Errors in soil moisture content estimates induced by uncertainties in the effective soil dielectric constant

Soil moisture content (SMC) is an important variable in the hydrological cycle. Sensors have been developed to enable continuous monitoring of SMC (remote sensing from satellite and devices for in situ measurements), many of which are based on measurement of the soil dielectric properties from which SMC is inferred. Most SMC estimation techniques depend on the relationship between SMC and its dielectric properties, but the lack of a universal effective soil dielectric model introduces an additional source of error on SMC estimates. This work compares nine models of this relationship, and quantifies errors due to uncertainties in the relation between water content and dielectric properties. Errors of around 4% are reported with maximum figures at relatively low water content. Inconsistency between these models and the inconsistency in the effect of soil texture on SMC retrieval from satellite-based sensors is also evaluated.