Adapting to water scarcity and climate change in Mediterranean regions: contribution of the 3D- FEFLOW salinity transport model in the island of Jerba, southeast Tunisia

Contenu

Titre

Adapting to water scarcity and climate change in Mediterranean regions: contribution of the 3D- FEFLOW salinity transport model in the island of Jerba, southeast Tunisia

Auteur

Hedoin, Jérémie

Lachaal, Fethi

Collignon, Bernard

Date

2019-09-24

Résumé

The shallow aquifer of Jerba Island is particularly sensitive to sea level rise (SLR) because the island's relief is very moderate and the altitude of the piezometric surface is close to zero. Seawater intrusion is widespread along the coast, but its amplitude varies from one area to another, depending on the groundwater abstraction rate induced by different economic patterns.
The freshwater lens found in the eastern part of the island is likely protected by infiltration from the return of irrigation water and some wastewater. The aquifer water balance is artificial: fresh water import from the continent and desalinated water account for 400% of rainfall infiltration.
In this study, we are digitally studying the impact of sea level rise (SLR) through the implementation of a 3D-FEFLOW salinity transport model for the shallow aquifer on Jerba Island. Changes in groundwater and sea water intrusion have been estimated under various climate change scenarios (RCP 8.5 and 4.5). Recharge, abstraction, discharge into the aquifer, precipitation and groundwater requirements were projected under the same scenarios. For each scenario, piezometric and salinity maps were simulated for the years 2030, 2050 and 2100.
Simulations in the model show that the Jerba aquifer is especially sensitive to any increase in groundwater abstraction or decrease in water import and/or desalination. With an increasing water demand on the continent, it may become difficult to ensure a stable volume of freshwater imports from the continent. In this case, the survival of the freshwater lens will depend on increased use of non-conventional resources (treated sweat and desalination). This will be an essential element in preserving the orchards (palm and olive trees) and tourist activities that form the basis of the island's economy.

Langue

eng