**4. Major challenges for the construction of solar desalination plants for irrigation**

The launch of desalination plants presents many major challenges. A welldetailed expertise file must be drawn up on the technical requirements [39]. There is a need to collect a lot of data for the construction of these stations. These data concern the distribution of water and its use for irrigation for better agricultural efficiency. Also, the data concern resources, both in their quantitative and qualitative aspects (rain, infiltration, flows, recharge, and water quality). This idea is shared by Margat [40] who says that desalination operations bring together a complex chain of water development and control for better energy efficiency. Indeed, when the occupation of the coast poses a problem for the installation of desalination units, the problem is "energy efficiency," which must be fully taken into account for these units coupled with thermal power stations [41]. The second major challenge is that the cost per cubic meter of water is expensive in some areas [42]. Indeed, the desalination of certain brackish water requires a fairly significant pretreatment, which can affect this cost. Since reverse osmosis desalination plants can be set up in isolated sites, another existing challenge is that these stations could significantly affect marine life and fauna [43] leading to ecological variations. For example, thermal discharges can seriously harm the marine ecosystem.

There are also steps to be taken to change consumers' perception of desalinated water, which will enable the supply of sufficient quantities of water and in fact constitute new water insurance [44]. In Tunisia, water desalination is technically feasible but at excessively high costs [45]. Indeed, there is a transfer of water from dams that mixes in aquifers to fight against seawater intrusion in coastal regions and not with desalinated water [46].

## **5. Conclusion**

Agri-food companies are emerging in countries suffering from increasing water stress. The goal is to develop agricultural production through solar water desalination. This will be one of the alternatives on which Tunisia can count for the supply

of irrigation water. The economy will flourish with the irrigation water needed for millions of hectares of arable land. However, the first and main concern is the cost of these factories that pose a problem for poor or emerging countries. Second, emissions of gas, hot water, and salinity create environmental problems. Third, using chlorine to clean membranes (reverse osmosis) creates chemical water that cannot be discharged into the sea.
