Mapping of Soil Salinity Using the Landsat 8 Image and Direct Field Measurements: A Case Study of the Tadla Plain, Morocco

Soil salinization from arid to semiarid climate is a serious environmental problem. In some countries, salinization is considered a real threat to food security and food quality because it lowers crop yields and can irretrievably damage land. In the irrigated area of the plain of Tadla (Central Morocco), the intensive use of groundwater and saline surfaces lead to the degradation of soil quality. Experimental methods of monitoring soil salinity by direct real-time measurements are in high demand, but also very limited in terms of spatial coverage. The objective of this paper is to map soil salinity in the arid and semiarid zone of the Tadla plain in Morocco, based on optical remote sensing data and field measurements of sodium absorption ratio. The first results of work were devoted to the evaluation and validation of salinity models in the study area. Observations on the site, correlation, verification and validation of the model enabled us to map the salinity. All these use the soil salinity map based on non-saline soil content, light saline soil, moderate saline soil and highly saline soil. The map obtained from our model allowed us to identify the distribution of salinity in the study area. The values of the electrical conductivity in the study area range from less than 2 ds/m (non-saline soil) to more than 8 ds/m (highly saline soil) with a significant variation between the different levels of soil salinity in the study area.