Belkacem Boumaraf

Multisource remote sensing data is utilised for the purpose of monitoring annual and interannual changes associated with climate change in the water bodies of the Chotts of Merouane and Melrhir, which are located in the Zone of Chotts in North Africa. These endorheic depressions are distinguished by recurrent flooding events of varying magnitude and frequency, which are contingent on fluctuations in climate parameters. It has been determined that certain cities located within the surrounding watersheds, such as Biskra, are subject to the intermittent threat of severe flooding. This has been shown to result in land degradation and soil salinisation during the drying-up process. A detailed examination of chronological data from the 1960s onwards reveals a decline in the frequency of flooding in Chott Melrhir in recent years. It is noteworthy that the region has not experienced any substantial flooding since 2020. This phenomenon is concomitant with the marked decline in precipitation levels observed in the region. Since 1980, there have been at least ten significant floods, resulting in varying degrees of damage and disruption. In contrast, Chott Merouane exhibits a more consistent hydrological pattern, with water flowing almost year-round due to wastewater and the drainage of the palm groves by the Oued Righ. Until the 1970s, the occurrence of flooding in the region was exclusively attributable to the direct overflow of the Biskra River and its tributaries. However, from the 1980s onwards, a new type of flooding emerged, linked to insufficient infiltration and drainage capacity in the soil and sewage systems during rainfall that was sometimes considered normal. The hydrological regime in the area has severe ramifications for the water supply and the state of the oases, which are vulnerable to salinisation.

Over the past decades, the Ghouts—as an oasis system recognized by the FAO as a Globally Important Agricultural Heritage System—have experienced significant degradation caused by climate change and water overexploitation. This degradation has serious socio-economic consequences: it threatens food security and the primary sources of livelihood for the local population, increasing their overall vulnerability. Studies have focused on the driving factors behind drought phenomena and water and soil-related constraints without establishing a clear link between these factors and the Ghouts degradation. Conducting an in-depth investigation is crucial to preserving this global agricultural heritage system. This research aims to analyze land use/land cover (LULC) changes in El Oued Valley (southeastern Algeria), based on the spatiotemporal dynamics of Ghouts, to identify the factors driving their degradation and the potential future scenarios using Geographic Information System (GIS). Artificial neural network (ANN) and cellular automata (CA)-based models were employed to predict Ghouts evolution. The findings reveal that El Oued is the most vulnerable municipality, having undergone a dramatic reduction of 89.3% in Ghout number. This decline is mainly due to the drought phenomenon, significant urban expansion (+ 2300 ha), and modern cultivations spread (+ 304.2 ha). The predicted LULC maps indicate a continued reduction in the Ghout, with about 62 hectares expected to be replaced by built-up areas and modern agricultural systems. By 2050, only 48 healthy Ghouts are expected to remain, primarily on the western and eastern sides of the city. The adoption of agroecological practices, sustainable water management, and valorization initiatives should be promoted by local stakeholders as effective strategies for the future preservation of Ghouts.

During this study, our objective was to systematically identify predominant spatiotemporal trends related to the evolution of agricultural perimeters in a Saharan region, specifically the oases of Oued Righ in Algeria. To achieve this, we used satellite imagery data. The chronological sequence of satellite images covering the Oued Righ region, situated in the Northeastern Sahara of Algeria, was meticulously established. Spatial remote sensing proved to be an essential tool, providing us with up-to-date and geo-referenced data regarding vegetation. We used a time series of Landsat (8, 4-5, 7) and Sentinel 2 images covering Oued Righ from 1984 to 2024, using bands 4, 3, 2, and 5, 4, 3 infrared. These images offered precise insights into the actual vegetation development in the study area, eliminating any guesswork. Our analysis relied on vegetation indices, notably the NDVI (Normalized Difference Vegetation Index), allowing us to objectively and scientifically monitor the evolution of this perimeter.

Agricultural residues are generated during the production and processing of agricultural crops. Under modern date palm plantation practices, field operations generate huge quantities of residues, which are discarded with little valorization. The date palm agro-industry produces significant amounts of waste. The accumulation of these residues can cause ecological damage to the oasis ecosystems. There is a lack of comprehensive data on long-term research studies that aim to assess the impact of date palm waste management practices. Composting and/or pyrolysis of date palm residues showed benefits for improving soil physical and chemical properties, particularly in sandy soils. This claim holds particular significance for arid and semi-arid regions, which are characterized by low fertility and are susceptible to soil degradation, accentuated by ongoing climate change. This review summarizes the existing literature concerning the valorization of date palm residues with regards to compost and pyrolysis processes, as well as the impact of their application on soil quality. Further research is required to assess the effects of using date palm residues for better soil amendment management. Research should focus on composting and biochar technologies for date palm residues and their application in arid and semi-arid regions to combat soil erosion and degradation. Increasing the beneficial uses of date palm residues could lead to sustainable and economic growth in dry areas.

Generally, soils of arid and semi-arid regions have low water retention properties due to high sand and low organic carbon contents. This study aimed at quantifying the effect of date palm-based organic amendments (OAs) on the water retention properties of two soils (sandy loam and silty loam), as well as the influence of sand supplementation (0.5–2 mm) on the magnitude of the effect of OAs. Different grain size distributions were obtained by adding sand to natural soils. For this purpose, sand was added to the two soils (1/3 and 2/3) and different soil-OA combinations were tested at a dose of 3% by mass: compost alone, biochar alone and a mixture of biochar and compost (50:50 in mass), in addition to unamended control soils. Soil water contents were measured at nine matric potentials ranging from the saturation to the permanent wilting point. Biochar was more efficient than compost at improving soil water retention. The effect of organic amendments on water retention increased with sand content. In most cases, soil water content values were significantly higher for biochar-amended soils than for unamended or compost-amended soils. The weakness of the effect of compost addition (if alone) was probably due to its properties and notably its high mineral content and electrical conductivity. Soil sand supplementation led to higher differences between the OA-amended soils and unamended soils. Changes in available water capacity reached +26% and +80% in a sandy loamy soil enriched with 2/3 sand and amended with compost and with biochar, respectively, compared to the unamended soil. These results show that sand content (and more generally, soil texture) influences the effect of OA application. Thus, the application of biochar from date palm residues in soil seems to be an effective solution to improve the water retention properties of coarse textured soils and contribute to optimizing the use of water resources in irrigated areas.

Gypsum is the most abundant mineral in the soils of arid regions, it forms when the concentrations of Ca+2 and SO4-2 are considerable in the soil and has an enormous influence on their physico-chemical properties. Several representative profiles on a sequence in the Ziban region (northeast of Algeria) were studied. The results obtained indicate that several forms of gypsum are distributed according to the physico-chemical characteristics of the soils. The formation of gypsum is geological in the upper levels and of neoformation in the lower part of the plain towards the depression of Oumach this is due to the proximity of the water table.