Konstantinos Voudouris
Aristotle University of Thessaloniki, Geology, Faculty Member
Nitrate pollution of surface and groundwater resources is a major worldwide environmental problem. In this study nitrogen isotopes of water, soil, fertilizer and manure were analyzed to determine the pollution sources of nitrate in the... more
Nitrate pollution of surface and groundwater resources is a major worldwide environmental problem. In this study nitrogen isotopes of water, soil, fertilizer and manure were analyzed to determine the pollution sources of nitrate in the groundwater and surface waters of Anthemountas basin. The SIAR model and multivariate statistical analysis were used to determine and quantify the contribution of different NO 3̄s ources in groundwater and surface water. Additionally, a detailed literature overview was carried out to identify the origin of nitrate pollution in surface and ground waters based on ΝΟ 3 − isotopes. The Piper diagram identified the dominant water types as Mg-Ca-HCO 3 and Ca-Mg-HCO 3. Nitrate concentrations reached 162.0 mg/L in groundwater and 39.0 mg/L in surface waters. The main source of nitrate in groundwater was mainly nitrified ammonium-based synthetic urea and less nitrate-based synthetic fertilizers. The correlation of SIAR results with other trace elements revealed a negative correlation between hexavalent chromium and a) nitrate-based synthetic fertilizers, and b) nitrification of urea synthetic fertilizers. However, a positive correlation was observed between hexavalent chromium and anthropogenic organic matter. The literature overview provided the basis to design a novel management protocol for nitrate pollution that includes three steps: a) fundamental research, b) management tools, c) monitoring and preservation actions. However, an integrated management protocol for nitrate pollution requires a deeper understanding of the hydro-system and the full participation of local farmers and stakeholders.
Human activities are deeply connected with groundwater reservoirs, so protecting them from pollution has become a priority in many regions of the world. Nitrate is considered the main groundwater pollutant since it is directly linked to... more
Human activities are deeply connected with groundwater reservoirs, so protecting them from pollution has become a priority in many regions of the world. Nitrate is considered the main groundwater pollutant since it is directly linked to many human activities. Agricultural activities and domestic wastewater have been identified as the main sources of nitrate in groundwater. Nevertheless, there are some natural processes that can mitigate nitrate pollution. Together with dilution processes, the degradation of nitrate through denitrification has been acknowledge as a process that can potentially reduce nitrogen loads, in both deep and shallow aquifers. Usually these processes were not properly quantified in vulnerability assessment methods, until the introduction of LOS indices. In this study, the application of the LOS indices on 4 agricultural areas is discussed, highlighting how the LOS indices can identify portions of the landscape with higher potential denitrification and how they directly enhance the groundwater vulnerability assessment. Previous studies have shown that LOS indices are a valuable tool for proper vulnerability assessment to nitrate, however they need to be coupled with other parameters that also describe nitrate behavior in groundwater. The SINTACS-SVN and DRASTIC-PA methods that include the LOS indices, were applied for the first time in the Epanomi coastal area to evaluate the reliably of the assessment and, despite the different classes range and the weights applied, similar groundwater vulnerability assessment maps were obtained. The nitrate vulnerability maps were comparable with the observed nitrate concentrations and were found to be highly comparable with original LOS maps. Nevertheless, it should be kept in mind that vulnerability methods are only screening tools and groundwater quality observations are pivotal information for environmental management.
