Advances in the Research of Aquatic Environment

This study aims to propose a vertical structuring of water production zones for three types of fractured rocks encountered in Ivory Coast, West Africa. In a first step, the methodology consists of the characterization of the weathering profiles based on: i) bedrocks and weathering layers observations at outcrop; ii) interpretation and synthesis of geophysical data and lithologs from different boreholes. In a second step, the evolution with depth of flow rate (air-lift discharge rates) as well as the frequency and the density of water production zones during drilling are statistically analyzed. Then, the distributions of these various properties versus the depth are fitted to probability laws. For each of the geological formations (granites, metasediments and volcanites) the related weathering profile comprises, from top to bottom, four separate layers:

alloterite, isalterite, fissured layer

and

fractured fresh basement

; these weathering profiles are systematically covered by a soil layer. In granites, the maximal values of flow, frequency and density of the water production zones (WPZ) are situated around 40 m depth systematically within the

fractured fresh granite layer

. In metasediments and volcanites, the maximal values of flow, as well as the maximal frequency and density of WPZ are identified at two distinct depths. The first WPZ, around 40 m depth, is associated to the

fissured layer

for both profiles; the second WPZ, around 80 m depth is associated to the

fractured fresh sandstone layer

for the weathering profile in metasediments and to the

fractured fresh metabasalt layer

, for the weathering profile in volcanites.

The movement and storage of ground water in the mountainous region has a significant impact on the dynamics of surface water flow. An adequate identification of the conductible fracture in the aquifer has thus received growing interest over the past decades. This paper summarizes the major findings from the first year of a hydrogeological investigation program initiated by the Central Geological Survey, Ministry of Economic Affairs (MOEA) of Taiwan since 2010, with a special focus on exploring in detail the fracture permeability. During the on-site investigation, geophysical logging was applied to delineate the lithostratigraphic characteristics of bedrock aquifers. The hydraulic conductivity of 67 observation segments was estimated by the constant head injection method. From the information gathered in this study, the hydraulic conductivities of the identified fractured medium above a depth of 40m are more than one order higher than that of the matrix. The occurrence of ground water in a fracture network, however, is found to be not solely governed by lithological composition, but more possibly by fracture porosity and spacing. A simple linear relationship was found by plotting the hydraulic conductivity against the product of total porosity and cubic aperture ratio (fracture spacing/sealed-off interval between the packers).

The Wajid Sandstone is one of the most important groundwater reservoirs in the Kingdom of Saudi Arabia. The knowledge of the dimensions and the distribution of its sedimentary facies are essential for high quality reservoir interpretation. Hitherto, the facies and their dimensions are only roughly known from extrapolation of subcrop data and geophysical surveys.

Sedimentological logging and correlation of the sections led to an interpretation of the depositional processes and a more detailed facies model. Based on systematic lithofacies and architectural element analysis, the so far established and published facies characteristics derived from subcrop information of the depocenter in the West of the Kingdom and also from the outcrop area have to be modified.

These data have important implications on reservoir properties of the Wajid sandstone. The sandy deposits guarantee a high primary porosity and permeability up to 1 D. Bioturbation leads to pronounced anisotropy in some horizons. Of major importance, however, are late diagenetic cementation effects which focus on faults, fractures and horizontal to subhorizontal discontinuities. Most widespread is iron cementation which makes up almost impermeable seals and separates reservoirs horizontally and vertically. The primary control on reservoir quality is due to a gradual facies change from W to E. Fine-grained silty layers are increasingly intercalated towards the E but are almost completely absent in the W. Consequently, in the western area, the Wajid Group forms a combined reservoir but in the subsurface is separated into two layers.

Rapid urbanization in Lagos has increased the demand for water in recent years. With the aim of delineating the geometry and distribution of fresh water aquifers in the study area, Vertical Electrical Sounding (VES) were carried out at 25 locations; five each on a 100m long traverse and 1-D inversion of the VES data with pseudo 2-D presentation was carried out. The inverted resistivity models were calibrated with borehole data in the vicinity of the survey area. Maximum of four layers geo-electric layers were delineated: Hard peaty clay (15-52 ohm-m), sandy clay (58-119 ohm-m), fine sand (107-258 ohm-m) and medium sand/ coarse sand (260-568 ohm-m). The variety of sands in the area constitutes the aquifers in the study area. Depths to the tops of these aquifers range from 0-100m in both confined and unconfined conditions. This study recommends only the confined aquifers for development as the unconfined ones are prone to contaminations.

Drainage and lineament characteristics of a watershed provide important clues about the hydrogeology of the area. Information about the above characteristics derived from satellite imageries (IRS-IB) aided by field verifications and subsequently analyzed in Geographical Information System (GIS) environment can provide a composite map and which can be used for adopting a suitable strategy for managing watersheds in a better way particularly in relation to the augmentation of the status of groundwater by artificial recharge methods.

On the basis of the above concept, drainage, lineament and hydro geomorphic study of the upper catchment area of Kumari basin, Purulia, eastern India have been performed for demarcating prospective sites for construction of artificial recharge structures. Granitic lithology and uneven topography indicate that the surface run-off is high and infiltration is low and therefore groundwater recharge is inadequate in the area. So, mainly to keep the irrigation practice and drinking water supply alive, groundwater condition has to be improved by artificial recharge method. Integrating different types of thematic layers like drainage density, lineament density, hydro geomorphology in a GIS environment; it has been possible to generate a composite map showing prospective sites for construction of artificial recharge structures.

The main parameter that controls the groundwater flow regime in fractured aquifers is the fracture pattern. Its description is crucial for a hydrogeologic/hydraulic or geotechnical study. This paper, aims to describe and analyze the basic characteristics of the fracture pattern in Naxos Island, Greece. The parameters that were analyzed are: a) the frequency and spatial location of the fractures, b) the orientation of fractures, c) the dimensions of fractures, d) the density of fractures and e) the degree of fracture intersection. These parameters were analyzed separately for every dominant lithology of the study area.

The analysis revealed that there are five classes of fracture orientation in the study area, indicating a straight link between faults and fractures. The fragmentation in all lithologies is characterized by high degree of uniformity and very high density and interconnection density of the fractures are observed in areas where the alternations between marbles, schists and amphibolites are very intense.

