Modeling of soil salinity in Rheris Oasis (Southeastern of Morocco) using satellite spectral indices

¹ Geo-resource Geo-environment Geological and Oasis Heritage Research Team, Faculty of Sciences and Techniques of Errachidia, Moulay Ismail University, Errachidia, Morocco.
² Center of Applied Research, Karlsruhe University of Applied Sciences, 76133 Karlsruhe, Germany.
³ Crop Science, Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-University of Berlin, Berlin, Germany.
⁴ National Institute for Scientific and Technological Research in Water, City of Innovation Souss Massa, Ibn Zohr University, Agadir, 80000, Morocco.
⁵ Applied Geology and Geo-Environment Laboratory, Faculty of Sciences, Ibn Zohr University, Agadir, 80035, Morocco.
⁶ Geology and Sustainable Mining Institute (GSMI), Mohammed VI Polytechnic University, Lot 660, Hay Moulay Rachid, 43150 Benguerir, Morocco

^* Corresponding author: i.aitlahssaine@edu.umi.ac.ma

Abstract

The Rheris oases in Southeastern Morocco are an essential ecosystem. It presents enormous ecological and natural values. Water scarcity coupled with agricultural intensification results in soil salinization and its degradation. This work aims to propose a spatiotemporal monitoring method of soil salinization in the Rheris oasis using spectral indices derived from Thematic Mapper (TM) and Operational Land Imager (OLI) data. The most used indices in the literature were (14 indices) tested and correlated with the results obtained from 50 samples taken from the first soil horizon at a constant depth of 0.20 m from the November 2022 campaign. The findings confirm that this method is highly effective and reliable for the modeling and spatial mapping of soil salinity in this region. The state of the hydroclimate is an aspect that influences soil salinization. An increase in salinized surfaces is observed during the periods of 1990–1996, 2000–2005, and 2017-2022. The spatio-temporal distribution of saline soils in Rheris Oasis is very variable. The monthly variations are more important than the annual ones.