013 to 2016, in farmed Mediterranean mussels M. galloprovincialis, in five sampling areas in Thermaikos gulf, in northern Greece, where the 90% of the Greek mussels' farming activities is located. The isolation of potentially toxic cyanobacteria was confirmed by molecular methods. An initial screening was performed with a qualitative and quantitative direct monoclonal (DM) ELISA and results above 1 ng g−1 were confirmed for the occurrence of the most common microcystins-RR, -LR and -YR, by Ultra High Performance Liquid Chromatography (UHPLC) coupled with a high- resolution mass spectrometer (HRMS) (Orbitrap analyzer). Microcystin-RR and microcystin-LR were detected, while the intensity of microcystin-YR was below the method detection limit. Most samples that exhibited concentrations above 1 ng g-1 were detected during the warm seasons of the year and especially in spring. Results indicated an overestimation of the ELISA method, since concentrations ranged between 0.70 ± 0.15 ng g−1 and 53.90 ± 3.18 ng g−1, while the confirmation denoted that the levels of microcystins were 6 to 22 times lower. Conclusions: Microcystin-RR and microcystin-LR were detected for the first time in mussel M. galloprovincialis, harvested from farms in Thermaikos gulf, in Central Macedonia, Greece. Their presence was linked to potentially toxic cyanobacteria. Bioaccumulation was observed in digestive gland, while the concentrations in muscles were found extremely low. Samples with levels above 1 ng g−1 were observed mostly during spring, confirming the seasonal distribution of microcystins. The comparison of the results by the ELISA and the LC-Orbitrap MS method indicated an overestimation of concentration by the ELISA method. [ABSTRACT FROM AUTHOR]

In this work, a hybrid fuzzy-probabilistic approach is proposed in order to classify the hydrological drought. The analysis focuses on the annual cumulative discharge which is considered to be a random variable. Based on a fuzzified version of the frequency factor method, the fitting between the empirical probabilities and the theoretical probability distribution is investigated with the assumption of Log-Normal and Log-Pearson III. This fitting is achieved by using Tanaka's fuzzy linear regression and hence, all the observed probabilities are included within the produced fuzzy band. Furthermore, a modified fuzzy regression model is also applied. An assumption of the mean value and the standard deviation regarding the log-transformed data can be simultaneously achieved based on the theoretical density probabilities and the sample. Based on the achieved fuzzy frequency factor curve, the fuzzy cumulative annual discharge which corresponds to each threshold of drought can be determined. In order to classify the intensity of hydrological drought, an ascending procedure is proposed by comparing the existing annual cumulative discharge and the fuzzified thresholds of the drought categories. The proposed methodology is applied in the case of the Evros River. [ABSTRACT FROM AUTHOR]

In this study, the non-parametric data envelopment analysis was applied in a sample of 66 mussel aquaculture farms for the estimation of the level of technical efficiency. The differences in this estimated level of efficiency were investigated through the application of a Tobit regression model and a technical and economic descriptive analysis provided an indicative picture of the structure and the economic performance of the efficient farms. The results indicated significant inefficiencies in the utilization of the existing production technology. The estimated mean technical efficiency was 0.761, indicating that the mussel farms could increase their production by 23% given the level of inputs. Moreover, the results of the Tobit regression model showed that socio-demographic variables, such as farmer's age, experience in aquaculture, vocational training, and level of education, can partly explain the efficiency differentials. The technical and economic analysis showed that the efficient mussel farms compared to the inefficient farms are larger in size, use less labor per hectare of sea area, and achieve higher net profit. [ABSTRACT FROM AUTHOR]

The article investigates the potential use of frozen mussel (Mytilus galloprovincialis) and mussel meal in the diet of marine fishes sea bass (Dicentrarchus labrax Linnaeus) and sea bream (Sparus aurata Linnaeus). It examines the effect of the dietary inclusion of mussels on the growth of the fingerlings. It concludes that dietary inclusion of mussels can improve the color and quality of the fish due to the presence of carotenoids and also increases the protein efficiency of commercial feeds.

The variable domain 1 (VD1) domain of the control region and a small segment of the rrnaL gene of the F mtDNA type were sequenced and analyzed in 174 specimens of Mytilus galloprovincialis. Samples were collected from eight locations in four Central-Eastern (CE) Mediterranean countries (Italy, Croatia, Greece and Turkey). A new primer, specific for the F mtDNA type, was designed for the sequencing procedure. In total 40 different haplotypes were recorded, 24 of which were unique. Aside from the two populations situated in Thermaikos gulf (Northern Aegean, Greece), relatively high levels of haplotype and nucleotide diversity were estimated for both Central and Eastern Mediterranean populations. Eight out of the 40 haplotypes were shared by at least three populations while two of them were found in all populations. FST and cluster analysis revealed lack of structuring among CE Mediterranean populations with the exception of those located at the Sea of Marmara and Croatian coast which were highly differentiated. Apart from the species' inherit dispersal ability, anthropogenic activities, such as the repeated translocations of mussel spat, seem to have played an important role in shaping the current genetic population structure of CE M. galloprovincialis mussels [ABSTRACT FROM AUTHOR]

The management of complex water problems is nowadays being practised through new ways and approaches. Therefore, water engineers, planners and managers should be appropriately educated through modern undergraduate curricula and by well-designed postgraduate specialisation programmes. Within this framework, a study of the specific characteristics of an ensemble of 14 postgraduate programmes in various fields of environmental water resources engineering and management, offered by Greek universities, is presented. Detailed information and data regarding the formats, structures, educational processes and curricula contents of these programmes are analysed and critically discussed. Similarities and differences among them are depicted and synthesised, in order to reveal individual as well as collective qualities and deficiencies in relation with the overall current needs for engineering postgraduate specialisation in water-related issues. [ABSTRACT FROM PUBLISHER]

