SOIL AND WATER SALINIZATION OF AN OASIS ECOSYSTEM IN THE ZIBAN REGION (TOLGA), ALGERIA

In the Ziban arid and semi-arid region of Algeria, oasis agro-ecosystems are developing at a fast pace, implying a higher demand for water supply. This has led to the secondary salinization of soil, waterlogging problem and even alkalinisation of soil. The aim of this study is to assess soil salinization and water salinity in three different oases in the Tolga region. These oases differ in terms of age, morphology, and surface state of soil. Remote sensing, analytical and statistical analyses were employed to assess the functional drainage network and degradation state of the three oases. The hydro-pedological characterisation of water and soil samples (pH, EC, calcium carbonate content) was performed through laboratory analysis. Remote sensing data and techniques were employed for the extraction of saline surfaces and land cover features. The results show that the oasis no. 3, which is located in a depression, is the most affected by salinization. Coupled with ancillary data, this outcome can be linked to morphology and the lack of an efficient drainage system. Concerning the oases 1 and 2, there is a low to no risk of salinization and waterlogging, possibly due to an efficient drainage and a favourable geomorphological setting. The two latter oases have satisfactory conditions for an efficient drainage and salt leaching. Despite the strong constraints of this Saharan context, our preliminary results suggest that the sustainable management of oasis ecosystems is achievable, providing valuable reference of the impact of climate change and human activities.