Information content of time domain reflectometry waveforms

The possibility to link model parameters with soil properties is obstructed if identification problems in inverse modeling of time domain reflectometr y (TDR) waveforms occur. Therefore multiple objective functions, each assoc iated with one model parameter, are sought for identification of probe (res istance and length) and Debye (static permittivity, high-frequency permitti vity, relaxation frequency, and bulk electrical conductivity) parameters in TDR waveforms. An objective function could be defined for all six model pa rameters. Some of the defined objective functions correspond with theoretic al and experimental observations of earlier work. Other new insights have b een obtained. For instance, it is possible to obtain estimates of high-freq uency permittivity even when the reflection of the end of the probe has van ished because of high salinity. Application of the found objective function s on measured TDR waveforms yielded parameter values that compared well wit h values obtained from several references. However, identification of a par ameter is only possible if its true value lies within the frequency bandwid th of TDR.