Spatial distribution and genesis of salt on the saline playa at Qehan Lake, Inner Mongolia, China

Abstract

Inland salt lakes and saline wetlands are intricate systems in which moisture and salinity are continuously changing and especially sensitive to climate change and human pressure. Remote sensing helps to monitor the dynamic changes in the moisture and salinity of salt lakes and saline wetlands. Based on the Landsat 8 satellite data, this paper developed a multivariable linear regression model (MLRM) to predict the spatial distribution of salt on the saline playa at the Qehan Lake in Inner Mongolia, China. The developed MLRM used the remote sensing spectral indices and the Tasseled Cap Transformation wetness band (TCTW) as a variable. By using the TCTW and the surface temperature inversion data, the response of salt to surface moisture and temperature in the dry lake bed was explored. The results showed: The MLRM with brightness index (BI) and the TCTW as the auxiliary variables has the nice applicability (Radj2 = 0.598, RMSE = 1.640). The MLRM established using the vegetation index NDVI may be more applicable to environments where vegetation and salts were doped-together. Salt distribution in the Qehan Lake may be controlled by flat lake bed and miniature piedmonts. There was a significant correlation between measured soil electrical conductivity (EC) and TCTW, but no correlation with surface temperature. The influence of surface temperature on salt may be biased towards the time scale.