Estimating soil hydraulic properties from time series of L-band measured water contents

In this paper, we present an approach to estimate the hydraulic properties based on time-series of water content measurements in the topsoil at the plot scale. The data base consists of series of ground-based remotely sensed water contents by using a 1.4 GHz (L-band) and 11.4 GHz radiometer as well as in-situ TDR measurements. A technical description of the new L-band radiometer will also be presented at this meeting (Schneeberger et al., 2003). The measuring period contained several natural rainfall and dry-down cycles. In order to test the possibility to derive soil structural information from this approach, we depend on a high temporal resolution of the measurements. The comparison of the in-situ and remotely sensed water contents by the microwave radiometers revealed a synchronous behavior. Although preferential flow was neglected in the modeling approach, we were able to get a satisfying fit to the in-situ measured water contents. The comparison of the derived parameters to literature data revealed a structural influence, since the parameter combination lies outside the confidence interval. This indicates that the behavior of structured soils may be extractable from remotely sensed topsoil water dynamics.