Modelling

Groundwater Dynamics and Seawater Intrusion in the Ras El-Jebel Coastal Plain, Tunisia

Within the project frame, a groundwater model is currently being developed for the Ras El-Jebel Coastal Plain in northern Tunisia. The plain is a typical example for an intensively cultivated coastal basin in the Arab Region, where the over-utilization of groundwater resources has led to a number of water quality- and quantity-related problems.

The alluvial aquifer in the plain covers an area of 35 km2 and is composed mainly of sand and clay. 1372 wells in the plain exploit the aquifer with extraction rates amounting to 13.5 Mm3/year. The recharge of the aquifer is estimated at 8.5 Mm3/year, which are provided by the infiltration of rainfall and excess irrigation water.

This overexploitation caused a drawdown of groundwater levels ranging from about 3m on the coast to 10m inland. Consequently the aquifer started to suffer from seawater intrusion and the water quality degraded rapidly.

The model will provide an in-depth analysis of the current aquifer dynamics as well as projected responses to different strategies for the preservation of the aquifer, including the use of artificial recharge.

The work is done in close cooperation between ACSAD, BGR and the General Directorate for Water Resources/Tunisia.