Andreas Kallioras

• Doctor of Engineering
• Professor at National Technical University of Athens

This study aimed to evaluate the impact of a wildfire on vegetation recovery and hydrological processes in a Mediterranean peri-urban system, using remote sensing and hydrological modeling. NDVI and MSAVI2 time series extracted from burned areas, control plots, and VAR-modeled plots were used to analyze vegetation regeneration. The SWAT model, cali...

The present work aims to compare two different subsurface hydrological models, namely HYDRUS and MODFLOW UZF package, in terms of groundwater recharge; thus, both models were coupled with MODFLOW. The study area is an experimental kiwifruit orchard located in the Arta plain in the Epirus region of Greece. A novel conceptual framework is introduced...

Continuous measurements of soil moisture in the deeper parts of the unsaturated zone remain an important challenge. This study examines the development of an integrated system for the continuous and 3-D monitoring of the vadose zone processes in a cost- and energy-efficient way. This system comprises TDR, ERT and GPR geophysical techniques. Their c...

Soil moisture is an essential hydrologic parameter in agricultural studies, as most services in agricultural ecosystems, such as water storage, food and fiber supply, and water and climate regulation are associated with its spatial and temporal variability. Furthermore, soil moisture is considered to be the most important soil factor for runoff and...

Groundwater modeling under pre-development state conditions is widely acclaimed as the most efficient tool, which can quantify the aquifer dynamics before manmade interventions, leading to a base from which sustainable development can be planned. While most studies focus on the application of pre-development groundwater modeling to define the rates...

Groundwater is a primary source of drinking water; however, groundwater depletion constitutes a common phenomenon worldwide. The present research aims to quantify groundwater depletion in three aquifers in Greece, including the porous aquifers in the Eastern Thermaikos Gulf, Mouriki, and the Marathonas basin. The hypothesis is to reverse the phenom...

This paper presents the investigation of groundwater vulnerability to seawater intrusion of the aquifer system in the coastal area of Laspias River, NE Greece, for the year 2023, by applying the GALDIT, SITE and SIVI methods, in the context of the groundwater management of the area. The relevant research works include the collection and analysis of...

The paper investigates the mechanism of seawater intrusion and the performance of free and open-source codes for the simulation of variable density flow problems in coastal aquifers. For this purpose, the research focused on the Marathon Watershed, located in the northeastern tip of Attica, Greece. For the simulation of the groundwater system, MODF...

This study investigated the impact of land use change on mean annual discharge in an experimental sub-basin in the metropolitan area of Athens, Greece, using the Soil and Water Assessment Tool (SWAT) model. The study site, the NW sub-basin of the Kifisos river basin, experienced an increase in artificial surfaces from 42.1 km2 in 1990 to 71.6 km2 i...

Citation: Kalaitzidou, K.; Ntona, M.M.; Zavridou, E.; Tzeletas, S.; Patsialis, T.; Kallioras, A.; Zouboulis, A.; Virgiliou, C.; Mitrakas, M.; Kazakis, N. Water Quality Evaluation of Groundwater and Dam Reservoir Water: Application of the Water Quality Index to Study Sites in Greece. Water 2023, 15, 4170. https://doi. Abstract: To detect the degrada...

Soil moisture is considered a crucial climatic parameter. Understanding and predicting variations in surface temperature, precipitation, drought, flood and the effects of future climate change need a thorough knowledge of soil moisture fluctuations. Furthermore, quantification of soil water content, one of the two variables that describe soil moist...

The hydraulic properties of the unsaturated zone, a crucial component of the pedosphere, are critical in understanding its hydrological processes, which are essential for various applications including agriculture,geotechnology, and environmental management. The saturated hydraulic conductivity (Ksat) and the correlation between volumetric water co...

Machine learning (ML) algorithms are extensively used with outstanding prediction accuracy. However, in some cases, their overfitting capabilities, along with inadvertent biases, might produce overly optimistic results. Spatial data are a special kind of data that could introduce biases to ML due to their intrinsic spatial autocorrelation. To addre...

While the observations from earth-observing satellites and in-situ weather meteorological and monitoring stations continue to expand, researchers are to deal with an abundance of data and, consequently, with a long modeling procedure. Machine learning algorithms, as universal nonlinear function approximation tools, are effective in analyzing and mo...