An effective anesthetic scheme would significantly contribute to the investigation of disease in the Mediterranean mussel (Mytilus galloprovincialis), especially when biopsy is required. In this study, we evaluated the efficacy of six anesthetics: 2-phenoxyethanol (2 ml/l), MS222 (0.4 and 1 g/l), MgCl2 (20 and 50 g/l), clove oil (1.5 ml/l), benzocaine (1.5 g/l), and 1-phenoxy-2-propanol (2.5 ml/l) when used to anesthetize Mediterranean mussel. For this purpose, 810 mussels were allocated to nine groups of 90 mussels each (three replicates of 30 individuals in each group). Each group was exposed to one of the above concentrations of anesthetics for 24 h, except for one group kept as the control. Mussels were considered anesthetized when they did not close their valves after tapping them with a pair of forceps. The most effective anesthesia was MS222 at the concentration of 1 g/l; it induced anesthesia in 58.8±1.92% of the exposed mussels with negligible mortality (5.7±5.8%) of the anesthetized mussels one week after anesthesia. Further, when using MS222 there was no correlation between the number of anesthetized mussels and temperature. However, the number significantly increased as the size of the mussels decreased. MgCl2 at the concentration of 20 g/l resulted in notable retardation of valve movement. [ABSTRACT FROM AUTHOR]

The Standardized Precipitation Index (SPI) is widely used as drought meteorological index, to identify the duration and/or severity of a drought. The SPI is usually computed by fitting the gamma probability distribution to the observed precipitation data. In this work, the possibility to calculate SPI by fitting to the precipitation data the normal and the log-normal probability distributions was studied. For this purpose, 19 time series of monthly precipitation of 76 years were used, and the assumption that the gamma probability distribution would provide better representation of the precipitation data than log-normal and normal distributions, at various time scales (1, 3, 6, 12 and 24 months) was tested. It is concluded that for SPI of 12 or 24 months, the log-normal or the normal probability distribution can be used for simplicity, instead of gamma, producing almost the same results. [ABSTRACT FROM AUTHOR]

Shellfish farming often takes place in areas subjected to various recurring pollutions. The intensive use of herbicides in agriculture leads to the presence of residues in the aquatic ecosystems. In the present study, the effects of atrazine on the viability of the mussel Mytilus galloprovincialis and the formation of their byssus were studied. A total of 720 mussels (mean length 24 mm ± 2.1 SD) were divided into six groups. The mussels from the first five groups were exposed to five concentrations of atrazine, 10, 8, 5, 2 and 1 ppm, while one group was used as control. The LC was calculated after 48 h, while the long-term effect of atrazine on the viability and byssus formation of the mussels were studied for 21 days. The LC was found to be 6.33 ppm. From all the concentrations of atrazine to which the mussels were exposed, only in two of them (2 and 1 ppm) some mussels survived up to the last day of the experiment. The survival rate in the control group was significantly higher than those of mussels that were exposed to atrazine. Regarding the byssus formation, the number of byssal threads was significant lower in the mussels that were exposed to 2 and 1 ppm atrazine compared to the control group, while no byssal threads were formed by the mussels exposed to 10, 8 and 5 ppm. All the mussels that survived on day 21 were then exposed to air. The LT for the control group and the mussels which had been exposed to 1 and 2 ppm atrazine were 5.14, 2.77 and 1.98 days, respectively. The results of the present study indicate that atrazine has a significant effect on the viability of mussels both in the water and in air and on their ability to form byssus. [ABSTRACT FROM AUTHOR]

During floods, the density of river water usually increases due to a subsequent increase in the concentration of the suspended sediment that the river carries, causing the river to plunge underneath the free surface of a receiving water basin and form a turbidity current that continues to flow along the bottom. The study and understanding of such complex phenomena is of great importance, as they constitute one of the major mechanisms for suspended sediment transport from rivers into oceans, lakes or reservoirs. Unlike most of the previous numerical investigations on turbidity currents, in this paper, a 3D numerical model that simulates the dynamics and flow structure of turbidity currents, through a multiphase flow approach is proposed, using the commercial CFD code FLUENT. A series of numerical simulations that reproduce particular published laboratory flows are presented. The detailed qualitative and quantitative comparison of numerical with laboratory results indicates that apart from the global flow structure, the proposed numerical approach efficiently predicts various important aspects of turbidity current flows, such as the effect of suspended sediment mixture composition in the temporal and spatial evolution of the simulated currents, the interaction of turbidity currents with loose sediment bottom layers and the formation of internal hydraulic jumps. Furthermore, various extreme cases among the numerical runs considered are further analyzed, in order to identify the importance of various controlling flow parameters. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The constantly growing human needs for water aiming to supply urban areas or for energy production or irrigation purposes enforces the application of practices leading to its saving. The construction of dams has been continuously increasing in recent years, aiming at the collection and storage of water in the formed reservoirs. The greatest challenge that reservoirs face during their lifetime is the sedimentation caused by debris and by the effects of climate change on water harvesting. The paper presents an investigation on the amount, the position and the height of the debris ending up at the Nipsa reservoir. The assessment of the debris volume produced in the drainage basin was conducted by a geographical information system (GIS) based model, named TopRunDF, also used to predict the sedimentation area and the sediment deposition height in the sedimentation cone. The impact of climate change to the reservoir storage capacity is evaluated with the use of a water balance model triggered by the HadCM2, ECHAM4, CSIRO-MK2, CGCM1, CCSR-98 climate change models. The results predict a significant future decrease in the stored water volume of the reservoir, and therefore several recommendations are proposed for the proper future functioning and operation of the reservoir. [ABSTRACT FROM AUTHOR]