The study of land use and land cover change (LULC) is essential for the development of strategies, monitoring and control of the ecosystem. The present study aims to describe the dynamics of land cover and land use, and specially the impact of certain climatic parameters on the distribution of vegetation and land cover. For this study, multi-temporal remote sensing data are used to monitor land cover changes in Morocco, using a set of Landsat images, including Landsat 7 (ETM+), Landsat 5 (TM), and Landsat 8 (OLI), captured during the period 2000-2020, those changes were determined by adopting the maximum likelihood (ML) classification method. The classification results show good accuracy values in the range of 90% (2000), 80% (2007), 82% (2010), 93% (2020). The LU/LC change detection showed a decrease of agricultural and forest areas in the order of 5% between the year 2000 and 2020, and an increase of bare soil of 5% to 6%, and a notable change in urban area from 97.31 ha (0.03%) in 2000 to 2988.2637 ha (0.82%) in 2020. The overall results obtained from LULC show that the vegetation cover of the study area has undergone major changes during the study period. In order to monitor the vegetation status, an analysis of the precipitation-vegetation interaction is essential. The normalized difference vegetation index (NDVI) was determined from 2000 to 2020, to identify vegetation categories and quantify the vegetation density in the Lakhdar sub-basin. The obtained NDVI was analyzed using climatic index SPI (Normalized Precipitation Index) based on rainfall data from five stations. The correlation study between NDVI and SPI indices shows a strong linear relation between these two indicators especially while using an annual index SPI12 however, the use of NDVI index based on remote sensing provides a significant result while assessing vegetation. The results of our study can be used for vegetation monitoring and sustainable management of the area, since it is one of the largest basins in the country.

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Purpose. The Bou Azzer Mine encounters difficulties during cobalt mining. In order to select the optimal mining sequence with the least geotechnical stability problems, one possible variant is the cut and backfill mining method used in the Bou Azzer East area at a depth of 540 m. Methods. This paper presents a methodology for selecting a sequence of the cut and backfill mining method using 2D geotechnical numerical modeling, taking into account the morphological characteristics, geomechanical properties of the ore and the surrounding rocks. Findings. The sequences of mining with rock backfill and rock-cemented backfill show that the high principal stress (Sigma 1) is in the range of 10-153 MPa, and the safety factors are in the range of 0.63-1.89. Therefore, mining sequences with cemented backfill and under cemented backfill have a principal stress (Sigma 1) in the range of 10-112 MPa and acceptable safety factors. Originality. In this study, the bottom-up mining sequence with a cemented backfill is proposed for the case of low-quality serpentine footwall. This mining sequence aims to achieve good cobalt mine production and provides a safe environment for miners. Practical implications. In the mining industry, the choice of mining method using 2D or 3D geotechnical numerical mo-deling is important to ensure the safest and most operational mining sequence in the mine lifetime.

During earthquakes, the shear strength and bearing capacity of saturated sandy soils decreases; this is related to an increase in pore pressure. In the ultimate state, the pore pressure becomes equal to the initial effective stress, at which time the material loses all its resistance and liquefaction occurs. Thus, the prediction of the post-liquefaction settlement of the soil is an important step to reduce the seismic risk. Several methods have been developed for the prediction of Seismic-Induced Settlement, the most widely used is that based on the results of in-situ tests SPT, and Several soil reinforcement techniques can be considered, the choice depends mainly on the grain size of the soil to be treated. This article presents a comparative study of the methods for evaluating Seismic-Induced Settlement based on the experimental results of the in situ SPT tests, applied to an earthquake-prone area in northern Morocco which had specific soil formations characterized by the existence of layers of sand over several meters, which suggests the possibility of soil liquefaction and proposes a method of reducing the risk of liquefaction. The analysis of existing SPT data leads to interesting conclusions both in terms of the comparative analysis of methods for the prediction of the post-liquefaction settlement and the understanding of the effect of Soil treatments by Stone Columns to mitigate the risk of liquefaction.

Several processes allow the improvement of soils such as vibrocompaction, stony columns, static horizontal compaction etc. These processes reduce the risk of liquefaction potential and making it possible to build on this type of soil when the space restriction require it. Stone columns are a recognized method of soil improvement, which consists of creating large diameter columns using special vibrators with granular filling materials introduced into the ground. The objective of this work is to evaluate the effectiveness of stone columns, made in a seismic zone containing liquefiable materials, with regards to the reduction of the risk of liquefaction and the improvement of the bearing capacity of the soil. The approach followed is the exploitation of geotechnical investigation tests (CPT Cone Penetration Test), (SPT: Cone Penetration Test, (pressuremeter tests), carried out before and after soil treatment. This study showed that the network of gravelled columns produces an enhanced soil improvement effect by improving the modulus of elasticity of the soil and reducing settlement and the risk of liquefaction after treatment. The process allows for the improvement of the geotechnical characteristics of its soils, making it possible to build infrastructure and development projects in the area.