In addition to discharge observations, remotely sensed soil moisture estimates improve the calibration of large-scale hydrological models as shown by Niko Wanders in a recent publication in Water Resources Research. In this paper a dual state-parameter Ensemble Kalman Filter is used to calibrate the hydrological model LISFLOOD for the Upper Danube. Calibration is done using discharge and remotely sensed soil moisture acquired by AMSR-E, SMOS, and ASCAT.
Wanders, N., M.F.P. Bierkens, S.M. Jong, A. Roo, and D. Karssenberg, 2014. The benefits of using remotely sensed soil moisture in parameter identification of large-scale hydrological models. Water Resources Research 50 (in press).