Advanced, well organized, and operated urban water supply systems existed in Greece from the Bronze Age (ca. 3200-1100 BC). At the dawn of human history, surface water and groundwater, principally springs, were the most common water... more
Advanced, well organized, and operated urban water supply systems existed in Greece from the Bronze Age (ca. 3200-1100 BC). At the dawn of human history, surface water and groundwater, principally springs, were the most common water supply sources. As the population grew, periodic water shortages occurred. In Early Minoan times (ca. 3200-2100 BC), these water shortages led to the development of sophisticated hydraulic structures for importing water and for the harvesting and storage of rainwater. In addition, the water treatment technologies and water distribution techniques developed at that time served as the basis for the advanced technological progress in the development of the urban water supply systems in the centuries that followed. In this paper, an overview of the evolution of public water supplies and water treatment technologies in the Hellenic world through the centuries up to modern times is presented. Some of the most significant innovations in the provision of water, its treatment, and distribution are highlighted. The overview is followed by a discussion of the contemporary situation, emerging trends, and future challenges, and parallels are drawn between historical developments and the water supply problems faced today. Key words | ancient Greece, ancient hydraulic technologies, future trends, modern times, urban water systems, water treatment devices PROLEGOMENA '… the principle of all things is water, out of water is all and into water goes all things back ….' Thales of Miletus (624-546 BC) Modern humans (Homo sapiens) have dwelled on earth for over 200,000 years, originally as hunter-gatherers, and with the population began to expand faster than ever before (Vuorinen et al. ). A new era started about 10,000 years ago when humankind adopted a rural way of living and established permanent small settlements (i.e. villages) scattered over wide areas. Because their settlements were highly dependent on water, a new relationship developed between humans and water (Rose & Angelakis ). When people lived as hunters and/or collectors, river water was used for drinking purposes. Also, the first permanent settlements were usually near a river or lake (e.g. China, Egypt, Mesopotamia). However when settlements were established in areas where there were no rivers or lakes, groundwater sources were used for drinking water purposes. At that time, waterborne diseases became a very serious health risk for the prehistoric agriculturists (Vuorinen et al. ). The earliest known permanent settlement, which can be classified as urban, is Jericho, a city in the Palestinian Territories , located near the Jordan River. There is evidence of a settlement dating back to ca. 10,000 BCE (before the common era or before Christ, BC) (Mithen ). In Greece, the Neolithic settlement of Sesklo, located in northeastern Thessaly, is considered as one of the earlier Neolithic settlements of Europe. It covered an area of approximately 20 ha (1 ha ¼ 10,000 m 2) during its peak period at ca. 5000 BC and comprised about 500-800 773
Floods as diachronic and international phenomena affect numerous people, buildings and infrastructure. Throughout human history, floods are the most lethal and have caused more economic losses than other natural disasters. In this review,... more
Floods as diachronic and international phenomena affect numerous people, buildings and infrastructure. Throughout human history, floods are the most lethal and have caused more economic losses than other natural disasters. In this review, the history of floods is considered focusing in ancient Greece since the early Bronze Age. Ancient Greeks avoided living near lakes and rivers probably for hygiene reasons and protection from floods. Representative impressive hydraulic anti-flooding works including dams, walls, channels from different cities and other settlements in the Minoan era, and the Archaic, Classical, Hellenistic and Roman period are presented. It is concluded that the risk with respect to flood events is more severe today than in ancient times. The ongoing urbanization and deforestation through the centuries have led to an increasing and unmanageable flood risk. For this reason , a set of special measures should be applied in vulnerable areas aiming to mitigate severe damages that floods might cause, including anti-flooding dams, water flow diverting technologies, rainwater harvesting and rain gardens for stormwater retention, reforestation and other smart environmental strategies. The examples of anti-flood hydro-technologies described in this paper may have some relevance for water engineering even in modern times.
Groundwater resources are the main supply of freshwater for human activities. However, in the last fifty years aquifers have become more susceptible to chemical pollution due to human activities. The concept of groundwater vulnerability... more
Groundwater resources are the main supply of freshwater for human activities. However, in the last fifty years aquifers have become more susceptible to chemical pollution due to human activities. The concept of groundwater vulnerability constitutes a worldwide accepted tool for water protection and planning. However, the existing methods and modified versions do not account for all the hydrogeochemical processes that drive anthropogenic pollution. The hydrogeochemical processes occurring within an aquifer can be determined using multivariate statistical analysis. In this study a specific vulnerability method named SVAP (Specific Vulnerability to Anthropogenic Pollution) is proposed. The index is based on seven quantitative parameters: depth to groundwater, recharge, nitrate losses, hydraulic resistance of the vadose zone, aquifer thickness, hydraulic conductivity of the aquifer, and slope. Weights of anthro-pogenic factors were determined by factor analysis and used to validate the SVAP methodology. The parameters' classification was selected according to the highest Pearson's correlation coefficient with factor weights and then grouped via a linear combination. The new index was applied in two watersheds: the Florina basin (Greece) and the Garigliano River basin (Italy), both of which possess complex hydrogeochemical regimes. The main hydrogeochemical processes acting in the study areas were identified via factor analysis, which revealed that the anthropogenic pollution in both sites was due mainly to chemical fertilizers and manure. Verification of the SVAP method produced correlation coefficients with nitrate concentrations of 0.75 and 0.62 in Florina and Garigliano, respectively. The proposed SVAP method is more reliable and flexible than standard vulnerability assessment methods and can be easily adapted for complex aquifers.
