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Title: SIMULATION OF SEAWATER INTRUSION IN COASTAL AQUIFERS: SOME TYPICAL RESPONSES (PLAIN OF GROMBALIA NORTHEAST OF TUNISIA)

Author: N. Gaaloul and A. Soussi

Year: 2009

Publisher: European Water Resources Association (EWRA)

Description:

The underground waters represent an important resource exploited for human consumption and for agricultural and industrial use. Those waters are usually contaminated by pollutants of different natures: biological, chemical, or physical. Prevention against the aquifer pollution constitutes an important stage, to which scientists are providing with making an increasing effort, especially by studying the aquifer vulnerability. Seawater intrusion in coastal aquifers is generally three dimensional (3-D) in nature. This paper presents some typical example simulations of 3-D seawater intrusion process for a specified hypothetical study area. The simulation results presented in this paper are based on the densitydependent miscible flow and transport modelling approach for simulation of seawater intrusion in coastal aquifers. A nonlinear optimization-based simulation methodology was used in this study. The phreatic aquifer of Grombalia (prefecture of Nabeul, northeastern coast of Tunisia), which occupies an area of 363 km2, has a great economical importance, because it is used for irrigation and domestic consumption. The area of the aquifer is essentially occupied by agricultural zones, characterised by increasing use of chemical fertilizers. Various steady state simulations are performed for a specified study area. Response
evaluations consider the effects of vertical recharge on seawater intrusion, effects of boundary conditions, and effects of spatially varying pumping from the aquifer. The 3-D simulations demonstrate the viability of using a planned strategy of spatially varying withdrawals from the aquifer to manage seawater intrusion. It is demonstrated that series of pumps near the ocean-face boundary induce a hydraulic head distribution that can be effectively used for controlling seawater intrusion.