Lack of available water resources is a typical problem for the water supply of Greek islands which is difficult to be confronted with the use of groundwater resources (groundwater wells and springs). However, it is proved that the availability of water resources in Thassos island (N. Greece) is rather satisfactory due to the geological settings of the island itself. Although no water supply problems are observed during the winter months for the local population, the problem becomes quite distinct during the summer period due to the sudden increase in population attributed to the touristic development of the island. The interpretation of the water supply balance (water consumption vs. available water resources) leads to the conclusion that this balance is positive during winter in all municipal districts and negative during summer in 60% of the municipal districts.

This study seeks to determine the hydrological and hydrogeological properties of the basin of Yesilcay (Agva) Stream which runs 19.2 km through the settlement of Agva and flows into the Black Sea (Turkey). To this end, the precipitation and evaporation characteristics of the study area were calculated by means of the Thornthwaite (1948) and Schendel (1968) methods on the basis of the meteorological data for the last 45 years (1966-2010). It was deduced that the Schendel method yielded results very close to values of pan evaporation measured in the area. Therefore, this method is more suitable to use for the study area. The calculations performed reveal that precipitation occurring in the study area will not be sufficient to have access to the amount of water that can be used safely. Therefore, it is of great significance to utilize as water source the karstic limestones present in the study area, and Yesilcay and Goksu Streams flowing into the Black Sea.

Efficient Water Management is an important factor for regional development and requires a set of actions in order to manage water resources in a sustainable way. This paper describes a methodology of water resources exploitation, with the potential of creating small mountainous and upland reservoirs. This can be done with the integration of Geographic Information Systems (GIS), while using the SWAT hydrological modeling and Reservoir Simulation software. Andros Island was chosen as the study area. This project involves the hydrologic analysis and the assessment of runoff (using SWAT model for a 100 years simulation in the Afrouses basin). In two different selected sites, the feasibility of constructing a dam with the simultaneous creation of a reservoir based on annual failure rates of deliverability of certain volume of water is investigated.

The present paper is dealing with the analysis and characteristics of the discontinuous media, represented by the ophiolite nappe in central Euboea (Mantoudi). It is aiming at the conception, the development and the subsequent validation of an integrated methodology for the description of fissured rocks, in the frame of intrinsic vulnerability assessment and mapping. The vulnerability is not being considered as a characteristic of a particular element at risk, but as a peculiarity of a complex territorial system, in which the different elements are reciprocally linked in a functional way. In order to estimate and to define both the quality and quantity, a group of parameters are being considered. The estimation and definition of those parameters are based on the geoenvironmental conditions of an area that may be vulnerable to contamination, in order to distinguish the geological, geomorphologic and hydrogeological criteria that affect the environmental impact of hard rock aquifers. These criteria are being calibrated in GIS so as to be able to support a correct territorial planning and a suitable management of the water resources protecting its quality which is essential to increase efficient use of existing water supplies. Furthermore, a sensitivity analysis has been performed to evaluate the influence of single parameters on aquifer vulnerability assessment.

Groundwater recharge in karstic aquifers has to be determined taking into consideration the hydrogeological particularities of these aquifers. The APLIS method has been used to estimate the mean annual recharge in carbonate aquifers in southern Spain, expressed as a percentage of precipitation based on the variables altitude, slope, lithology, infiltration landform and soil type. The method developed for Mediterranean conditions, has been applied to a karstified evaporate aquifer in West Greece. In this paper, maps of the above variables have been drawn for the study area using a geographic information system. The autogenic groundwater recharge and the spatial distribution of the mean annual values by means of the APLIS method have been obtained. Because of the absence of previous studies about groundwater recharge estimations in the study area and detailed discharge values, it was impossible to corroborate the validity of the method in this phase of the research. In the frame of a research project taken place in the study area, discharge values are measured at the springs draining the system; thus the validation of the method will be done in the next step of this study.

The scope of this paper is to define the appropriate geoenvironmental parameters that directly affect the identification of the most suitable sites for sanitary landfill construction subject to hydrogeological data. The methodology developed in this research, includes four distinct stages of research, data collection, analysis, definition of the geological parameters, calibration and standardization of the criteria in a GIS environment and evaluation of suitability index corresponding to the most suitable sites for landfill construction. The preparation of the final map was the result of the combination between the thematic maps with respect to Analytical Hierarchy Process (AHP). The resulting land suitability is reported on a grading scale of low to high, which is, respectively, from least to most suitable areas.

The Amvrakia spring is located at the bottom of Meteora pillars and more specifically near the village of Kastraki (Kalambaka municipality). It is a seasonal spring since it functions only during the wet period. The Meteora conglomerates which dominate the area are characterized by large discontinuities creating a network of groundwater pathways above the impermeable strata of the underlying marls. The research targets was to define these water pathways in order to understand the mechanism of Amvrakia spring, by mapping the exposed discontinuity network and define their underground extension with the contribution of geophysical techniques. Electrical Resistivity Tomography (ERT) and Very Low Frequency (VLF) methodologies were applied. The VLF method is indicated for the detection of water-bearing fracture zones, but before the application of their filters they had to be processed for topographic corrections, as the area had not smooth relief. Five (5) VLF profiles were conducted with different directions around the spring’s area, in order to detect possible conductive zones in the conglomerates surrounding the study area. Moreover, two (2) ERT sections of a total length of 140m were carried out, parallel to existent VLF sections, for cross-checking the geophysical information. Both techniques revealed important conductive zones (<200 Ohm.m) from the south-eastern Meteora conglomerate pillars, possibly interpreted as discontinuities filled with water feeding the spring.

The geological and hydrogeological regime of Kea Island is presented, focusing on the fracture pattern analysis of the crystalline-schist mass outcrops the island. The combined use of field mapping and geological data digital analysis extracting lineament density maps and fracture intersection density maps reveals a high relationship between the fracture pattern and the groundwater occurrence. In order to obtain a complete description of the fracture network, the study area is mapped at various scales with the aid of GIS and remote sensing techniques were integrated along with the data gathered from field work. Remarkable correlations between the hydrochemical data of the main springs (located along the SE and NW part of the island), and the results of lineament analysis and the hydrolithological regime of Kea Island, contribute to extract an integrated conception for the relation of the groundwater potential with the structure of fissured rocks.

