Résumé : Le Rif Marocain en général et la ville d’Al Hoceima et sa périphérie urbaine plus particulièrement, connaissent fréquemment des aléas géomorphologiques, notamment les glissements de terrain qui entravent la gestion urbaine. Ce type d’aléa naturel est de grande actualité, aussi bien sur le plan scientifique que sur le plan médiatique, à cause de l’augmentation de la vulnérabilité, due aux circonstances des changements globaux (réchauffements climatiques) et à la forte urbanisation, souvent irrationnelle. L’objectif de cet article est la mise en place d’une approche objective visant l’évaluation de la susceptibilité aux glissements de terrain dans la ville d’Al Hoceima et sa périphérie. La théorie de l’évidence, qui est une méthode probabiliste bivariée, est fondée sur les règles de Bayes qui consistent à calculer la probabilité d’occurrence spatiale de glissements de terrain, en se basant sur la notion de probabilité à priori et de probabilité à posteriori, tout en considérant les glissements de terrain comme variable à modéliser et chaque facteur causatif comme variable prédictive. Le but de ce travail est de procéder à un zonage d’aléa glissement de terrain tout en assurant une bonne prédiction de ce phénomène avec une bonne résolution spatiale. Les résultats de la courbe de ROC (Receiver Operating Characteristic) montre que la confrontation de la carte de susceptibilité, des glissements de terrain à la carte d’inventaire, permet une capacité de prédiction considérable (AUC=0,889). Ceci pousse au constat selon lequel, plus de 2/3 des glissements de terrain inventoriés s’inscrivent dans des classes de susceptibilité élevée et très élevée. Ce produit cartographique peut constituer un puissant outil d’aide permettant la formulation des suggestions, dans le but d’optimiser l’évaluation du risque de glissements de terrain dans les zones exposées à ce phénomène. Mots clés : SIG, Théorie de l’évidence, Susceptibilité aux glissements de terrain, Al Hoceima (Maroc)

The scarcity of water resources presents the most threatening risk and its effects are beginning to affect several regions of the planet. It cannot be denied that Morocco, due to its location in the south of the Mediterranean, has been affected by these climatic trends of which the plateau de Sais offers a good example by its location in the center of the country and by its wealth of superficial and groundwater resources. In recent decades, this plateau has experienced water stress, particularly in its groundwater reserves. It has been manifested by the decrease in flows from several springs or even total drying up in particular after successive periods of unusual drought, which marked the whole of the country after the 1980s. It is in this perspective this study aims to understand the behavior of the hydrogeological functioning of the springs located in the plain of Fez and its middle Atlas borders. Its geological complexity, as well as the abundance of carbonate rocks and the presence of volcanic basalt flowing from South to North have favored the resurgence of several springs of different flows and with a hydrological regime influenced according to the years and seasons by rainfall inputs. All these physical factors as well as human intervention on the hydrosystem through hydro-agricultural activities influence the behavior of the hydrological functioning of these springs.

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Morocco in general and the Mediterranean watersheds of the Western Rif in particular, occasionally have been affected by the negative impacts of drought, as demonstrated by the drought

The lack of a complete and reliable data series often represents the main difficulty in carrying out climate studies. Diverse causes, such as human and instrumental errors, false and incomplete records, and the use of obsolete equipment in some meteorological stations, give rise to inhomogeneities that do not represent climatic reality. This work in the northern part of the Moroccan Middle Atlas used 22 meteorological stations with sometimes-incomplete monthly precipitation data from 1970 to 2019. The homogenization and estimation of the missing data were carried out with the R software package Climatol version 3.1.1. The trends in the series were quantified by the Mann–Kendall nonparametric test. The results obtained show a low root mean square error (RMSE), between the original and homogenized data, of between 0.5 and 38.7 mm per month, with an average of 8.5 mm. Rainfall trends for the months of December through June are generally downward. These negative trends are significantly stronger in the southern and eastern parts of the study area, especially during the month of April (the wettest month). On the other hand, July shows positive trends, with 71% of stations having an increasing precipitation tendency, although only five (or 1/3) of these are statistically significant. From August to November, generally positive trends were also observed. For these months, the percentage of series with a positive and significant trend varied between 55 and 77%.