Managed Aquifer Recharge (MAR) is a promising technique for water management. It comprises a group of technologies that enhance the infiltration of various water sources into aquifers. The water stored underground can serve different uses, such as irrigation, industrial and drinking water supply, and the recovery or preservation of environmental as...

SWAT (Soil and Water Assessment Tool) is a continuous-time, semi-distributed, river basin model widely used to evaluate the effects of alternative management decisions on water resources. This study examines the application of the SWAT model for streamflow simulation in an experimental basin with mixed-land-use characteristics (i.e., urban/peri-urb...

Soil moisture is considered an essential climatic parameter. Knowledge of soil moisture fluctuations is deemed compulsory for comprehending and forecasting variations in surface temperature, precipitation, drought, flood, and the effects of future climate change. In addition, soil water content, one of the two variables describing soil moisture, is...

Considering the division of sources of groundwater contamination into point and diffuse, this research aims to identify the potential impact of anthropogenic activities on the aquifer system and the main water bodies of the research area. A sampling campaign was organized after the wet period during the hydrologic year of 2016. The samples analyzed...

The present study demonstrates that the use of fit-independent statistics for the evaluation of groundwater modelling results can become a useful tool for assisting regional water resources management planners, providing a deep understanding on the hydrological processes through the statistical analysis of relevant data.

Soil moisture is a hydrologic parameter of paramount importance in agricultural studies, as most services in agricultural ecosystems, such as water storage, food, and fiber supply, and water, and climate regulation, are associated with its spatial and temporal variability (Novick et al., 2022). In order to describe the state of water in the soil tw...

In this study, monthly streamflow and satellite-based actual evapotranspiration data (AET) were used to evaluate the Soil and Water Assessment Tool (SWAT) model for the calibration of an experimental sub-basin with mixed land-use characteristics in Athens, Greece. Three calibration scenarios were performed using streamflow (i.e., single variable),...

Argolis plain, one of the largest agricultural areas of Greece, is of great hydrological interest. Extensive qualitative degradation of groundwater aquifer systems, the use of Managed Aquifer Recharge technologies that started several decades ago, water infrastructure for irrigation purposes and water intended for artificial recharge and the abstra...

The identification of the hydrological processes taking place at coastal systems and the interaction between aquifers and the sea have been key features for many groundwater-related studies. However, the suitability of different boundary conditions for representing the hydrodynamic conditions along the coast in modelling applications is widely disc...

A participatory modelling approach is presented for effective groundwater management at the Mediterranean coastal plain of Marathon, Greece. The main objective was to identify groundwater problems in the area and to propose a viable groundwater management plan. Detailed investigation, using scientific literature and field work in the area, was cond...

Groundwater management of coastal aquifers is a scientific and engineering challenge, as coastal aquifer systems are hydrogeologic features that are hydraulically connected with the sea while at the same time are stressed with extensive abstraction practices for irrigation. To remedy this, Managed Aquifer Recharge -MAR- is proved to be a sound and...

SWAT (Soil and Water Assessment Tool) is a continuous time, semi-distributed river basin model that has been widely used to evaluate the effects of alternative management decisions on water resources. This study, demonstrates the application of SWAT model for streamflow simulation in an experimental basin with daily and hourly rainfall observations...

In this paper, the development of the conceptual and groundwater flow model for the coastal aquifer system of the alluvial plain of River Nestos (N. Greece), that suffers from seawater intrusion due to over-pumping for irrigation, is analyzed. The study area is a typical semi-arid hydrogeologic environment, composed of a multi-layer granular aquife...

The views and perceptions of the civil protection community have a central position in any risk management process or initiative, and are crucial to its success. However, knowledge of the views and perceptions of officials, and what affects them remains limited in the current literature. This work uses questionnaires to explore the views of civil p...

This paper demonstrates the application of a recently developed free and open-source GIS-integrated hydrochemical–hydrogeological analysis tool (named AkvaGIS) for the management and interpretation of hydrogeological data with respect to a coastal aquifer system. The aforementioned tool is composed of a geospatial database implemented in Spatialite...

Because of the spatial nature of groundwater-related data and their time component, effective groundwater management requires the application of methods pertaining to the Information and Communication Technologies sector, such as spatial data management and distributed numerical modelling. The objective of this paper is to demonstrate the effective...

