Multifrequency SAR data for estimating hydrological parameters

The sensitivity of backscattering coefficients to some geophysical paramete rs which play a significant role in hydrological processes (vegetation biom ass, soil moisture and surface roughness) is discussed. Experimental result s show that P-band makes it possible the monitoring of forest biomass, L-ba nd appears to be good for wide-leaf crops, and C- and X-bands for small-lea f crops. Moreover, L-band backscattering makes the highest contribution in estimating soil moisture and surface roughness. The sensitivity to spatial distribution of soil moisture and surface roughness is rather low, since bo th quantities affect the radar signal. How ever, observing data collected a t different dates and averaged over several fields, the correlation to soil moisture is significant, since the effects of spatial roughness variations are smoothed. The retrieval of both soil moisture and surface roughness ha s been performed by means of a semiempirical model.