The effect of climate change on future groundwater conditions in the Toyserkan basin in western Iran has been studied. In recent years, overexploitation for agricultural activities has led to water-table decline. Groundwater recharge rate... more
The effect of climate change on future groundwater conditions in the Toyserkan basin in western Iran has been studied. In recent years, overexploitation for agricultural activities has led to water-table decline. Groundwater recharge rate predictions in the study area were obtained from the RCP4.5 Scenario of the 5th Assessment Report of the Intergovernmental Panel on Climate Change and HadGEM2 General Circulation Model. Outputs were downscaled with the RegCM4 Regional Climate Model coupled to the Community Land Model version 4.5 (CLM 4.5). RegCM4 model validation and prediction were attempted for 7 years (1999-2005) and 11 years (2015-2025), respectively. Validation results showed that RegCM4 reasonably simulated daily precipitation and monthly temperature and runoff. Firstly, geological, geophysical and hydrogeological data were used and evaluated to develop the conceptual model. Secondly, a 3D numerical model of groundwater flow was developed in order to describe the groundwater regime and predict the effects of water management strategies. Two scenarios were defined for the prediction period. The first scenario assumes that current exploitation rates will be continued, while the second one assumes a 20 percent decrease in pumping due to increased irrigation efficiency. The results showed a water-table rise from 2015 to 2025, which is heightened by increase in irrigation efficiency.
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Shallow aquifers are the most accessible reservoirs of potable groundwater; nevertheless, they are also prone to various sources of pollution and it is usually difficult to distinguish between human and natural sources at the watershed... more
Shallow aquifers are the most accessible reservoirs of potable groundwater; nevertheless, they are also prone to various sources of pollution and it is usually difficult to distinguish between human and natural sources at the watershed scale. The area chosen for this study (the Campania Plain) is characterized by high spatial heterogeneities both in geochemical features and in hydraulic properties. Groundwater mineralization is driven by many processes such as, geothermal activity, weathering of volcanic products and intense human activities. In such a landscape, multivariate statistical analysis has been used to differentiate among the main hydrochemical processes occurring in the area, using three different approaches of factor analysis: (i) major elements, (ii) trace elements, (iii) both major and trace elements. The elaboration of the factor analysis approaches has revealed seven distinct hydrogeochemical processes: i) Salinization (Cl À , Na þ); ii) Carbonate rocks dissolution; iii) Anthropogenic inputs (NO 3 À , SO 4 2À , U, V); iv) Reducing conditions (Fe 2þ , Mn 2þ); v) Heavy metals contamination (Cr and Ni); vi) Geothermal fluids influence (Li þ); and vii) Volcanic products contribution (As, Rb). Results from this study highlight the need to separately apply factor analysis when a large data set of trace elements is available. In fact, the impact of geothermal fluids in the shallow aquifer was identified from the application of the factor analysis using only trace elements. This study also reveals that the factor analysis of major and trace elements can differentiate between anthropogenic and geogenic sources of pollution in intensively exploited aquifers.
