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Sedimentary Facies and Depositional Environment of Oligo-Miocene of the Southern Shore of the Strait of Gibraltar (Rif, Morocco)

Salhi Fouad, El Khalidi Khalid, Zourarah Bendahhou

Ecological Engineering & Environmental Technology

2024

Vol. 25, iss. 3

233--252

This paper highlights a detailed sedimentological investigation of the deposits of Oligo-Miocene age on the southern shore of the Strait of Gibraltar commonly called flyschs Numidian, micaceous-sandstone flysch of Beni Ider and merinid flysch. This study has allowed us to demonstrate the existence of different facies and environments linked to the different processes that prevail in the Maghrebian basin under the simultaneous control of sedimentary input, eustatism and the tectonic process. Our study is based on the observation and the detailed stratonomic analysis of the different facies encountered in the Oligo-Miocene age series of flyschs from the southern shore of the Strait of Gibraltar. For the first time, this analysis shows that the Numidian successions studied, except that of Oued Lihoud, were deposited in deltaic environments (deltaic cone) at the level of the North African margin (Rif chain). These are prodelta deposits where slides, slumps or turbidites of predominantly fluvial delta fronts, regular waves and storm waves, fluvial and estuarine channels and tidal plains are sometimes intercalated. The micaceoussandstone flyschs are due to gravitational sedimentation at the level of the submarine plain of the Maghreb basin. We have identified different categories of deposits: low, medium and high density turbidites, pulsation turbidites, homogenites, debris-flows and contourites. The Merinid flyschs are also due to mixed gravity sedimentation from a lithological point of view between the Numidian sandstones and the micaceous-sandstoneof Beni Ider. These deposits have therefore occupied an intermediate position between the southern and northern margins of the Maghrebian basin. In addition to the gravity facies, the deposits show high-density megaturbidites. This study also allowed the identification a major eustatic decline that was recorded during the Oligocene, the cold climate of the Oligocene and distensive (north) and compressive (south) tectonic movements depending on the position in the basin.

Landslide Hazard Assessment in the Heterogeneous Geomorphological and Environmental Context of the Rif Region, Morocco – A Machine Learning Approach

Hamidi Maryem, Bouramtane Tarik, Abraham Shiny, Kacimi Ilias, Barbiero Laurent, Kassou Nadia, Valles Vincent, Levy Gad

Ecological Engineering & Environmental Technology

2023

Vol. 24, iss. 8

272--292

Landslides are considered to be one of the most significant and critical natural hazards in the heterogeneous geomor-phological setting of the Rif region of Morocco. Despite the high susceptibility to landslides, the region lacks detailed studies. Therefore, this research introduces four advanced machine learning methods, namely Support Vector Machine (SVM), Classification and Regression Trees (CART), Multivariate Discriminant Analysis (MDA), and Logistic Regression (LR), to perform landslide susceptibility mapping, as well as study of the connection between landslide occurrence and the complex regional geo-environmental context of Taounate province. Fifteen causative factors were extracted, and 255 landslide events were identified through fieldwork and satellite imagery analysis. All models performed very well (AUC > 0.954), while the CART model performed the best (AUC= 0.971). However, SVM demonstrated superior performance compared to other methods, achieving the highest accuracy (89.92%) and F1-measure (81.66%) scores on the training data, and the highest accuracy (83.01%), precision (81.74%), and specificity (79.46%) scores on the test data. The results do not necessarily indicate that LR and MDA have the lowest predictive ability, as they demonstrated high accuracy in terms of AUC and in some classification tasks. Moreover, they provide the significant advantage of easy interpretation of the geo-environmental processes that control landslides. Rainfall is the primary triggering factor of landslides in the study area. The majority of landslides occurred on slopes, particularly those located along rivers and faults, suggesting that landslides in the region are closely associated with active tectonics and precipitation. All four models predicted similar spatial distribution patterns in landslide susceptibility. The results showed that almost half of the area mainly in the north and northwest, has a very high susceptibility to landslides. The findings provide valuable references for land use management and the implementation of effective measures for landslide prevention.

An Estimation of Soil Erosion Rate Hot Spots by Integrated USLE and GIS Methods: a Case Study of the Ghiss Dam and Basin in Northeastern Morocco

Taher Morad, Mourabit Touafik, Bourjila Abdelhak, Saadi Omar, Errahmouni Ali, El Marzkioui Fouad, El Mousaoui Mhamed

Geomatics and Environmental Engineering

2022

Vol. 16, no. 2

95--110

Soil erosion is a major factor leading to dams’ siltation and reducing their storage capacity. This study mapped the hot spots of soil erosion areas to predict the soil erosion/siltation in the Ghiss basin/dam (northeastern Morocco). In this context, various data has been prepared in the geographical information system for the estimation of soil erosion by integrating the universal soil loss equation (USLE). The result of this study revealed that soil loss rate ranges between 0 and 19 t∙ha−1∙yr−1. Therefore, the hot spots in the soil erosion area are to be found upstream, potentially leading to dam siltation over time. To avoid Ghiss dam siltation, we suggest terrace farming and reforestation in the soil erosion area hot spots.