SI - Salinity Index

The salinity index visualizes the amount of salt present in soils. Soil salinization is one of the most common land degradation processes, especially in arid and semi-arid regions, where precipitation exceeds evaporation.

In his study (Elhag, 2016) analysed different  methods employing remote sensing to measure soil salinity, developed through several academic studies. Thematic Mapper (TM), Enhanced Thematic Mapper (ETM+), and Operational Land Imager (OLI-8) pictures from Landsat were the most commonly utilized remote sensing data for mapping soil salinity. Due to the diversity of the research area and/or sensors, several algorithms for determining and mapping soil salinity were created. There have been numerous attempts to find salt-affected soil using remote sensing data and associated methods. Based on the unique reactions of salty soils to different spectral bands, soil salinity indices are primarily tuned to detect salt mineral in soils. By utilizing several soil salinity equations, it is possible to obtain sufficient estimates of soil salinity on a broad scale using remote sensing data.

The purpose of these indicators is to identify salinised soils and distinguish them from non-salinised soils in order to make nature-based solutions more effective when applied

Higher values indicate higher salinity and low values indicate lower salinity.

Generic Formula

Formula by Sentinel-2 bands 

References:

• Elhag, M. (2016). Evaluation of different soil salinity mapping using remote sensing techniques in arid ecosystems, Saudi Arabia. Journal of Sensors, 2016.

• Elhag, Mohamed & Bahrawi, Jarbou. (2017). Soil salinity mapping and hydrological drought indices assessment in arid environments based on remote sensing techniques. Geoscientific Instrumentation, Methods and Data Systems. 6. 149-158. 10.5194/gi-6-149-2017.