Tayeb Nouri

The progressive silting up of dams in arid and semi-arid zones is a major problem, affecting storage capacity, the durability of hydraulic structures, and the sustainable management of water resources. In this context, the Brézina Dam, located in the El-Bayadh province (southwest Algeria) and with a capacity of approximately 123 million m³, was studied to characterize the morpho-sedimentary evolution of the catchment and reservoir over the period 2000–2025. The methodological approach is based on the spatio-temporal analysis of multi-date Digital Terrain Models (DTMs) using Google Earth Engine (GEE) and the calculation of the ?DTM, allowing for the identification and quantification of erosion and sedimentation zones. Descriptive and inferential statistical indicators, combined with automated thematic maps, were used to analyze topographic variations and estimate sediment volumes.The results highlight a dynamic dominated by sedimentation, with variations in the DEM (Digital Elevation Model) ranging from ?12 to +25 m and a statistically significant average increase in elevation (t ? 28.04; p < 10?¹?). Sedimentary deposits are mainly concentrated in valleys and near the dike, particularly in the 900–910 m elevation range observed in 2025. Volumetric analysis indicates that 59.54% of the surface area is affected by low-intensity sedimentation, compared to 31.42% affected by erosion, with an estimated eroded volume of 3.92 million m³ and a net positive sediment budget of +8.81 million m³.Beyond the hydraulic challenges, these results highlight the potential for valorizing dredged mud as organo-mineral amendments to improve the structure, water retention and fertility of sandy soils in arid areas, thus contributing to integrated and sustainable management of dams and agricultural systems. Keywords: Siltation, valorization, erosion, sedimentation, remote sensing, dam.

Small hill reservoirs in arid North Africa face accelerating threats from soil erosion and siltation, yet integrated assessments linking erosion dynamics, water quality, and soil fertility remain scarce. This study presents a multi-component geospatial assessment of the 345 km² Es-Sabba watershed in the Saharan Atlas of southwestern Algeria. Soil loss was quantified using the revised universal soil loss equation (RUSLE) integrated with Sentinel-2 imagery, a 30 m digital elevation model (DEM), and GIS analysis for 2016–2025. The mean annual soil loss reached 26.3 t/ha/yr, with 68.4% of the watershed under high-to-severe erosion; topography and vegetation cover were the dominant controls. Estimated sediment delivery to the reservoir is 135,300 t/yr, projecting a functional lifespan of 11–15 years without intervention. Hydrochemical analysis classified reservoir water as alkaline- and sulfate-rich, yet suitable for irrigation with very low sodicity risk (sodium adsorption ratio, SAR = 0.08) and an excellent Irrigation Water Quality Index (IWQI = 91.75). Soils exhibited low-to-moderate fertility (mean soil fertility index, SFI = 0.416), with widespread nitrogen deficiency constraining vegetation-based erosion control. The integrated framework identifies circular-economy opportunities through nutrient-rich sediment reuse and provides actionable guidance for climate-resilient reservoir management in arid catchments.

The Atlas pistachio tree (Pistacia atlantica) is a woody deciduous species from the family Anacardiaceae. It thrives in the steppe plains and Saharan Atlas of the Naâma region in south-western Algeria. This tree is well known in traditional Algerian medicine for its active phenolic compounds, particularly those found in its seeds and leaves. To promote its use, an ethnobotanical survey was conducted among herbalists and other knowledgeable individuals in the Naâma region, utilizing 100 questionnaires divided among 25 municipalities. The findings revealed that leaves (42%) and fruits (31%) are the most commonly utilized parts. The predominant preparation methods include decoction and grinding, but also other forms are popular, such as herbal tea or powder mixed with honey, dates, milk, or water. Administration is mainly oral, though external applications are also common, particularly for localized issues. The most frequently treated conditions include oral diseases, stomach ulcers, respiratory infections, Malta fever, and skin rashes, with values of fidelity index ranging from 2% to 14%. Most reported outcomes from these treatments are positive, indicating either cures or improvements. The frequency of use for this plant among the respondents is 100%, underscoring its significant cultural importance. The informant consensus exceeded 0.70, reflecting a robust therapeutic understanding of the plant. The global knowledge index regarding its uses is notably high, highlighting its essential role in the community for medicinal and other applications.