USE OF REAL-TIME REMOTE SENSING DATA FOR EVALUATING SOIL MOISTURE AND SALINITY EFFECTS ON LIGHT PENETRATION DEPTH

摘要

Active and passive microwave remote sensing systems have been widely used for determination of soil moisture and salinity due to the high penetration depth and sensitivity of microwaves. We used optical remote sensing data and investigated the effects of soil moisture and salinity on the penetration depth of light into the soil using real-time ground spectral measurements around Salt Lake, Turkey. Reflectance spectra were simultaneously measured using field spectroradiometer at different depths starting from the soil surface during the overpass of Landsat-5 over the study area. The correlation between the reflectance spectra of each layer and spectral radiance obtained from TM data was examined. The results indicate a good correlation between observed and predicted reflectance spectra for each layer and are consistent with results obtained from the same instrument in previous experiments. One of the most important result of the study is that soil moisture formed under salt crust into the crusted saline soil (CSS) negatively affects the light penetration depth in the shortwave infrared region of the electromagnetic spectrum. Experimental results obtained in the study show that light penetration depth into the CSS is just 0-0,5cm, while it is between 0 and 2,5cm into the bare saline soil (BSS). The results also show that spectral bands having relatively long wavelength such as TM5, TM7 are more correlated with the lower layers.