The groundwater chemistry and stable isotopic composition of aqueous C- and S-bearing species were determined for mineral waters from Monte Real and Curia Spas. The results support dedolomitization -dolomite dissolution occurs as the gypsum dissolves and calcite precipitates- as a principal geochemical process controlling Ca - SO

4

facies of these waters. Soil CO

2

of atmospheric origin and carbonate weathering are the primary sources of dissolved inorganic carbon (DIC). However, dissolution / precipitation of carbonates, through incongruent dissolution of dolomite, is the controlling factor for the evolution of the C isotopic composition of DIC, as shown by δ

13

C values of -11.8‰ (Monte Real) and -9.4‰ (Curia). When present, the dissolved sulphide species (δ

34

S

H2S

= -36.1‰ for Monte Real) appears to be derived from biogenic reduction of dissolved sulphate (δ

34

S

SO4

= +16.1‰ for Monte Real and +14.8‰ at Curia), itself derived from dissolution of Hettangian evaporites gypsum (δ

34

S

Gy

= +14.4‰).

Gas and water samples were collected at CO

2

-rich wells in the plain of Florina (N. Greece). Chemical and isotopic composition of the analysed gases reveals their main crustal origin even if a small but significant contribution of mantle derived gases can be recognized. As a consequence of CO

2

dissolution, HCO

3

-

is always the main dissolved anion while cationic composition allows us to distinguish at least two main groups characterized by Na or Ca as dominant dissolved cations. The water-rock interaction is strongly enhanced by the dissolution of CO

2

and the consequent lowering of pH. Such a process increases the mobility of some trace elements whose concentrations very often exceed UE drinking water limits. This study confirms that the Florina basin represents a good natural analogue of carbon storage systems and underscores the fact that possible deterioration of water quality due to CO

2

leaks of the reservoirs must be carefully taken in account.

The data on experimental works on the analysis of the chemical composition and the organic matter of the pore water extracted from bottom sediments of water bodies and shale rocks of aquifers are given here. It is shown that pore water can be a source of the secondary pollution of water bodies and underground water under the influence of natural and anthropogenic loads.

Nitrates is one of the most common groundwater pollutants. Being able to identify the source(s) as well as evaluating the denitrification capacity of aquifers can help shape appropriate remedial action. This paper aims to investigate the isotopic composition of nitrates in groundwater samples in order to identify primary and secondary nitrate sources as well as to evaluate denitrification potential of aquifers in Cyprus. A total of 135 groundwater samples from 12 different Ground Water Bodies (GWB) were analyzed for

15

N/

14

N and

18

O/

16

O. It was concluded that the dominant primary source of nitrate in rural Cyprus is fertilizers. For many samples a secondary nitrate source with an isotopic signature of organic source is contributing. This organic source is, in most cases, assumed to be manure. In 16% of the groundwater samples, manure was identified as the primary nitrate source. Finally, the potential of denitrification is seen in 21% of the samples from 7 different GWBs.

Water and rock samples were collected from the karstic aquifer hosted in the Mirambello region, NW of Lasithi. In both rock and groundwater samples REE were determined. The rare earth elements’ concentrations increase according to the groundwater flow. The origin of REE in groundwater along the recharge area of the aquifer is due to the dissolution of the mineral matter of the aquifer skeleton. Afterwards, they move conservatively showing a similar character with that of the REE of the hosting rocks. The REE concentrations in the water during their transportation within the aquifer are straightly connected to the physico-chemical conditions that prevail. The variations of REEs that have been observed in the brackish and in the freshwater coastal zone of the aquifer show that their behavior alters and they adopt similar character to those of the salt water rare earths. These variations show that the brackish zone and the penetration depth of sea water can be divided into a coastal karstic aquifer among the standardized diagrams of brackish and freshwater samples of the aquifer.

Groundwater samples collected twice, during March-April 2009 (wet period) and in November 2009 (dry period), from two aquifer systems, the karstic and granule type, covering the wider area of Koropi, and springs were analyzed for the elements Αs, Cd, Cr, Li, Se, B, Fe, Tl, U, Zn, Κ, Νa, Ca, Mg, Si, S by ICP-MS. The analytical data presented showed a small temporal variability and a significant variation in the Na, Ca, B, As, Li and Se concentrations in both aquifers. The range of B (1-4300 μg/L), As (0.5 - 68 μg/L, Se (0.13 - 230 μg/L) concentrations exceed often the recommended limits for drinking water (10 μg/L). A salient feature is that the Na-enrichment is accompanied by As, Se, Li and Cl and the very good positive correlation between the former and the latter elements. The recorded salinization (sea-water contribution to the aquifers) is attributed to their over exploitation. In general, the evaluation of the chemical characteristics of both aquifers and the lack of any correlation with Cr and Mg point to water contamination by anthropogenic activities rather than of natural sources. Therefore, industries should follow regulate for the restriction of heavy metal releases into the environment, and citizens should be informed about the potential risk for diseases connected with the use of water from drilling wells and the Loumparda springs.

Chemical characteristics of stream water at Asprolakkas hydrological basin were determined in February 2009 in order to examine the main factors controlling the hydrogeochemistry of the drainage system. A total of 20 surface water samples were collected and analyzed for the major ions K, Na, Ca, Mg, HCO

3

, SO

4

and the trace elements Fe, Pb, Zn, Mn, Cu, Ni, As, Sb, Mo and Ba. The application of R-mode factor analysis revealed that the polymetallic carbonate replacement type sulfide deposits, together with the porphyritic intrusions and the associated porphyry copper style mineralization, occurring in the studied area, impose fundamental control on the water chemistry. A third influencing factor includes the parameters As and HCO

3

and is attributed to the competitive behavior of As and bicarbonate ions, for filling in available absorption space on Fe(III) oxides. SEM-EDS methods, performed on retained filters from the filtration of representative water samples, showed that Pb is mainly transported by fine particulate matter. The chemical elements Mn, Zn, Mo and Sb are predominantly present as dissolved free ions, and correlate strongly with the electrical conductivity of the water samples.

The present study examines the hydrochemical characteristics that rise from trace and ultra-trace elements of Lesvos thermal springs. Six main thermal springs were sampled and analyzed extensively for a large set of parameters. The detected concentrations of REE (La, Ce, Nd, Gd, Er, and U) are attributed to specific geochemical processes and environmental conditions, such as complexation, acidic environment and elevated temperatures. The presence of As is related with epithermal sulphide gold mineralization, as well as the presence of Pb, Sb, Cu, Zn and Fe. Germanium is correlated with the existence of Si-rich acid volcanic formations and possibly with Cu-rich sulphide minerals. Thallium is enriched in thermal waters of Lesvos, compared with other geothermal fields, and consists a significant environmental threat for human environment, due to its presence at the majority of the sampled springs which are used for blaneotherapy purposes.

