Simulation of Seawater Intrusion in Coastal Aquifers : Forty Five-Years

Simulation of Seawater Intrusion in Coastal Aquifers: Forty Five-Years

Exploitation in an Eastern Coast Aquifer in NE Tunisia

N. Gaaloul1, F. Pliakas2, A. Kallioras3,*, C. Schuth4 and P. Marinos5

1National Research Institute for Rural Engineering Water and Forestry (INRGREF-Tunis), Tunisia

2Democritus University of Thrace, Department of Civil Engineering, Geotechnical Section, 67100 Xanthi, Greece

3National Technical University of Athens, School of Mining & Metallurgical Engineering, 15780 Zografou, Athens, Greece

4Technical University of Darmstadt, Institute of Applied Geosciences, Hydrogeology Group, 64287, Darmstadt, Germany

5National Technical University of Athens, School of Civil Engineering, Geotechnical Section, 15780 Zografou, Athens, Greece

Abstract: 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 semiautomatic

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 consider

the effects of vertical recharge on seawater intrusion, effects of boundary conditions, and effects of spatially varying

pumping from the aquifer.

Keywords: Saltwater intrusion, GIS, coastal aquifers, numerical modeling, Tunisia.

INTRODUCTION

A common problem of aquifers in the Mediterranean region

is the degradation of the groundwater quality due to

multiple stresses: excessive pumping in relation to average

natural recharge, return flow from irrigation water with intense

use of agrochemicals. In addition, drought episodes

contribute to the degradation of groundwater quality. Increasing

access to groundwater plays a key role in alleviating

poverty, stabilizing populations and reducing the need for

farmers to migrate when drought threatens agricultural livelihoods.

Many aquifer systems contain vast quantities of

saline water with limited possibilities for exploitation in urban

or agricultural supply systems, imposing added stress to

those aquifers with water of higher quality.

The research cooperation between the National Research

Institute for Rural Engineering, Water and Forestry

(INRGREF), Tunisia and the Departments of Civil Engineering

of National Technical University of Athens and Democritus

University of Thrace have presented the common

*Address correspondence to this author at the National Technical University

of Athens, School of Mining & Metallurgical Engineering, 15780 Zografou,

Athens, Greece; Tel: +302107722098; Fax: +302107722117;

E-mail: kallioras@metal.ntua.gr

experiences between some typical seawater intrusion study

areas in Greece and Tunisia. More specifically, this research

describes the main characteristics of two typical Mediterranean

coasts, in Greece (Eastern Macedonia and Thrace) and

Tunisia (Cap Bon – Eastern Coast), in terms of today’s state

of seawater intrusion conditions. In Tunisia, agriculture use

accounts

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