Soil Moisture Monitoring with Dual-Incidence-Angle RISAT-1 Data: A Pilot Study from Vidarbha Region

Abstract

Soil moisture is a crucial parameter in the estimation of crop yield, drought forecast, hydrological and climatic studies. Soil moisture retrieval from synthetic aperture radar data is yet to be operational due to difficulty in removing the influence of vegetation and roughness in the backscattering signal. This limitation is addressed in this study by a combination of lower and higher incidence angle RISAT-1 SAR data. Roughness was derived using a linear model prepared by correlating σ°high HH–σ°low HH with root mean square height of the ground roughness component. A new attempt is made to remove the influence of vegetation using a model prepared by integrating the radar vegetation index and normalized differential vegetation index. The derived soil moisture was validated with the ground-truth data with the R2 value of 0.62 and with the error of 5.4% (volumetrically).