Challenges for Sustainable Water Resource Management: Irrigation and Salinity

Tunisia is widely considered as deficitary country in water resources, and water scarcity is evident in certain regions of the country. In the long term, this situation could become more exacerbated, considering the increased risk of aridification. However, Tunisia counts the total amount of water resources around 4860 million m3/year. Surface water resources are stressed by challenges of water quantity and quality. The distribution of these resources among the regions of the country showed the superiority of the extreme north which provides an amount of 930 million m3, despite its low area (3% of the total area). In contrast, the center and the south representing more than 75% of total national area provide only 18% of mobilizable resources. Regarding water quality, the groundwater resources are generally of low water quality. The Tunisian government has recognized the need to evolve toward a demand-oriented approach (improving overall efficiency and favoring the most productive uses of water). Moreover, great emphasis is placed on forecasting rainfall, more efficient irrigation management, and water quality (salt concentration), with the aim of increasing water use efficiency. A broad range of solutions could be considered to tackle the problems of salinization and irrigation-water scarcity. To avoid the multiple risks arising, it is important to control soil salinity and keep it below plant salinity tolerance thresholds. Nowadays large quantities of marginal water, including saline water, are still used for tolerant crops’ irrigation. Olive groves are now being fostered, as they have been found to develop more efficient physiological adaptations to cope with water and salt stress compared with alternative crops. Gaining resilience within communities was traditionally sought through water saving infrastructure. These hydrological systems have been considered as ancient techniques, for use only in semiarid Tunisian regions. The conservation of these traditional practices is however of a great importance for a sustainable development and allows considering water issues as part of life in sustainable landscapes. Investments in irrigation infrastructure in Tunisia have reached 35% of all agricultural investments along the past decades. Two-thirds of Tunisia’s irrigated area have drip or sprinkler technology for on-farm effective irrigation. In addition, the country is now expanding its program of innovative practices, including (i) artificial aquifer recharge, (ii) deficit irrigation under field conditions, and (iii) developing alternative, nonconventional resources, including treated wastewater reuse and brackish and seawater desalination.