The present study examines the isotopic composition of a karstic groundwater system in Boeotia (Greece) and the factors that control its variations. For this purpose 42 samples were analyzed for oxygen and hydrogen stable isotopes, and their ratios defined the local groundwater isotope line (LGIL). The results showed a shift of the LGIL in comparison to LMWL, which is expressed by an enrichment of heavier isotopes and lower d-excess values. Apart from the ambient conditions that affect the initial isotopic signature, the secondary processes seem to be a major factor too. These processes are related to the specific geological and hydrogeological setting of the area and include the evaporation of soil water, mixing with paleowaters, hydraulic connection with groundwater systems of different isotope characteristics, and finally water-rock reactions with the karstic aquifer.

This article investigates the origin and chemical composition of the aquifer hosted in the coastal part near Pyrgos town as well as any possible connection with the tectonic structures of the area. The bedrock in the study area consists of Paleocene limestones of the Ionian zone and evaporites. The post-alpidic sediments consist mainly of clay, marl, siltstone and sandstone. Three major fault trends develop a complex fault system in the wider Pyrgos area. The tectonics and seismicity of the study area are active to date and have played a prominent role in the structure of post-alpidic sediments, the shaping of today’s relief, the development of the drainage network and the local hydrogeological characteristics. Groundwater samples can be classified into two groups based on their water type. The first group corresponds to fresh groundwater of Ca-Mg-HCO

3

-(SO

4

) type and the second to alkaline waters of Na-(Ca, Mg)-HCO

3

-SO

4

type. A number of samples classified into the second group are considered to be modified by rock-water interaction processes. Trace elements exhibit generally low concentrations, while boron concentrations suggest discrimination between the above two water groups. The correlations between different elements and their distribution maps suggest that the main fault of Vounargo provides a preferential path for deep circulation, transmission and mixing of deep and shallow groundwater.

Phenanthrene is used as a model hydrophobic organic compound to study the sorption properties of the Gulf of Aliveri (Greece) marine sediments. Sorption of hydrophobic organic compounds is mainly related to the organic matter present in the sediments. The presence of particles due to anthropogenic activity in the sediments can highly influence their sorption behavior. Sediments from the Gulf of Aliveri contain different proportions of such particles i.e., lignite, coal, and char. The hypothesis of the present study is that salinity can affect the fate of this pollutant by affecting the degree of sorption nonlinearity and sorption capacity. Since the sorption nonlinearity is a function of heterogeneity, different materials are used to compare their sorption behavior in solutions with and without salinity. Results expected from this study include a) the surface properties of the different sediments and the materials tested and b) sorption capacities in i) fresh and ii) salt water for phenanthrene. In general, it is observed that for carbonaceous particles and sediments containing such particles at lower phenanthrene concentrations, sorption in saltwater solutions is lower than in fresh water solutions.

Loussi Polje, situated in the west of Helmos Mountain, N Peloponnesus, Greece, drains carbonate aquifers through several small karst springs. In the area, which is scarcely populated, few boreholes can be found, mostly used for irrigation purposes. In the framework of an integrated study of karst aquifer vulnerability, the physical and chemical characteristics of the water from these springs and boreholes were studied for two years. This paper deals with the hydrochemical analysis and results, in order to better understand the main factors that control the groundwater composition and its seasonal variations and to reveal the existence of any possible source of contamination.

Concentrations of inorganic nutrients (nitrate, nitrite, phosphate, silicate and ammonium), trace metals (Cd, Cu, Ni, Fe, Pb), Total Organic Carbon (TOC), Dissolved Oxygen (DO) and organic pollutants (pesticides and insecticides, organochlorines, hydrocarbons, etc) were determined in samples taken from Kalogria Bay submarine spring and the adjacent marine environment (SW Aegean Sea), in order to present, for the first time, the chemical characteristics of Submarine Groundwater Discharge (SGD) in Kalogria Bay and to study the effect of the SGD on the marine ecosystem. We also used estimations of the mean monthly spring discharge, in order to quantify the release of chemical constituents via the submarine discharge system to the marine environment. The results show that the loads of chemical constituents released by the SGD in the marine environment of Kalogria Bay do not impact the functioning of the marine ecosystem. All the chemical constituents measured, were well below the criteria set by the Directive 98/83/EC of 3

rd

of November 1998 on the quality of water intended for human consumption.

The south Aegean volcanic arc and Ikaria island are characterised by the presence of many thermal springs. Hydrochemical data from 46 springs were used to get insight on their water quality. Highest temperatures were recorded in Ikaria (58.3 °C), Santorini (50 °C) and Milos (43.7 °C). There is a wide range of major ions’ concentration but the predominant water type is Na-Cl. The composition of waters is mainly influenced by seawater intrusion and secondly by mixing with deep hydrothermal and shallow meteoric waters. The trace elements’ concentration is mainly controlled by high temperature dissolution of primary volcanic minerals and precipitation of secondary solid phases. Factor analysis explains 90% of the total compositional variance with a five factor model.

The application of an in-situ gamma-ray spectrometer for long-term measurements of natural radionuclides into groundwater emanating from submarine groundwater discharge (SGD) sources is described. The system (named KATERINA) has been developed for aquatic applications by Hellenic Centre for Marine Research and as a preliminary study it was deployed at three pilot SGD sites in Greece. After the initial deployment into the lake Tsivlou where background spectrum was obtained, the system was deployed for several hours in Hellenic coastal submarine groundwater sources at Chalkida, Stoupa and Korfos. The radon progenies activity concentration at Chalkida measured in a range from 1.2 to 1.3 Bq/L while at Stoupa from 2.4 to 2.6 Bq/L. Also, the concentration of the radon progenies in the region of Korfos varied from 1.4 to 2.3 Bq/L and an inversely linear dependency with salinity values was observed. The system monitoring radon progeny variations may contribute to hydrological studies concerning the transport, the emanation and the quantification of the groundwater using radiotracing techniques.

The conceptual model and the hydrochemical characteristics of the aquifer system of Vistonis plain in Northeastern Greece are presented. The study area is a rural region whose irrigation needs are met by the semi-confined aquifer system. Studies were undertaken in years 2003-2005 which utilized geological data, pumping test data and groundwater level measurements, in order to investigate the hydrogeological conditions of the semi-confined aquifer system of the study area. Based on this data a FLOWPATH II simulation was developed. The hydrochemical characteristics of the aquifer system of the study area were analyzed using basic statistics, Principal Component Analysis (PCA) and the expanded Durov diagram. The hydrogeological characteristics of the aquifer system vary significantly across the study area and are largely the result of contrasts in depositional environments. FLOWPATH II showed a clear tendency for groundwater to flow from a NW to a SE or E direction. The groundwater chemical analyses results showed that, the aquifer is locally affected by a geothermal field. PCA rendered seven significant PCs (eigenvalue > 1), explaining 76.8% of the total variance of the dataset. PCA revealed factors influenced by anthropogenic activities, such as fertilizer application and waste disposal, and also naturally induced hydrochemical processes.