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Multivariate statistical analysis has been widely used for hydrogeochemical characterization of groundwater quality. In this study, hydrochemical data from three hydrological basins were used and two methods (factor and cluster analyses)... more
Multivariate statistical analysis has been widely used for hydrogeochemical characterization of groundwater quality. In this study, hydrochemical data from three hydrological basins were used and two methods (factor and cluster analyses) were applied. The first area is the coastal area of Eastern Thermaikos Gulf where groundwater is influenced by seawater intrusion and geothermal fluids. The other two areas are the inland basins of Gallikos and Perdikas in which agricultural and industrial activities constitute the main anthropogenic pollution sources of groundwater. Initially, the aforementioned methods were applied for each area separately and resulted in a different number of significant factors and clusters, while the natural and anthropogenic influences were spatially determined in each area. Additionally, factor and cluster analyses were applied coupling data from all areas. Therefore, five clusters and three major factors were determined distinguishing the hydrochemical processes and impacts from anthro-pogenic activities in more detail. It is worth mentioning that the application of cluster analysis in the coupled groundwater samples of all studied areas resulted beneficially in the most hydrochemically complex area. Salin-ization dominates in the coastal area, while in Gallikos and Perdikas basins high concentrations of NO 3 occur mainly due to agricultural activities and small livestock units. The numerous hydrochemical samples are identified as the main issue for the higher discretization and reliability of the second approach. Nevertheless, this study is associated with a number of limitations of multivariable statistical analysis regarding extreme concentrations of Cl and Na. This issue stimulates further research in overcoming and understanding these drawbacks.
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The aim of this study is to reveal the geological, paleontological and hydrogeological features of the surrounding area of Oinoi in municipality of Kastoria, Northern Greece. These features can attract visitors and develop geotourism in... more
The aim of this study is to reveal the geological, paleontological and hydrogeological features of the surrounding area of Oinoi in municipality of Kastoria, Northern Greece. These features can attract visitors and develop geotourism in the area. Fossil mollusk shells (Pectinidae family, Pecten and Flabellipecten) were recognized in three fossiliferous sites. Additionally, the palaeontological features are supplemented by impressive alternations of sedimentary strata, cavities, springs, small natural waterfalls and lakes as well as a small dam. Three routes (the longest is 12.3 Km) were defined for the promotion of these features. The routes are suitable for walking, jogging, mountain biking, climbing, for students, elder people and adults. This is a preliminary approach, since further research in the wider area is needed, in order to include more existing natural features, as well as to create a comprehensive management plan and define the criteria for the proposal of the site as a Geopark.
Ground and spring waters, soils and sediments of Anthemountas basin in Northern G reece were analyzed for Potential Toxic Elements (PTEs). In total, twenty three soil and sediment samples, three groundwater (boreholes) and two spring... more
Ground and spring waters, soils and sediments of Anthemountas basin in Northern G reece were analyzed for Potential Toxic Elements (PTEs). In total, twenty three soil and sediment samples, three groundwater (boreholes) and two spring water samples, were analyzed. Contents of Ni in soils and sediments can be as high as 2169 mg/kg. The high correlation coefficient of Ni and Cr, indicates the geogenic origin of Ni, which originates from ophiolitic rocks. Arsenic concentration ranges from 3 to 110 mg/kg in soils and sediments, with the highest contents observed in travertine. The spring waters are characterized by elevated concentrations of As (up to 235 g/L), N a, K, Fe and Zn, indicating that hydrothermal fluids are responsible for feldspar alte ration of the Monopigado granodiorite. On the contrary, in groundwaters, As conten ts are low (up to 18 g/L). Electrical resistivity tomographies performed around the groundwater boreholes, revealed the presence of normal faults, locally allowing the mixing of geothermal fluids with the shallow porous aquifer (SPA). The presence of As in the SPA is probably due to inputs from geothermal waters through normal faulting.
The aim of this study is to evaluate climate model hydrological parameters in comparison to recorded hydrological data and estimate the impacts of climate change on water balance. For this purpose, a combination of climate model... more
The aim of this study is to evaluate climate model hydrological parameters in comparison to recorded hydrological data and estimate the impacts of climate change on water balance. For this purpose, a combination of climate model precipitation and temperature data and Thornthwaite method was applied for the period 1988-2000 and the future periods 2028-2040, 2058-2070 and 2088-2100. The application of this combination was carried out in a coastal region in Southeastern part of Korinthiakos Gulf (southern Greece). The area is suitable for this target, because it is characterized by urbanization, intensive agriculture and tourism development, with increasing water demands. The evaluation of climate model parameters in comparison to observed data shows that the RegCM3 model is a reliable model. According to the future projections and the Thornthwaite method, the real evapotranspiration is estimated to increase, as a result precipitation decrease and temperature increase.
