Geospatial and Temporal Assessment of Soil Salinization and Drought Using the Spi Index in an Irrigated Area in a Semi-Arid Zone: The Case of Beni-Amir (Central Morocco)

Abstract

Soil salinization is one of the main factors contributing to the degradation of agricultural land in arid and semi-arid regions. It permanently compromises the productivity and sustainability of irrigated systems in these areas. In the irrigated area of Beni Amir in central Morocco, recurring droughts exacerbate this phenomenon. This study aims to evaluate the spatial and temporal evolution of soil salinity from 2013 to 2023, characterize drought trends using the Standardized Precipitation Index (SPI) from 1990 to 2023, and explore the relationship between climate variability and salinization. The results show a notable increase in electrical conductivity, particularly in the deep profile (20–40 cm). The most vulnerable areas are located in the southern and eastern parts of the perimeter. Analysis of the SPI reveals a succession of moderate to severe droughts over the last three decades, peaking in 2019 and 2022. A statistical comparison of the two variables highlights a negative relationship between the SPI and salinity. This suggests that water deficits directly contribute to salt accumulation. These results confirm the role of droughts in exacerbating salinization and highlight the importance of incorporating climate variability into sustainable irrigation and soil conservation management strategies.