The Kotyli springs are located in northern Greece on the NW part of Rhodope Mountains, which is the oldest mountain range of the country. The climate is semi-humid with water excess and deficiency during winter and summer, respectively. The area belongs to the Rhodope isopic zone, specifically in Sidironero unit, consisting of a Paleozoic sequence of neritic-sea metamorphosed sediments and plutonic intrusions successed by tertiary plutonic, volcanic and coastal deposits. The fractured granodiorites in valley depression areas gives rise to most of the springs, the discharge values and the overall hydrogeological data being consistent with this scenario. Hydrogeochemical analyses performed on samples showed that the springs are classified to the Na-Ca-Cl-HCO

3

type, except for two of the springs in Pacni area classified to the Na-K-Ca-Cl-HCO

3

type and the Aimonio spring which is classified to the Ca-Cl-HCO

3

type. The low values of the dissolved minerals, expressed in TDS and electric conductivity values indicate a function mechanism, which involves the existence of a shallow aquifer in fractured rock with restricted size and the development of the springs at their current site due to the presence of depressions in the small valleys of the area. However, the function mechanism of the Aimonio spring involves the existence of a shallow aquifer in slightly carstified marbles and the development of the spring at its current site due to the presence of a depression in the small valley of the area.

Subsurface contamination with oil poses a threat to groundwater quality on the whole territory of Ukraine. The methods of search and prospecting of contaminated plums were analyzed. Oil behaviour in the subsurface and the methods of remediation were studied. The effectiveness of aviation kerosene removal was examined in a sandy column. Nonhazardous distances from a contamination source to water-supply wells for different hydrogeological conditions were determined by mathematical modelling. The case of drinking groundwater contamination with oil in Kherson City is examined.

A set of indices (LOS), based on a deterministic approach and regression analysis were used to assess intrinsic and specific vulnerability to nitrates in Ferrara Province, in northern Italy. To calibrate the LOS indices, using multiple regression analysis, the simulation results of GLEAMS model for combinations of different soil properties, topography and climatic conditions of a reference fieldcrop were used as “observed values”. Results of model were introduced in a GIS environment to obtain the vulnerability maps. Maps of water and nitrogen losses under the root zone (LOSW-P and LOSN-PN respectively) were used to obtain the map of relative concentration of percolated water (RCPW). Data on individual crops were used to calculate specific crop evapotranspiration rates (ETc) from potential evapotranspiration (PE). ETc values replaced PE values in the indices, to obtain both specific vulnerability map for water and nitrogen losses under the root zone (LOSW-P mod; LOSN-PN mod) and for relative nitrogen concentration of percolated water (RCPW mod). The RCPW mod map shows that concentration of nitrogen losses under the root zone is under water drinking limit of 50 mg/L (WFD; 2006/118/EC) all over the territory with highest concentrations along small areas of the coastal zone, where sandy textured soil are present (coastal dunes) and lowest concentrations where ETc is higher.

The study was conducted in Ferrara Province (Italy), a lowland area covering 2636 km

2

, located in the southern part of the Po River Delta. It is an intensively cultivated area, with more than 50% of land cultivated with winter cereals (32.11%) and maize (22.63%). The main nitrogen fertilizer used in this area is synthetic urea which is suspected to cause nitrate leaching towards shallow groundwater. A network of 56 piezometers, homogeneously distributed throughout the whole area, was installed in order to monitor both water table fluctuations and nitrogen species distributions in the shallow aquifer, over time. Data collected at the end of November 2010 were used to obtain maps of water table, urea (CO(NH

2

)

2

), ammonium (NH

4

+

), nitrate (NO

3

-

) and nitrite (NO

2

-

) distributions. Maps show an accumulation of NH

4

+

overlapping a stagnant zone, where drained peaty soils are present. The peaty soils are characterized by a pH ranging between moderately acid and slightly acid, and by high values of organic matter content. Along the drainage line induced by peaty soils dewatering, the flow velocity is very low or almost motionless, determining anaerobic conditions. Instead, the largest accumulation NO

3

-

is observed in the Eastern part of the province, where the groundwater head gradient is higher and soils are characterized by values of pH that range between 8.1 and 8.3, providing the best conditions for nitrification processes.

During the period 2004-2008 a hydrogeological investigation project was conducted by an IGME/Hydrogeology Department team in the area of North Peloponnesus, funded by the 3rd EU Framework Directive budget. In 2008 using the results of this investigation and implementing article 5 of Water Framework Directive 60/2000/EU as well as articles of Ground Water Directive 2006/118/EU, eleven ground water bodies (management units) were able to be identified in this area. Using the DPSIR criteria six of them found to be needed further characterization and two out of these six were concluded not to be able to fulfil the required good (quantitative and chemical) groundwater status by 2015. All these results are presented here.

Groundwater samples were collected from 43 wells of the alluvial deposits aquifer of Sperchios’ river basin in 2007. The groundwater quality of the aquifer is influenced by various natural and anthropogenic factors. Evaluation of water quality for drinking and irrigation purposes is discussed. A comparison of these samples with the corresponding samples collected from IGME in 1971, for the same or nearby wells, was made. The spatial distribution of ions concentration was made using the inverse distance weighting (IDW) interpolation method of a Geographical Information System (GIS). The results showed an increase in most of the main chemical elements, such as Cl

-

, ΝΟ

3

+

and SO

4

2-

. Finally, increased concentrations of several heavy minerals were recorded having values that overcome the maximum allowable limits set by the EU.