Floods are one of the most common natural hazards in global range and could threat the human life, health, environment and infrastructure. The aim of this paper is the estimation and the delimitation of the likely flood hazard zones, for... more
Floods are one of the most common natural hazards in global range and could threat the human life, health, environment and infrastructure. The aim of this paper is the estimation and the delimitation of the likely flood hazard zones, for different rainfall intensities in the upper part of Gallikos river basin (central Macedonia) according to the European directive 2007/60. For the analysis of the meteorological data and the construction of flood zone maps, HYDROGNOMON, HEC-HMS, HEC-RAS free software packages were used. The thematic maps were constructed with ESRI GIS. The results are depicted in flood inundation maps, delimitating and visualizing the scale of the flood hazard effect in the area. The construction of flood prediction models is a very useful tool towards the direction of the design of an efficient flood management framework.
Malia's coastal aquifer supplies water for domestic and irrigation purposes most of northern part of Heraklion prefecture (central Crete). The extensive exploitation of groundwater since the late 1960s has resulted in a continual decline... more
Malia's coastal aquifer supplies water for domestic and irrigation purposes most of northern part of Heraklion prefecture (central Crete). The extensive exploitation of groundwater since the late 1960s has resulted in a continual decline in groundwater level and significant degradation in groundwater quality, due to salinity intrusion in the coastal aquifer. Moreover, the aquifer will likely to experience impacts of climate-driven recharge changes in the coming years, with adverse consequences for water supply in the region. A regional groundwater flow model was developed to simulate the existing hydrogeological system, and to evaluate the effects of combined impacts of groundwater exploitation and climate variability in future. The investigation results suggest that the equivalent porous medium (EPM) approach appears reasonable for the karst aquifers on a regional scale, as it is capable to simulate the groundwater flow and the spreading of chloride concentration with sufficient accuracy. However, locally the transport of saline water may depend primarily on the karst conduit network rather than matrix permeability; therefore the point information must be evaluated and not taken as undisputed. Furthermore, the study provides a valuable guidance on predicting the seawater intrusion in aquifers under similar hydrogeological conditions; and offers a considerable issue in management of the groundwater quality deterioration.
The eastern part of the Thermaikos Gulf is characterized by urbanization, touristic development and intensive agricultural activities. Water resources are characterized by high water demands for agriculture and tourism during the dry... more
The eastern part of the Thermaikos Gulf is characterized by urbanization, touristic development and intensive agricultural activities. Water resources are characterized by high water demands for agriculture and tourism during the dry period (May-late September) when water availability is low. The main aquifers are within coarse grained Neogene and Quaternary deposits (porous aquifers). This study deals with the impacts of the aforementioned activities on groundwater resources in this area. Therefore, hydrometeorological, hydrogeological and hydrochemical data were collected, evaluated and compared with previous studies. The water demands for domestic and irrigation use are mainly covered by groundwater abstracted from aquifer systems via numerous boreholes. A continuous groundwater level decline has been recorded over the last 30 years and a negative water balance has been established in the coastal aquifer favoring sea water intrusion. The concentration values of chloride range between 400 mg/L and up to 700 mg/L at this area having as a result the degradation of groundwater quality. An additional pressure in the area is the intensified fertilization, as it is documented by the increased nitrate concentration. High nitrate values locally exceed the maximum admissible concentration of 50 mg/L set by EU Council for drinking water therefore rendering most groundwater unsuitable for human consumption. The DPSIR approach (Driver-Pressure-State-Impact-Response) was applied in order to be used as a useful tool for the selection of the most appropriate environmental indicators in order to construct a suitable monitoring network that will help decision makers and stakeholders to take the appropriate measures and to monitor the effectiveness of their implementation. In the present paper measures such as: the reuse of the treated wastewater for irrigation purposes, the construction of dams for exploitation of surface water, artificial recharge, public education, etc. are proposed in order to achieve an integrated and sustainable water resources management.
