Andreas Kallioras

Simulation of Seawater Intrusion in Coastal Aquifers: Forty Five-Years Exploitation in an Eastern Coast Aquifer in NE Tunisia

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 provides groundwater planners with quantitative techniques for analyzing alternatives groundwater resources management. The gathered knowledge was then used to build and to calibrate a 3D transient model of 45 years time period (1963-2008). The numerical model was used further to discuss some issues on the management of the regional groundwater resources. The calibration of the 3D model has been achieved in a time dependent, iterative and semi- automatic fashion. This paper describes a 3-D seawater intrusion modeling process for a specified study area in Eastern Coast aquifer, in NE Tunisia. The simulation results presented in this paper are based on the density-dependent miscible flow and transport modeling approach for simulation of seawater intrusion in coastal aquifers. Response evaluations con- sider the effects of vertical recharge on seawater intrusion, effects of boundary conditions, and effects of spatially varying pumping from the aquifer.

Groundwater vulnerability assessment at SW Rhodope aquifer system in NE Greece

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.

Water resources assessment and management of karst aquifer systems in Greece

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 agriculture and water supply. In most cases, they are considered as integral parts of some of the most strategic hydrosystems in Greece, containing surface water and groundwater resources that secure water supply for several anthropogenic activities. This paper provides a review of different aquifer types in Greece (granular and karstic), focusing on karst hydrosystems. It presents their spatial distribution throughout the entire Greek territory, and describes the most important environmental stresses upon them, while it analyzes their importance and role to the country’s water supply. Finally, this study analyzes the river basin of (Central Greece), used as a reference hydrosystem, to prove the ample importance of karst reservoirs in Greece.

The Riddle of the Springs of Dilmun—Does the Gilgamesh Epic Tell the Truth?

Introduction About 5200 years ago, the Dilmun culture (3200 to 330 B.C.) developed on the island of Bahrain in the Persian Gulf (Figure 1) (Bibby 1996). The name Dilmun appears on some of the earliest written documents in the world; these are clay tablets inscribed with an experimental version of cuneiform which was to become the dominant script of the ancient Middle East from about 3000 B.C. (Crawford 1998). Dilmun was considered to be a pure and sacred place by the ancient Sumerians, a kind of earthly paradise where gods and heroes enjoyed immortality (Crawford and Rice 2000). In the Gilgamesh epic Dilmun is described as a heavenly land, a place of the everlasting youth; a holy place without illness and death. In ancient times Dilmun was mainly known for the trading activities that were taking place in the region. The Epic of Gilgamesh, which dates from the 3rd Millennium B.C. (Sandars 1972), is one of the finest surviving epic poems in world literature. The existence of the Epic has been known to the modern world for only the last 120 years, since shortly after the decipherment of cuneiform writing (Kovacs 1989). In its complete state the Epic comprises about 2900 lines written on 11 clay tablets. George (1999) mentions that it was miraculously preserved on clay tablets dating back as far as 4000 years. The Epic relates the story of Gilgamesh’s—King of Uruk—adventures with the wild man Enkidu and of his arduous journey to the ends of the earth in quest of the Babylonian Noah and the secret of immortality. Jackson (1997) in his translation of Gilgamesh Epic refers to Dilmun as a “paradise regained;

Methods to Countermeasure the Intrusion of Seawater into Coastal Aquifer Systems

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 distance of 80 km from the coastline gives rise to the significance of the aforementioned problem and emphasises the necessity for its prevention. This chapter analyses the engineering, managerial as well as techno-economical aspects with respect to the prevention of seawater encroachment into freshwater coastal aquifers and presents some state-of-the-art methods that are currently applied worldwide. It provides a critical review of the application of different type of coastal barriers (either by hydraulic, biological or construction means), management of aquifer recharge (through the application of underground or surface artificial recharge techniques), control of groundwater abstraction and exploitation scheme (by means of suggesting the optimal allocation of abstraction areas for minimising the risk of further intrusion) and other methods of prevention. Finally, this chapter investigates the current enacted legislation as well as adopted policy – mainly developed at a European level – with respect to the prevention of seawater intrusion, together with all the observed gaps and problems which create difficulties for its enforcement.

Application of SWOT analysis for the management of transboundary River Evros (Bulgaria, Greece, Turkey)

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 impacts on the riparian communities and even on the national economies of the three neighbouring countries which share the area of its hydrological basin. Besides, there have been a number of serious groundwater pollution incidents which have been identified at certain parts of the basin. Thus, the environmental problems encountered in the river’s basin, represent both quantitative and qualitative ones. This paper investigates the main reasons for the faced transboundary environmental, socio-economic and developmental problems engaged to the functioning of the River Evros natural system and its management, based on a SWOT analysis (acronym which stands for strengths, weaknesses, opportunities and threats). The ultimate goal of the investigation is to make sound conclusions, acting as a tool which may well facilitate a, badly needed, rational and integrated management of the entire transboundary surface and groundwater resources of the River Evros system (main river and its tributaries).

Hydrodynamic analysis of a Mediterranean aquifer system with the use of hydrochemical and isotopical analysis as supporting tools

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 interconnected. Furthermore, the proximity to the sea and the abstractions for irrigation and drinking water supply have led to the phenomenon of seawater intrusion. The present study aims at analyzing the hydraulic, hydrological, and hydrogeological conditions of the area by means of hydrochemical and isotopical data interpretation as supporting tools, which will inform and support the development of an integrated conceptual hydrogeological model of the area. Field investigations were conducted in order to collect piezometric and chemical data and use them to retrieve the quantitative and qualitative status of the local aquifer units. New interpretation of an older dataset gave an insight into how the karstic aquifer behaves in terms of hydraulics. The results have also demonstrated that there is a hydraulic connection between the different aquifers and the Mediterranean Sea, while natural recharge was quantified for both aquifer types.

SPECIAL ISSUE PREFACE - “Groundwater Resources Management in Coastal Regions”

Management of groundwater resources is a key issue for countries which are located within sensitive hydrologic or hydrogeologic basins, playing a vital -or centralrole in sustainable development, as well as on the long-term geopolitical stability. Coastal countries and more specifically coastal aquifers are considered as such sensitive regions. The fact that groundwater is one of the most important freshwater resources on earth, with almost 90% of available freshwater quantities found in hydrogeologic systems, makes the management of groundwater resources an issue of paramount importance. With this special issue, we wish to initiate an open discussion or platform, which will contain different approaches for the managament of groundwaters in such hydrollogically sensitive regions. Sensitivity lies on both quantitative as well as qualitative characteristics of the region, including the majority of environmental water problems such as: groundwater contamination and pollution, aquifer overexploitation, seawater intrusion, groundwater-surface water interactions and management of water resources.