Spatio-temporal dynamics of soil moisture in an agricultural watershed
McVey, Ross Alexander
PublisherUniversity of Hull
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The spatial and temporal dynamics of surface, 0-0.06m, soil moisture over a 24Ha agricultural site is examined by using spatially intensive empirical point measurements. Statistical analyses of the soil moisture indicate a variable spatial structure with antecedent rainfall and time of the year having the greatest influence on the spatial field. Static and dynamic indices do not have consistent statistically significant relationships with the soil moisture fields. The spatial correlation structure has a temporal evolution, in terms of the amount of spatial variance and the organisation of the spatial soil moisture field, which is dependent on the mean moisture content. Several interpolation procedures are considered to analyse the linkage between measurement and modelling scale. Ordinary kriging provides the best goodness of fit between the computed realisation and the empirical data, but simplifies the data and a value for the uncertainty value is not calculable. Conditional simulation allows for the assessment of the uncertainty, but with a reduced accuracy between the representation and the empirical data. Comparison of the surface moisture and hydrological flux within the profile shows that the soil moisture at this depth is disassociated from the hydrological processes at depth. One-dimensional modelling of the moisture fluxes returns a close association between the modelled and measured moisture, even with inaccurate modelling of the fluxes. Thus, limiting the applicability of shallow surface soil moisture in the internal validation of current generations of hydrological models.