MARSOL project (Demonstrating Managed Aquifer Recharge as a Solution to Water Scarcity and Drought) has taken place since 2014 to 2017 within EC FP7 call with GA 619120. In the final part of the project, first row members put together the conclusions from their personal point of view and after three years of intense research. All these statements h...

Advanced sensing technologies, combined with wireless sensor networks, have already demonstrated their value in monitoring urban water systems, where management is rather centralized within water utility organizations. Environmental water resources, characterized by more diverse stakeholders and overlapping management responsibilities of different...

FREEWAT is a free and open source QGIS-integrated platform, developed to simulate several hydrological processes by combining the capabilities of GIS for geo-processing and post-processing tools with several codes of the well-known USGS MODFLOW ‘family’. FREEWAT platform was applied for the groundwater flow simulation of a coastal aquifer system, l...

Un-managed surface and groundwater exploitation in coastal areas usually leads to deterioration of such sensitive ecosystems by means of water resources degradation and/or increased salinity. The coastal partof Marathon is a typical Mediterranean hydro-environment that hosts a naturally occurring coastal wetland linked to a typical coastal and toda...

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 o...

The management of groundwater resources in coastal environments within the Mediterranean basin has become of paramount importance, especially in the light of global changes. A typical example of such a hydrosystem is the Lavrio basin in Greece. This research site involves two aquifer types—granular and karstic formations—that are hydraulically inte...

The impact of mining activities on water resources within mined areas has certainly been a field where several studies have been conducted; yet sound quantitative approaches on such problems are mostly under-investigated in the initial steps of the planning, as the exploitation has not been started. In the present study, a groundwater flow model is...

This paper presents the updated vulnerability assessment of Xilagani - Imeros aquifer system in the coastal plain region of Rhodope Prefecture, NE Greece, in the framework of the groundwater management in the region. Information regarding the geological and geomorphological environment, as well as data concerning the hydrologic and hydrogeological...

Sound groundwater resources management is a matter of paramount importance in Circum-Mediterranean, for the ecologic status of the underlying aquifer systems. Freshwater resources in Greece are identified within all types of aquifer formations, however two distinct types are the ones that draw the attention of the scientific and the engineering com...

Groundwater resources assessment has resulted in development of models that help identify the vulnerable zones. This paper presents a GIS-based hydrogeological index, named GALDIT, aiming at the assessment of aquifer vulnerability to seawater intrusion in Atalanti coastal aquifer, Central-Eastern Greece. The above acronym is formed from the most im...

ion of groundwater resources in the coastal aquifer system of Argolis is investigated since the late 1950’s. The increasing water demands due to the agricultural development of the area (mainly citrus trees) during the last years, in combination with the touristic growth, has led to the overexploitation of groundwater resources of the coastal aquif...

FREEWAT is an open source and public domain GIS integrated modelling environment for the simulation of water quantity and quality in surface water and groundwater with an integrated water management and planning module. It involves the integration of: (i) Observation-Analysis Tool (OAT) that combines a number of time-series processing functionaliti...

Managed Aquifer Recharge is a wide-spread well-established groundwater engineering method which is largely seen as sound and sustainable solution to water scarcity hydrologically sensitive areas, such as the Circum Mediterranean. The process of site selection for the installation of a MAR facility is of paramount importance for the feasibility and...

Determining the hydrogeochemical processes has always been a challenge for scientists. The aim of this work is the study of the principal hydrogeochemical processes controlling groundwater quality in the Marathon coastal plain, Greece, with emphasis on the origin of the solutes. Various physicochemical parameters and major ions of twenty-five groun...

This paper presents the updated vulnerability assessment of Xilagani - Imeros aquifer system in the coastal plain region of Rhodope Prefecture, NE Greece, in the framework of the groundwater management in the region. Information regarding the geological and geomorphological environment, as well as data concerning the hydrologic and hydrogeological...

This paper deals with the hydrogeological study of the evolution of groundwater salinisation - degradation at the eastern Nestos River Delta. Relevant field works including in-situ measurements of groundwater level, pH, Specific Electrical Conductivity (SEC) and temperature took place in the years 2008 and 2009. Groundwater samples were also collec...