The aim of the present essay is to evaluate the groundwater quality in the coastal alluvial aquifer of the Atalanti basin (Fthiotida, Greece). For this reason, data from the physical and chemical analyses of groundwater samples for eight sampling periods were collected and nitrate pollution was studied thoroughly. The period of June 2005 is the most appropriate and representative as far as dispersion and number of samples are concerned. The most dominant water type is Mg-(Ca)-HCO

3

, due to the presence of dolomite and ultrabasic rocks. Moreover, the Na-Cl hydrochemical type is recorded near the coast line, due to seawater intrusion. Furthermore, it can be concluded that a) the high nitrates concentration values are related with the intensified agricultural production, the applied fertilizers and the absence of sewage systems, b) higher Mg concentration and Mg/Ca ratio values are observed near the coastline due to high Mg concentration in sediments and seawater intrusion, c) high Cl and Ca concentration in the southern area are connected with the discharge of the karst, saline spring in Tragana and seawater intrusion, d) according to factor analysis there are three main factors that are related with the aquifer salinization, the dolomite/ultrabasic rocks dissolution and the nitrate pollution with intense use of fertilizers, e) according to the cluster analysis, there are two clusters of water samples in Atalanti: the ones near the coastline with increased hardness, that are affected by salts and the ones in the central basin with reduced hardness, due to the short residence time in the ground Finally, some recommendations are proposed in order to protect and improve the groundwater quality in the study area.

This paper summarises the hydrochemical characteristics of the main aquifers of the island of Zakynthos, in the Ionian Sea. A total of 677 groundwater samples were collected from 139 points between 2004 and 2008. The karstic limestone of the mount Vrachionas in the west comprises the major drinking water supply of the island. Increased water demand resulted in the overexploitation and the encroachment of saline water intrusion to the north and south of Vrachionas. Chloride concentrations exceed drinking water threshold in 40% of the samples. Simple groundwater-seawater mixing is the main process occurring within the limestone aquifer. In the east, the confined multilayered Neogene aquifer comprises the secondary drinking water supply of the island. Saline intrusion in this area is limited due to geological constraints and the water is of good quality. Groundwater is clustered in 4 different groups depending on the prevailing hydrochemical process. The alluvial deposits in the central part of the island comprise a shallow localised aquifer pumped mainly for irrigation. This minor aquifer provides good quality irrigation water with some exceedances in chloride and sulphide. Groundwater in this aquifer is a result of simple mixing between fresh and sea water. Trace elements were also analysed resulting in values within the drinking limits.

Loussi polje, located in North Peloponnesus on the SE of Kalavryta village is a very interesting but little studied karst area. Water from karst springs and boreholes that drain the local carbonate aquifers is exclusively used for water supply and irrigation purposes in this scarcely populated area. An attempt to delineate protection zones in karstic aquifers was made, by assessing the groundwater vulnerability to pollution. PRESK, an adaptation of the RISKE groundwater vulnerability method of carbonate aquifers was applied. Modifications were necessary in order to meet with the specificity of Loussi karst terrain. PRESK method takes into account the protective role of topography in combination with vegetation (P factor), the nature of geological formations (R), the presence of epikarst (E), the existence of an overlying soil cover above carbonate aquifers (S) and the degree of karstification of the carbonate formations themselves. Groundwater vulnerability was assessed for both Olonos - Pindos and Tripolis carbonate aquifers of the study area.

The assessment of an aquifers’ vulnerability to pollution is of great importance, and can be used as a tool to augment planning, effective protection and management of groundwater resources’ quality, especially in the case of karstic aquifers. The present study aims to assess the intrinsic vulnerability of a karstic groundwater system, with the use of a modified version of the PI method. The assessments are functional to the effectiveness of the protective cover, as well as to the degree to which the protective cover is bypassed due to flow conditions. The used data was obtained by field work, empirical and semi-quantitative approaches regarding lithology, fissuring and karstification of bedrock, soil characteristics, hydrology, hydrogeology, topography and vegetation. The combinational effect of the above parameters, as processed with the aid of a GIS system, yielded the final calculation of the protection factor (π) and subsequently the vulnerability of the aquifer to pollution.

Proper management of coastal aquifers often demands the assessment of groundwater vulnerability achieved by the application of different vulnerability indexes, each one being developed for specific type of contamination. This paper presents the application of widely used vulnerability indexes such as DRASTIC, with respect to nitrate contamination, and GALDIT, regarding aquifers vulnerability to seawater intrusion, in order to assess the vulnerability of the coastal aquifer of the agricultural area of Xilagani, N. Greece. The results have been linked with GIS for the visualization of vulnerability, while they are also compared and hence evaluated and verified with field data of nitrates and Revelle values distribution.

Three different methods of intrinsic groundwater vulnerability mapping were applied in the alluvial aquifer of Florina basin (NW Greece), covering an area of 180 km

2

. Vulnerability maps were produced using the parametric methods DRASTIC, GOD, AVI and the results are compared and evaluated. The three methods use different number of parameters with different weight and produce relatively different results. The comparison between these methods shows that the GOD method has the stronger correlation with the other two methods and produces vulnerability maps comparable with DRASTIC and AVI method.

The study of the hydrogeological conditions of the Stoupa-Ag. Nikolaos region (W. Mani) aimed the investigation of groundwater quality, analyzing the factors that caused its degradation due to seawater intrusion and anthropogenic effects. The study area is consisted of kastified carbonate rocks, flysch, Neogene sediments and Quaternary deposits. Two major aquifers are been distinguished, the karstic aquifer which is developed within the karstic carbonate formations and the shallow aquifer established within the Quaternary deposits and Neogene sediments of the plain area. Groundwater discharges through coastal and submarine springs into the Messinian gulf. The most dominant watertypes of the springs in mountainous and semi mountainous areas are Ca-HCO

3

and Ca-Mg-HCO

3

, while no influence of surface pollutants is detected. On the other hand, in the plain area, the phreatic aquifer is characterized by Ca-Mg-Na-Cl-HCO

3

and Mg-Na-Cl-SO

4

-HCO

3

watertypes, being influenced by the seawater intrusion - due to the overexploitation of the aquifer and the intense anthropogenic interference - is considered to be inappropriate for human consumption.

In this paper, groundwater quality characteristics of the coastal area of Almyros hydrological basin, which belongs in the Magnesia Prefecture, Greece are analyzed. Geological, tectonic and stromatographic conditions of the coastal area, are described. Description and analysis of the hydrogeological conditions that dominate the region and the quality characteristics of groundwater resources of the area follows. Particular attention is given to the phenomena of seawater intrusion and nitrate pollution. The general conclusion is that groundwater resources of the study area are affected by the seawater intrusion phenomenon, mainly at the northern and the southern area of the coastal region, due to local geological and tectonic characteristics, refreshing conditions and overexploitation of the groundwater resources.

