In recent decades, water pollution has become a major concern, threatening both humans and natural ecosystems. This study aims to analyze seasonal variations in the quality of surface water of the Nador Canal in Morocco, using the water quality index (WQI) and principal component analysis (PCA). Surface water samples from 22 sites along the canal were analyzed for physical, chemical, and heavy metal parameters. The results of the study revealed significant seasonal variations, with water quality decreasing in the summer months, while its quality generally improved in winter. The predominant water type was Na⁺-Cl⁻ in summer, while it was the mixed Ca²⁺-Na⁺-HCO₃⁻ water type in winter. WQI values also varied seasonally, with an average of 113.04 in summer and 160.6 in winter, classifying the water as unsuitable for drinking but suitable for irrigation throughout the year. The results of the water quality index are consistent with the results of the principal component analysis of surface water in the Nador Canal, where the results of the principal component analysis showed that there are significant seasonal variations in water quality. In both summer and winter, major ions like magnesium, sodium, and calcium predominantly indicate influences from natural and anthropogenic sources. In winter, heavy metals and nutrients, signaling pollution from industrial and agricultural runoff, become especially prominent. These variations are influenced by rainfall patterns and agricultural runoff, emphasizing the need for adaptive water management practices to maintain crop and soil health. This study provides new insights into the dynamic interplay between seasonal factors and water quality, offering valuable guidance for local water resource management.

Le lac Sidi Ali est un lac naturel d'altitude (2070-2080 m), sans exutoire superficiel, déterminé par le barrage d'une coulée basaltique. Doté d'un bassin versant apparent de 15,6 km², il est alimenté par des eaux de ruissellement et par des sources karstiques. Son niveau subit des variations très fortes, annuelles et interannuelles, sous le contrôle des conditions climatiques, et en particulier des pluies et de l'évapotranspiration. Les périodes de sécheresse qui ont marqué les trois dernières décennies, se sont traduites par un abaissement du niveau de près de 7 m. Mais les précipitations abondantes des années 2008-09 et 2009-10 ont provoqué une nette remontée. Une régression multiple d'assez bonne qualité ( r = 0,87) lie la variation annuelle du niveau (d'août à août) à différents paramètres (conditions climatiques et niveau initial du lac).

Climate change, drought, erosion, water contamination resources, desertification, and loss of soil quality represent major environmental risks worldwide. Facing these risks is the most important issue for sustainable development. Conventional tillage (CT) practices seem to expose the soils of semi-arid regions, which are initially fragile, to degradation that is accentuated by the overuse of the environment. The benefits of conservation agriculture (CA) could mitigate the degradation of natural resources, particularly soils. The adaptation and transfer of the no-till (NT) system with mulch open new perspectives for the development of agriculture in semi-arid regions. The main objective of this study is to assess the impact of conservation agriculture, especially no-till (NT) system, on the physical properties of soil (structural stability (SS), bulk density (BD), gravimetric water content (θg), and soil organic matter (SOM)) compared to conventional tillage (CT). The main changes associated with the transition from a CT system to an NT system were evaluated at the experimental site, Merchouch (M13), which is typified by vertisol soil, and at the Ain Sbit (AS7) site, which is characterized by isohumic soil. Under a no-till system, most of the physical properties of the soil were improved in both sites, with a clear difference in the M13 site. Structural stability under NT showed a significant increase in both sites (fast wetting (FW), slow wetting (SW), and wet stirring (WS) improved by 88, 43, and 83% at the M13 site, respectively, against, 16, 23, and 7%, respectively, at the AS7 site). On the other hand, the SOM increased from 2.0 to 2.6% (an improvement of 28%) at AS7 and from 1.2% to 1.9% (an improvement of 52%) at M13. This research demonstrated that conservation agriculture, especially NT, improves the soil physical quality in both medium and long terms, confirming its suitability for the climatic and edaphic constraints of semi-arid areas in Morocco as well as in other parts of the world.