Topographic Influences on Seasonal Drought in Morocco’s Western Rif: Insights from a 40-Year SPI-3 Analysis

Understanding the spatial variability of drought in mountainous coastal environments is crucial for anticipating hydrological stress and improving drought preparedness. This study examines the influence of static topographic factors, including elevation, slope, and proximity to the coastline, on seasonal drought patterns in the Western Rif region of Morocco over 40 years (1980–2019). Multiple linear regression models for autumn, winter, and spring were implemented using the Standardized Precipitation Index (SPI) computed on a seasonal scale (SPI-III) from 17 meteorological stations. Topographic data were extracted from a 30 m Shuttle Radar Topography Mission (SRTM) digital elevation model using GIS-based processing tools. Regression diagnostics, including variance inflation factor (VIF), Shapiro–Wilk test, and Breusch–Pagan test, confirmed the statistical validity of the models. The results reveal that distance to coast is the most influential variable, with statistically significant effects during winter (p = 0.003), reflecting the inland attenuation of maritime air masses and orographic enhancement. In contrast, models for autumn and spring displayed weak predictive capacity, suggesting the dominance of convective or stochastic mechanisms during transitional seasons. Elevation exhibited limited explanatory power, while slope was consistently non-significant. This study emphasizes the conditional nature of topographic control on drought and highlights the importance of seasonally adaptive frameworks for spatial drought modeling. The integration of physiographic metrics within early warning systems could enhance climate resilience strategies in Mediterranean mountain regions. Future research should incorporate dynamic climatic indices and non-linear modeling approaches better to capture the complexity of rainfall–topography interactions.