In analysing the spectral response of saline soils using atmospherically corrected LANDSAT 8 OLI data, I am finding most salinity indices saturate after 8 or 9dm. Any similar experience or I have a mistake somewhere?? Thanks
I had experience in estimating soil salinity using regression models. In general, highly saline soils were not well fitted by most models. One explanation may be the unique spectral features of these soils, such as the existence of hygroscopic salt (soil moisture interference) and salt crust (always highly reflective). The phenomenon is similar to the saturation of NDVI.
Yes, it is normal because soil salinity indices are only simple indicators for probable salt-affected soil but not for correct quantification. You must use a physical or semi-empirical model (calibration with EC measured at the laboratory) for accurate predection even for pure Sabkha with 500 dS/m.