Managed Aquifer Recharge is a wide-spread well-established groundwater engineering method which is largely seen as an alternative potential major source for water and this conclusion becomes even more pronounced in semi-arid and/or arid areas, such as the Mediterranean Basin. The process of site selection for the installation of a MAR facility is o...

Groundwater resources assessment has resulted in development of models that help identify the vulnerable zones. This paper presents a GIS-based hydrogeological index, named GALDIT, aiming at the assessment of aquifer vulnerability to seawater intrusion in Atalanti coastal aquifer, Central-Eastern Greece. The above acronym is formed from the most im...

Sound groundwater resources management is a matter of paramount importance in Circum-Mediterranean, for the ecologic status of the underlying aquifer systems. Freshwater resources in Greece are identified within all types of aquifer formations, however two distinct types are the ones that draw the attention of the scientific and the engineering com...

Precise measurements of the downward movement of precipitation through the unsaturated zone, as well as return flow of moisture to the atmosphere via evaporation, have always been challenging in regard to in-situ monitoring techniques. This study investigates the profile of volumetric water-content fluctuations within the unsaturated zone through a...

In arid regions like the Arabian Peninsula, available water resources are essentially restricted to groundwater, requiring a detailed understanding of the local and regional hydrogeological conditions and water budgets. In the framework of the IWAS initiative, the 1.8 × 106 km2 large sedimentary Upper Mega Aquifer of the Arabian Peninsula was chose...

This paper contributes to the investigation of the unsaturated zone, through the application of combined field and lab techniques. The results show that direct push methods, which are considered ideal for multilevel sampling of undisturbed soil in the unsaturated zone, proved to be effective also for the consequent extraction of the pore water for...

In this paper, the application of the framework DPSIR is presented in Nea Peramos, Kavala, coastal surface plain and aquifer system. The procedure included the use of previous relevant hydrological, hydrogeological and management studies, regarding the study area. The development of the framework DPSIR, recognizing and visualizing in a simplified m...

A tailored geophysical investigation was designed to provide useful information in two of the activities/priorities of the Lavrion Technological and Cultural Park (LTCP): a) identification of optimal location for the construction of an advanced Soil-Aquifer-System (SAT) which will be used to monitor geo-purification processes within the unsaturated...

The research investigated boron variability in space and time, using 450 groundwater samples from 75 representative wells in the Safwan–Zubair area of Basra district, South Iraq, collected monthly from January to June 2000, with also 75 soil samples from selected farms in the same area. Minimum and maximum values of boron concentrations range from...

Groundwater resources of karst aquifers within Circum-Mediterranean are a vital natural resource, which have been exploited since the dawn of the Mediterranean civilization. In Greece, carbonate formations are thought to be one of the most important sources for various water uses, that are vital for the country’s economy and development, that is ag...

This paper presents the study of the impact of precipitation changes on alluvial aquifer systems in Xanthi Prefecture plain region, Greece. Two study areas were investigated, taking into account several hydrological and hydrogeological data for a time period of 23 years (1989-2011) measured and elaborated in the framework of the hydrogeological con...

Processes such as urbanization, agricultural development and industrialization have led to increasing demand of groundwater resources resulting in pollution threats to groundwater in different ways, either as contaminant loads on the ground surface, or as seawater intrusion due to overexploitation of wells in the coastal zone. Two groundwater vulne...

Groundwater within coastal aquifers is considered a very sensitive natural resource since its quantity and quality is threatened by anthropogenic activities as well as global and climate changes. The major environmental hazard with respect to coastal aquifers is the phenomenon of seawater intrusion, which is even more pronounced in the Mediterranea...

A reconnaissance geophysical survey is a starting task of a multitasking collaboration to detect all hydrogeological (extent of salinization), stratigraphical, geological features of Thoriko valley in order to reconstruct the environment in ancient times as well as to interpret the position of the various archaeological monuments existing in the ar...

This paper analyses land degradation phenomena at the SE part of R. Nestos Delta, Greece. The work includes geological, hydrological and hydrogeological data interpretation in the study area, including field and laboratory measurements and soil samples analyses during 2007, 2008 and 2009. The study also involved the correlation of certain soil para...

Groundwater within coastal aquifers is considered a very sensitive natural resource since its quantity and quality is threatened by anthropogenic activities as well as global and climate changes. The major environmental hazard with respect to coastal aquifers is the phenomenon of seawater intrusion, and is more pronounced in the Mediterranean basin...