The studied area of Anthele, is located in the last part (delta) of Sperchios River (Fthiotida prefecture). Τhe most significant problem that confronts, is the deterioration of surface water quality. Αt the eastern part of Sperchios River up to the coastline the water quality appears to be improper for irrigation. The water coming from the irrigation – drainage canals of the agricultural redistribution, in the east, south-southeastern part of the area is saline. Groundwater quality, in the west, between Anthele village and the national road appears to be good. At the eastern part of Anthele there are indications of degradation. The main sources of pollution are the agricultural activities, the deposition of solid and liquid wastes inside Sperchios River, the mineral - thermal waters in the south and southeast part and the intrusion of the sea in the low parts of Sperchios River and the coastal lowland zone. The region is declared as protected area (Natura), because of the appearance of specific environmental and ecological characteristics. The preservation and exploitation of the water resources is an important necessity for the improvement and further development of the area.

Groundwater samples were collected from 58 sampling sites of the Megara basin aiming to describe the groundwater quality in relation to geology and anthropogenic activities. The methodology applied in this study includes chemical analysis, statistical analysis, GIS database and comparison of the groundwater contents with quality standards given by the Dir.98/83/EC. The elevated Cr

total

(up to 70.3 μg/L), Ni (up to 25.39 μg/L) and Mn (up to 87.77 μg/L) groundwater concentrations of Megara basin constitute a natural case of contamination; while the high NO

3

-

(up to 411 mg/L) and PO

4

3-

(up to 4.74 mg/L) groundwater concentrations could be attributed to the application of fertilizers and leakage of domestic sewage. The elevated Cl

-

(up to 3954.7 mg/L) and TDS (up to 8027 mg/L) groundwater contents recorded in coastal areas are attributed to the mixing of groundwater with seawater.

Ground water samples collected from 21 wells located in the hydrogeological, coal-bearing basin of Sarigiol, Western Macedonia, Greece have been analysed for determining trace elements concentrations. The water quality assessment reveals that the concentrations of heavy and toxic metals and trace elements are, for most of the samples; bellow the allowable limits specified by the existing regulatory framework. The trace elements As, Cd, Cu, Zn, V, Co, Be, B and Al are detected in very low concentrations, while Τi and Sn are detected in very low to negligible concentrations. The elements Pb, Hg, Ni, Mo, Cr

tot

and Ba are present in low concentrations. This is also the case for Sr, Te and Bi. For these elements the legal framework does not specify allowable limits. Concentrations closed to or above the allowable limits have been determined for Sb and Tl. In addition, samples of water that have been collected from certain parts of Sarigiol basin show concentrations above the allowable limits for Al, Be, Ni, Cr, Sr and Se. However, the enrichment ratio, compared to the allowable limits determined by laws and regulations, is very low. Based on the results presented and evaluated in this contribution, it is concluded that adverse impacts to the human and natural environment are not probable. The water pumped from the wells of the area can be used safely for irrigation and water supply.

The Thriassio plain is located west of the city of Athens, in Attica prefecture, Greece, and is a favorable site for industrial development. The intense industrialization of the last few decades in the Thriassio plain has caused major pollution problems. Thus, several pollutants produced in this area are seriously polluting the air, soil and water. The present case study emphasizes on the hydrochemical conditions of Thriassio Plain’s aquifers, including the study of the geological and hydrogeological factors. In order to determine the factors influencing water quality in the study area, groundwater samples from springs, wells and boreholes were analyzed. The graphical representations of the chemical analyses show that the main parameter controlling the chemical composition of groundwater is the human factor (industrial development, agricultural activities, groundwater over-exploitation). This results in serious degradation of groundwater quality in the study area due to seawater intrusion and heavy metals pollution.

Groundwater protection from microbial contamination necessitates a solid understanding of the factors controlling the migration and retention of pathogenic organisms (biocolloids) in the subsurface. Although coliform bacteria and coliphages are used worldwide to indicate fecal pollution of groundwater, their transport behavior is not fully understood. This study focuses on the transport behavior of three waterborne pathogens (

Escherichia coli

, MS2, and ΦX174) in laboratory-scale columns packed with clean quartz sand. Three different grain sizes and three pore water velocities were examined. The attachment behavior of

Escherichia coli

, MS2, and ΦX174 onto quartz sand was evaluated. The mass recoveries of the biocolloids examined were shown to be proportional to the sand size, and they were shown to be highest for

Escherichia coli

and lowest for MS2. The single collector removal and collision efficiencies were quantified using the classical colloid filtration theory.

The Patraikos Gulf is situated in Western Greece between the mainland and the Peloponnese peninsula, opening into the Ionian Sea on the west. The Evinos, Glafkos and Pirros Rivers flow into the Gulf and the city of Patras, with its busy port, lies on the east side of the gulf. Glafkos is the largest river in Patras area and is considered to be a factor of pollution of the gulf, as it carries large amounts of water and sludge. Determination of metal concentrations (Fe, Mg, Ca, Ni, Zn) was attempted in sea water of Glafkos estuary on December 2009, February and March 2010. In addition, activity concentration values of the natural radionuclides

238

U,

232

Th,

226

Ra,

40

K and of the artificial

137

Cs were measured in sediments of the river and its estuary. In general, the results are close to the bibliographic ones, while in most of the cases there is statistically significant deviation between the metal concentrations in relation with the months.

The treatment of wastewater from Sindos industrial area of Thessaloniki, Greece (initial pH 7.8) with the Hellenic Natural Zeolite (HENAZE), resulted to clear water of pH 7.3, free of odours and improved by 93% in the colour, 69% in the chemical oxygen demand (COD), >97% in the P

2

O

5

removal, 54% in the NO

3

removal and 77% in the Cr removal. The sorption and fixation of the different species from the wastewater by the micro- meso- and macroporous of HENAZE can be attributed to absorption (mainly ion exchange), adsorption and surface precipitation processes. Important role in these processes play the surface Broensted acidic and Lewis basic sites of the HEU-type zeolite. In addition the HENAZE treatment gave odourless and cohesive zeosludge, suitable for safe deposition since the fixation of dangerous components into the micro- meso- and macroporous of HENAZE, prevents the seepage of them by the rain water, protecting thus the quality of surface and underground waters. The used HENAZE sample, comes from Ntrista stream area of Petrota village (Evros Prefecture, Northeastern Greece) and contains 88 wt.% HEU-type zeolite, 4 wt.% mica + clays (92 wt.% microporous minerals), 5 wt.% feldspars and 3 wt.% SiO

2

-phases (quartz + cristobalite). The mineralogical composition and the physico-chemical properties, make the HENAZE suitable material for numerous environmental, industrial, agricultural and aquacultural applications.

