Baseline-Based Soil Salinity Index (BSSI): A New Soil Salinity Index for Monitoring Soil Salinization

Soil salinization has degraded a large number of land resources, and is one of the most serious environmental issues occurring on a global scale, particularly in arid and semi-arid regions and coastal areas where evaporation is mainly used to supply precipitation. Monitoring these regions' salinization, due to the numerous distribution of saline and complex form factors, is difficult. The existing spectral index structure only uses the sensitive band for simple calculation, does not consider the impact of the relationship between bands on soil salinization, and can not accurately extract saline soil and characterize the degree of salinization. In this paper, we constructed a new soil salinity index, namely the Baseline-based Soil Salinity Index (BSSI), by introducing the concept of the virtual-baseline. In the configuration of the BSSI, we selected three new bands that are sensitive to saline soil to improve its recognition. BSSI uses the infrared and short-wave infrared-2 bands as the virtual-baseline to measure the height of the short-wave infrared-1 reflectance. Validated by the measured data in the coastal areas of the Yellow River Delta, BSSI is significantly better than other salinity indices, with a correlation coefficient of up to 90%. Meanwhile, the BSSI also was applied to the arid region of Xinjiang, and the results showed that the effect was still the best, which correlation can reach more than 96%. Therefore, BSSI can be used as a reliable indicator of soil salinization monitoring.