Christos Petalas

Soil salinization in the agricultural lands of Rhodope District, northeastern Greece

The objective of this study was to identify seasonal and spatial trends and soil salinization patterns in a part of Rhodope District irrigated land, northeastern Greece, located east of Vistonis Lagoon. The study area is irrigated from a coastal aquifer, where salt water intrusion occurs because of extensive groundwater withdrawals. Fourteen monitoring sites were established in harvest fields in the study area, where soil samples were collected. Electrical conductivity (ECe), pH, and ion concentrations were determined in the saturated paste extract of the soil samples in the laboratory using standard methods. A clear tendency was observed for ECe to increase from April to September, i.e., within the irrigation period, indicating the effect of saline groundwater to soil. In the last years, the change from moderately sensitive (e.g., corn) to moderately tolerant crops (e.g., cotton) in the south part of the study area indicates the impacts of soil salinity. The study proposes management methods to alleviate this problem.

A preliminary assessment of hydrogeological features and selected anthropogenic impacts on an alluvial fan aquifer system in Greece

An investigation was carried out to delineate the hydrogeologic framework and to understand groundwater quality of the Kompsatos River fan aquifer system, northeastern Greece, as well as to assess environmental impact induced by human activities. As groundwater is the only major source of water in this area, it is important to know the effect of geological formations, and anthropogenic activities on groundwater chemistry and environment. A thorough hydrogeological study was performed during the period 2004–2007. The differential river gauging method was used for estimating the volume of water leaking from (or discharging into) the river. Groundwater samples were collected from 89 monitoring wells, during the summer period of 2007, and analyzed for major ions and trace elements. A potential reservoir of groundwater is formed within the Kompsatos River fan. The aquifer system/Kompsatos River interaction is the outstanding feature of this area. Ca–Mg–HCO3–SO4 is the dominant water type as a result of dissolving carbonate salts. B, Ba, Mn, Li, Sr, and Zn are the most abundant trace elements in groundwater. Both the major-ion chemistry and trace element enrichment of the groundwater are controlled by mineral dissolution and water–rock interaction. Nitrate contamination of groundwater is related to agricultural practices. An improperly constructed drainage system led locally to salinization of groundwater. Channelization has caused considerable disruption to the river ecosystem. The eventual construction of a dam on the river will adversely affect the environment and the aquifer system. The lack of managerial policy for water is putting environmental resources and water supply in jeopardy.

Monitoring and modeling of two alluvial aquifers in lower Nestos river basin, Northern Greece

A groundwater monitoring and modeling program in two aquifers within the lower Nestos river basin in Northern Greece is presented. A monitoring network of 54 wells was developed in the two study areas, and groundwater level measurements and water quality sample analyses were conducted for a period of 2.5 years, from March 2007 to October 2009. The field data were used for the calibration and verification of the mathematical model MODFLOW in the two aquifers. The validated model was used to examine ten alternative management scenarios regarding groundwater abstraction in the two aquifers. The study showed that MODFLOW, if properly validated, is a useful and flexible tool in groundwater resources management.

Evaluation of multivariate statistical methods for the identification of groundwater facies, in a multilayered coastal aquifer

The multilayered coastal aquifer system of the southern Rhodope province in North Greece was selected to examine the applicability of multivariate statistical methods in the investigation of groundwater variability and to evaluate their performance in the presence of overlapping processes. The aquifer system which forms the main source of water supply to numerous productive wells in the area, drilled at various depth horizons, faces serious degradation of groundwater quality. A widespread sampling survey was conducted at the end of the wet season 2010 and 16 physicochemical parameters were determined for every sample collected. Multivariate statistical techniques (cluster and factor analysis) were applied twice, first including all the sampling points, and second after the removal of deep boreholes samples. The results showed that the above methods were able to separate a mixture of processes in the aquifer system (saltwater intrusion, agricultural runoff, mineral dissolution, ion exchange, connate water influence), and spatially distribute them in the study area. They also highlighted the need for knowledge of technical information regarding the boreholes and of sound hydrogeological data in the area, since the inclusion in the analysis of deep connate groundwater masses caused masking effects.

Use of GIS and Multi-Criteria Evaluation Techniques in Environmental Problems

The application of Multi-Criteria Evaluation in combination with Geographical Information Systems in handling problems related to the environment and to spatial distribution of variables is presented through three case studies. The first one deals with the application of Boolean evaluation in siting natural wastewater treatment facilities, the second one applies both exclusionary and non-exclusionary criteria in siting a Municipal Solid Waste landfill, while the third one computes groundwater vulnerability to pollution applying non-exclusionary criteria coupled with weighted linear combination and ordered weighted averaging. Concluding, the present work highlights the advantages and the limitations of those applications in problems of siting human activities, urban development, resource allocation and management.

Water supply of Greek cities: the WFD and the principles of integrated water resources management

ABSTRACT In this paper, the water supply conditions in the major Greek cities have been investigated and a comprehensive description is provided. It has occurred that the choice of the catchment area as the administrative unit for water management purposes is rather more adapted to urban water management in Western Europe, than in Greece. In fact, while the major cities in France, Spain and the UK can be mainly supplied by water issued from the catchment area in which they are located, interbasin water transfer is necessary in Greece. The reasons are both hydrological, with the typical catchment area size in Greece being rather small, and because the economic activities of the Greek cities are not linked to rivers; so only a few of them are built on large watersheds. The reduction of water losses due to network leakage is suggested as a method for the decrease of interbasin transfer volumes.

Conceptual Model and Hydrochemical Characteristics of an Intensively Exploited Mediterranean Aquifer

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.