The magnetic minerals (e.g., iron oxides) that are present in soils can be easily identified by using rock-magnetic techniques. Increased magnetic susceptibility of soils may reflect particles rich in iron oxides of anthro-pogenic,... more
The magnetic minerals (e.g., iron oxides) that are present in soils can be easily identified by using rock-magnetic techniques. Increased magnetic susceptibility of soils may reflect particles rich in iron oxides of anthro-pogenic, lithogenic, and pedogenic origin. Therefore, reliable discrimination of these sources is required, especially in areas where neither of them is dominant. The aim of the present study is to assess the lithogenic and anthropogenic contributions to iron-oxide mineralogy of soils in the area of the Anthemountas River basin in the southeast part of Thessaloniki city. Previous investigations within the study area, based on spatial distribution of magnetic susceptibility , revealed the presence of two magnetically enhanced regions. Therefore, the present study is focused on these two areas, in order to characterize the origin of magnetic enhancement. Detailed magnetic analyses include properties reflecting the type, concentration, and relative grain-size distribution of magnetic particles. Moreover, trace element concentration is determined with an aim to establish the link between low-field mass-specific magnetic susceptibility and concentration of Fe, Cr, Ni, Mn, Pb, Zn, and Ti. These findings are supported by descriptions of the micromorphology performed by scanning electron micro-scopy and determination of elemental composition by energy-dispersive spectrometer analyses in selected points. Finally hierarchical cluster analysis is applied to classify the soil samples into appropriate groups according to their magnetic properties. The results reveal that magnetic measurements provide a useful tool for the discrimination between different magnetic sources responsible for the enhancement of magnetic susceptibility in soils. Low-field mass-specific magnetic susceptibility reflects increased concentration of trace elements, while its combination with other magnetic measurements clearly differentiates the origin of magnetic enhancement in both parts of the study area.
Groundwater has been utilized since the Prehistoric times. Water supply of some Minoan settlements on the eastern side of the island of Crete (Greece) was based on groundwater. Later on, many wells were constructed in several areas of... more
Groundwater has been utilized since the Prehistoric times. Water supply of some Minoan settlements on the eastern side of the island of Crete (Greece) was based on groundwater. Later on, many wells were constructed in several areas of Greece and their use expanded through subsequent periods. The greatest achievement in groundwater exploitation by ancient Greeks was the construction of long underground galleries or qanats, which collected water from springs and alluvial deposits. In Classical times, most of the wells were on private properties and their owners were forced by regulations to maintain the wells in good condition and ready for use in wartime. During that period, the first scientific theories of Aristotle and Theophrastus were developed in regards to hydrological phenomena, and the processes involved in the formation of surface water and groundwater were clarified. Wells played a major part in urban water supply during the Roman period, in which famous aqueducts were constructed to transfer water; however, several regions of Greece were self-sufficient in water, supplied by many wells from the Prehistoric to the Byzantine period. People understood the local geological conditions and, according to their culture, constructed and managed their own types of wells. In addition to the wells and aqueducts, the hydraulic technology included cisterns to store rainwater, and systems to capture spring water for transport by aqueducts. The examples of hydro-technologies and water management practices described in this paper may have some relevance for water engineering even in modern times.
