Water stress is one of the factors controlling agricultural land salinization and is also a major problem worldwide. According to FAO and the most recent estimates, it already affects more than 400 million hectares. The Tafilalet plain in Southeastern Morocco suffers from soil salinization. In this regard, the GIS tools and remote sensing were used in the processing of 19 satellite images acquired from Landsat 4–5, (Landsat 7), (Landsat 8), and (Sentinel 2) sensors. The most used indices in the literature were (16 indices) tested and correlated with the results obtained from 25 samples taken from the first soil horizon at a constant depth of 0.20 m from the 2018 campaign. The linear model, at first, allows the selection of five better indices of the soil salinity discrimination (SI-Khan, VSSI, BI, S3, and SI-Dehni). These last indices were the subject of the application of a logarithmic model and polynomial models of degree two and four to increase the prediction of saline soil.. After studies and analysis, we concluded that the second-degree polynomial model of the salinity index (SI-KHAN) is the most efficient one for detecting and mapping soil salinity in the Tafilalet oasis, with a coefficient of determination (R²) and the Nash–Sutcliffe efficiency (NSE) equal to 0.93 and 0.86, respectively. Percent bias (PBIAS) calculated for this model equal was 1.868% < 10%, and the low value of the root mean square error (RMSE) confirms its very good performance. The drought cyclicity led to the intensification of the soil salinization process and accelerated soil degradation. The standardized precipitation anomaly index (SPAI) is strongly correlated to soil salinity. The hydroclimate condition is the factor that further controls this phenomenon. An increase in salinized surfaces is observed during the periods of 1984–1996 and 2000–2005, which cover a surface of 11.50 and 24.20 km², respectively, while a decrease of about 50% is observed during the periods of 1996–2000 and 2005–2018.

The use of vegetation is one of the effective methods to combat the increasing Urban Heat Island (UHI). However, vegetation is steadily decreasing due to urban pressure and increased water stress. This study used air temperature measurements, humidity and an innovative advanced earth system analysis to investigate, at daytime, the relationship between green surfaces, built-up areas and the surface urban heat island (SUHI) in Marrakesh, Morocco, which is one of the busiest cities in Africa and serves as a major economic centre and tourist destination. While it is accepted that UHI variation is generally mitigated by the spatial distribution of green spaces and built-up areas, this study shows that bare areas also play a key role in this relationship. The results show a maximum mean land surface temperature difference of 3.98 °C across the different city neighbourhoods, and bare ground had the highest correlation with temperature (r = 0.86). The correlation between the vegetation index and SUHI is decreasing over time, mainly because of the significant changes in the region’s urban planning policy and urban growth. The study represents a relevant overview of the factors impacting SUHI, and it brings a new perspective to what is known so far in the literature, especially in arid climate areas, which have the specificity of large bare areas playing a major role in SUHI mitigation. This research highlights this complex relationship for future sustainable development, especially with the challenges of global warming becoming increasingly critical.

Cette étude a été conduite dans l’extrême sud-ouest du Niger, à l’échelle du bassin versant du Kori Ouallam. Elle se propose d’évaluer les pertes potentielles en sols induites par l’érosion hydrique en lien avec les contraintes naturelles et l’anthropisation. La méthodologie adoptée implique des campagnes de terrain, des analyses au laboratoire confrontées aux outils composés du Système d’Information Géographique (SIG), de la Télédétection et de l’Equation Universelle des pertes en Sols Révisée (RUSLE). L’exploitation de ces données révèle que la moyenne annuelle des pertes potentielles en sols générée par l’érosion hydrique est de 1,54 t/ha/an. A l’échelle du bassin versant, le risque érosif varie d’un taux d’érosion très faible (0-0,5 t/ha/an) largement observé au nord à un taux d’érosion extrêmement sévère (> 5 t/ha/an) avec un gradient croissant vers le sud. La matrice de corrélation montre que les facteurs topographiques liés à la longueur (L) et l’inclinaison de la pente (S) constituent les principaux facteurs érosifs influençant les pertes en sols. L’érodibilité des sols et l’érosivité des pluies interviennent de façon secondaire. La dégradation progressive des sols par l’érosion hydrique est également amplifiée par des activités humaines inappropriées ce qui fragilise la résilience des écosystèmes et celle des communautés. Dans un contexte sahélien marqué par des incertitudes climatiques et une forte anthropisation, le schéma régional de la dynamique érosive des sols mérite davantage une surveillance adéquate pour une gestion durable des ressources naturelles.