Soil moisture estimation using c-band synthetic aperture radar data
2016
Calanoga, D.F.
Synthetic Apenture Radar (SAR) is widely used for land and ocean monitoring because of its capability to acquire images dry and night regardless of the presence of clouds and precipitation. For this study, SAR data were used to estimate soil moisture content at depths of 0-5 cm and at 5-10 cm on bare and sparely vegetated surfaces in and near the University of the Philippines Los Baños. Two methods were used for soil moisture estimation. The first method involved development of an empirical relationship between values from different backscatter configuration and soil moisture. The second method, on the other hand, was adapted from Advanced Synthethic Aperture Radar Global Monitoring mode change detection method. This approach assumes that the average characteristics of a surface do not change significantly over radar passes attributing only backscatter changes to soil moisture changes. Use of VV backscatter values for both the first and second methods resulted to a good agreement with in situ soil moisture at 0-5 cm depth. Validation showed that use of VV backscatter values in the second method led to better estimates with R sup 2, MAE, RMSE, and IoA values of 82%, 0.07%, 4.222% and 0.94, respectively. The use of this method was then proposed bearing in mind that the range of backscatter and soil moisture in the model development will serve as the upper and lower bounds of the validity of the approach.
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