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The alluvial aquifer of the Sarigkiol basin extends NW of Greece, covering an area of 60 km2. In a large part of the area irrigated agriculture is practiced. The aquifer is the main source of water supply in the area and is showing signs... more
The alluvial aquifer of the Sarigkiol basin extends NW of Greece, covering an area of 60 km2. In a large part of the area irrigated agriculture is practiced. The aquifer is the main source of water supply in the area and is showing signs of contamination due to the existence of pollution sources. Regional assessment of groundwater pollution risk is an useful tool for groundwater resource management and protection. Risk assessment is defined as a combination of hazard and vulnerability. The DRASTIC method was applied to evaluate groundwater vulnerability, including the following seven parameters: Depth, Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone and hydraulic Conductivity. Determination of the DRASTIC index involves multiplying each parameter weight by its site rating and summing the total. Based on DRASTIC index values a groundwater vulnerability map was illustrated, using a Geographical Information System (GIS). The higher index values represent greater potential for groundwater pollution, or greater aquifer vulnerability. In order to evaluate the degree of hazard the land use map was used. A groundwater pollution risk map was created by overlaying the vulnerability map with the hazard map. The results provide important information and the pollution risk map could be used from local authorities and decision makers for groundwater resources management and protection zoning.
The purpose of this study is to present a robust methodology that can provide an accurate and reliable estimation of the lateral mobility and vertical scour at the crossing points of a pipeline with rivers/torrents. A new protocol is... more
The purpose of this study is to present a robust methodology that can provide an accurate and reliable estimation of the lateral mobility and vertical scour at the crossing points of a pipeline with rivers/torrents. A new protocol is proposed, which includes detailed description of the different steps of a proper hydrologic and hydraulic study at the areas of the crossing points. The rate and extent of the lateral movement of a river channel is controlled by the river discharge and the sediment load for a specific forecasting time period. The assessment of the lateral movement is based on field observations and analysis of Google Earth and satellite images. In order to assess the lateral mobility risk, a rating method was developed, which takes into account the following factors: Sediment load, Riparian vegetation, Type of Channel, Flow velocity and discharge, Civil works and Floodplain. Scour (vertical erosion) is the removal of material from the bed and banks of a channel, due to the physical action of flowing water, as well as to human activities. The total vertical scour depends on hydrological and geomorphological procedures, civil works, (constriction scour) climate change and human intervention. The aforementioned parameters are specified in the proposed methodology. The general scour was estimated by using different empirical methodologies, e.g. Blench, Lacey and Alvarez-Alfaro, which are widely used, according to the scientific literature. Finally, two indicative case studies from North Greece are presented.
Chloride concentration and salinity tend to vary spatially in depth within the unsaturated zone, according to the local hydrologic conditions; and therefore are widely used as naturally occurring environmental tracers. In this study,... more
Chloride concentration and salinity tend to vary spatially in depth within the unsaturated zone, according to the local hydrologic conditions; and therefore are widely used as naturally occurring environmental tracers. In this study, undisturbed material from the unsaturated zone was collected at regular intervals of 50 cm down to a maximum depth of 300 cm in 17 different locations. Vacuum filtration has been used for extraction of soil water from 75 soil samples, and chemical analyses showed that the chloride concentrations in soils range from 0.4 to 79 meq/L indicating the existence of soluble salts, also verified by elevated electrical conductivity values.
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ABSRACT: The provision of water has been a major enterprise in human history. Groundwater has been utilized since the Prehistoric times to cover the human needs. Initially, the exploitation of groundwater has been made by shallow wells... more
ABSRACT: The provision of water has been a major enterprise in human history. Groundwater has been utilized since the Prehistoric times to cover the human needs. Initially, the exploitation of groundwater has been made by shallow wells and later by boreholes. A water well is an excavation in the ground by digging, driving, boring, or drilling to access groundwater in aquifers. Groundwater wells were used in Helladic world since Neolithic times. Ancient Chinese also developed a drilling tool for water wells which, in principle, is similar to modern machines. Moreover, the Indus valley civilization had well-constructed wells mainly for drinking purposes. The construction of wells varied according to local conditions, determined by geology, hydrogeology, morphology, as well as to the local tradition. Furthermore, a well was not just a water source but also became a cultural symbol on the history, related to local religion and custom. For example, the stepwells in India became not only sources of drinking water, but cool sanctuaries for bathing, prayer, and meditation. In the present review the evolution of wells through the centuries is examined. The examples of water wells technologies demonstrate that the ancient people had an outstanding engineering knowledge of water supply, which is interesting for water engineering and hydrogeologists even nowadays.
