Kalman filters for assimilating near-surface observations into the Richards equation – Part 3: Retrieving states and parameters from laboratory evaporation experiments

摘要

The purpose of this work is to evaluate the performance of a dual Kalmanfilter procedure in retrieving states and parameters of a one-dimensionalsoil water budget model based on the Richards equation, by assimilatingnear-surface soil water content values during evaporation experiments carried outunder laboratory conditions. The experimental data set consists ofsimultaneously measured evaporation rates, soil water content and matricpotential profiles. The parameters identified by assimilating the datameasured at 1 and 2 cm soil depths are in very good agreement with thoseobtained by exploiting the observations carried out in the entire soilprofiles. A reasonably good correspondence has been found between theparameter values obtained from the proposed assimilation technique and thoseidentified by applying a non-sequential parameter estimation method. Thedual Kalman filter also performs well in retrieving the water state in theporous system. Bias and accuracy of the predicted state profiles areaffected by observation depth changes, particularly for the experimentsinvolving low state vertical gradients. The assimilation procedure provedflexible and very stable in both experimental cases, independently from theselected initial conditions and the involved uncertainty.