More than 5,000 years before today, the Dilmun culture was developed on the island of Bahrain, with important trading activities which were taking place during the antiquity. This blossom of civilization and development was most probably due to-among others-the existence of the well-known Dilmun springs. According to the Gilgamesh epic, it was Enki...

Southern Europe and the Mediterranean region are facing the challenge of managing its water resources under conditions of increasing scarcity and concerns about water quality. Already, the availability of fresh water in sufficient quality and quantity is one of the major factors limiting socio-economic development. Innovative water management strat...

Seawater intrusion is a widely occurring environmental problem, which concerns the majority of the coastal aquifers in the world, having large negative impacts - from an economic, developmental, environmental as well as social point of view - on the coastal local communities. The fact that almost 40% of the world's population lives within a distanc...

Managed Aquifer Recharge is a wide-spread well-established groundwater engineering method which is largely seen as an alternative potential major source for water and this conclusion becomes even more pronounced in semi-arid and/or arid areas, such as the Mediterranean Basin. The process of site selection for the installation of a MAR facility is o...

This study focuses on the engineering design of a Soil-Aquifer Treatment (SAT) system for the artificial recharge of the coastal aquifer system of River Nestos eastern delta area, as a method to countermeasure seawater intrusion and groundwater/soil salinization. The design of such a groundwater engineering project recharging effluent from the near...

The necessity for accurate determination of groundwater recharge is an important issue for the “smart mining” of groundwater resources, especially in hydrologically sensitive regions. Different techniques and methods have been widely reported in literature, and isotope hydrology has found to be one of the major fields of the study. This paper prese...

The Mediterranean region is one of the most imperilled regions in the world concerning present and future water scarcity. The region is delicately positioned at the crossroads between East and West, interlinking Europe, Asia and Africa. Societal and economic changes causing population growth, industrialisation and urbanisation lead to significant i...

River Evros is a transboundary river flowing through Bulgaria, Greece and Turkey and coincides with the borderline among them for a considerable part of its length in the downstream part of its basin. River Evros is historically engaged to a long series of serious and devastating flood events with high socio-economical costs and environmental impac...

Management of groundwater resources involves the allocation of groundwater supplies and water quality to competing water demands and uses. The resource allocation problem is characterized by conflicting objectives and complex hydrologic and environmental constraints, especially in coastal aquifers. The development of mathematical simulation models...

This paper contributes to the investigation of the unsaturated zone, through the application of combined field and lab techniques. The results show that direct push methods, which are considered ideal for multilevel sampling of undisturbed soil in the unsaturated zone, proved to be effective also for the consequent extraction of the pore water for...

According to the latest IPCC projections, the Circum-Mediterranean region will be particularly affected by Global and Climate Change. These changes include population growth, increases in food, water and energy demands, changes in land use patterns and urbanization/industrialization, while at the same time, the renewable water resources in the regi...

Sperchios river basin covers an area of 2116 km2, with an average altitude of approximately 810 m, while the river is recharged by many streams of permanent and periodic flow. The high gradients which are present within approximately 2/3 of the total length of the river course form a rather mountainous topography -streamy, with crucial flooding pea...

As concluded in the relevant UN Convention in 1994, desertification has affected large areas within the European Mediterranean coastal regions and is threatening even larger territories. Desertification as a means of land degradation can be resulted from a series of factors including climatic changes and anthropogenic activities; while appears more...

Mediterranean basin is considered as being highly susceptible to climate changes, especially as arid and semi-arid climate conditions as well as periodic draughts have caused a series of water-related rising problems. This issue becomes more pronounced in coastal river basins, which usually suffer major anthropogenic pressures such as growing water...

For groundwater resources management in arid environments the rate of aquifer replenishment due to groundwater recharge is one of the most important factors and unfortunately also one of the most difficult to derive with sufficient accuracy. In general, the potential evaporation by far exceeds the precipitation limiting groundwater recharge. Unsat...

For the determination of groundwater recharge processes in arid environments, vadose zone water fluxes and water storage should be considered. To better understand and quantify vadose zone processes influencing groundwater recharge, a soil column experimental setup has been developed that mimics arid atmospheric conditions and measures water and te...