A large tank (4x8x1.4 m), equipped with 26 standard piezometers and six temperature loggers with four channels each installed at different depth, is used to carry out thermal monitoring test and investigate environmental impact of heat borehole exchange. Loamy sediments (35 m

3

), used to fill the tank, were excavated from an unconfined alluvial aquifer near Ferrara (Northern Italy). To evaluate spatial heterogeneity, the tank’s filling material was characterized via slug tests and grain size distribution analysis. Constant heat input rate test was conducted by originating a heat plume using a groundwater heat exchanger (GHE). Temperature was monitored in continuous via data loggers. The effect of heat borehole exchange was small compared with the temperature applied. Results show a heat flux dominated by temperature gradient and thermal conduction. The effect of hydraulic conductivity heterogeneity on heat plume development is discussed. Tank model presented in this research looks to be suitable for heat transport modeling. Recommendations for future development of the research and future groundwater and heat transport modeling are also reported.

Nisyros is characterised by a high enthalpy geothermal system. Numerous thermal springs are concentrated near the coastline with temperatures of 27°-43°C. Isotopic composition of Nisyros thermal water samples reveals mixing between

seawater

with

magmatic water

and

geothermal steam

and the possible involvement of

groundwater

and/or

meteoric water

. Combined silica and K

2

/Mg geothermometry indicates temperatures of 90°-140°C while deep geothermal fluids display temperatures of 245°C and steam heated samples approximately 210°C. We have calculated the initial temperature of the hot component of mixing using the diagram of dissolved SiO

2

versus enthalpy. We propose that the geothermal system of Nisyros consists of two major reservoirs. A deeper one (1400-1800 m) with temperatures greater than 245°C which is the result of mixing between

seawater

and

primary geothermal fluid

and hosts hot waters of high enthalpy which cool adiabatically and ascend, due to separation of vapours, to the shallow reservoir (0-500m) of lower enthalpy. In this mixing occurs mixing between

seawater

and

geothermal vapours

and/or

underground water

or

meteoric water

with a

hot water component

of approximately 180°-220°C. The latter is derived from the ascent of the high enthalpy waters into the shallow reservoir which represents the mixing zone of the geothermal system and is characterised by lower enthalpy compared to the deeper reservoir displaying temperatures of 90°-140°C whilst the temperature of the separated vapours are approximately 225°C.

The Altınoluk-Gure region is at the foot of Mount Kazdag. There are many thermal springs to the east of the area (Gure ande Kucukcetmi). Because of the geologic and tectonic settings, it is considered that the Altınoluk-Gure-Narlı area may have a geothermal potential as well. In this study the hydrochemical data were mapped out by sampling from the existing springs and, in order to determine the geothermal potentiality of the region, the relationship between volcanism, tectonics and springs were investigated.

The hydrogeological research conducted in the Limnos Island showed the existence of three confined volcanic aquifers overlying the impermeable flysch. The limited natural recharge induced by the low annual areal precipitation and the overexploitation of the aquifers for irrigation and drinking water supply lead to groundwater salinization due to seawater intrusion. The wider Romanou area has been affected in a higher grade because bears the greatest number of agricultural activities. The extensive application of nitrogenous fertilizers results in nitrates contamination deteriorating thus the groundwater quality. Ion exchange is the dominant hydrochemical process; however, the enrichment of groundwater in various metals, especially in potassium and magnesium, is attributed to rock and mineral weathering and dissolution.

The Riza - Antirrio area constitutes a new low enthalpy geothermal field located on the northern side of the Corinthian Gulf in Western Greece. After a detailed and systematic reconnaissance study including evaluation of geological and tectonic setting of the area, geophysical surveys, water temperature measurements at the heads of the existing irrigation and water supply wells, sampling and hydrochemical study, 4 geothermal wells were drilled. The first geothermal exploration borehole was drilled to a depth of 402 m during 1998-99. Two more wells were drilled in the period 2005-2006. Exploration borehole GL-1 was drilled down to 275.5 m and the temperature of 38°C was recorded at 270 m. Production well GLP-1 has a depth of 229 m and it yields 25 kg/s water of 36°C and Na-Cl type with TDS content of 45.7 g/L. The geothermal reservoir of this low enthalpy field composed of Eocene limestones is located at depths of about 110-250 m.

In Europe numerous urban areas are located in the flood plains of the rivers. Sedimentary media (alluvial sediments, deltas, etc.) form particular frequently occurring environments within these valley fills. However, sedimentary media are normally significant aquifers due to their high permeability, storage capacity, interaction with surface water, etc. A reliable management of the hydraulic resources in urban areas can be performed only by using modeling. The models can provide accurate results if they correctly reproduce the hydrogeological processes. Tools and methodologies should allow the representation in three dimensions of the geological record heterogeneity and of its spatial distribution as well as the interaction of the groundwater with the urban infrastructure. The paper will focus on the main aspects of these instruments, which are currently developed within a national research project, that have to support 3D hydrogeological modeling. Within this project a software platform has been developed containing methodologies and tools that facilitate the integration of the 3D geological models in sedimentary media into the hydrogeological modeling of flow and contaminant transport. This is composed by a geospatial database and a set of tools allowing accurate stratigraphical analysis. An application of this platform is currently developed for the Moesic aquifer system (Bucharest city Region).

Increase of water demand in Larissa Plain due to extensive cultivation, fulfilled by the over-exploitation of ground-water resource, lead to an intensive subsidence phenomenon causing in turns considerable damages to many buildings. DInSAR technique was proven to be a useful tool to measure ground deformation despite the unfavorable conditions inducing decorrelation. By exploiting differential interferometric pairs of short temporal separation and perpendicular baselines, it was possible to identify the area affected by ground deformation. Seasonal deformation signals were recognized at the southwestern part of the basin, reaching several centimeters during summer period.

This paper deals with the land subsidence due to groundwater overexploitation in Anargyri village (Florina prefecture, West Macedonia). The decline of groundwater table is necessary for lignite exploitation by the Public Power Corporation (PPC). The lignite deposits are occurred in Neogene sediments, consisting of alternations of clayey and marly layers. In these deposits are developed successive confined aquifers. The overexploitation of these aquifers had led in a decline of groundwater table, ranging between 30-40 m during the last years. Land subsidence phenomena resulted in ruptures on surface and buildings, rendering most of the houses uninhabitable. The ruptures on surface were examined in relation to geological and hydrogeological conditions and conclusions are drawn.