Three‐dimensional geological maps that include the hydrostratigraphical heterogeneity and depositional architecture of the natural formation are needed in hydrogeology to understand flow and transport. This paper presents a practical procedure for the generation of such maps. The method includes multiple indicator kriging, where the estimation of the structural architecture is conditioned on ground penetrating radar data. Physical core samples are used as tie points. This study utilizes data obtained from the unsaturated zone of a highly heterogeneous, glaciofluvial delta formation in Norway.

A model is put forward which focuses on the dynamical evolution of the spatial distribution of snow water equivalent (SWE). We make use of the fact that when the accumulation and ablation process of the snow reservoir is modelled as a summation of a gamma-distributed variable, both skewed distributions, typical of alpine areas, and more normal distributions, typical of forested areas, can be accounted for. A particular problem is to represent fractional snow-covered area (SCA) within the distribution framework. The change in SCA as a response to a melting event is explicitly linked to the shape of the distribution of SWE and is estimated as the probability of non-exceedance of the melted amount from a scaled version of the spatial distribution of SWE. An extensive snow-measuring programme, where several snow courses have been measured repeatedly throughout the melting season, justifies the dynamical aspects of the snow distribution in the modelling approach. The modelling approach has been tested with the Swedish rainfall–runoff model, HBV, and estimated values of SWE and SCA are compared with results obtained using the statistical distribution (log-normal) traditionally used in the model.

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The water balance of a 600 mz field site on a lateritic hillslope in Kerala, southwest India, has been studied during two southwest monsoon seasons. Surface runoff was of minor importance while infiltration and evapotranspiration were the major components amounting to approximately 2/3 and 1/3 of the rainfall, respectively. Groundwater response was rapid, involving fluctuations of several metres. Recharge mechanisms hypothesized are water movement via preferred pathways from the ground surface to the capillary fringe where rapid rise in groundwater level is brought about by a transmitted pressure pulse. Groundwater recharge was found normally to take place during the southwest monsoon season only. The field study demonstrates that seasonal shallow groundwater recharge representing the major portion of the rainfall may be observed in this lateritic terrain in the humid tropics. It indicates a good potential for further groundwater development. Moreover, conditions are conducive to a considerable contribution to possible recharge to deeper aquifers. The observed groundwater recharge is the result of a complex process on which further research will throw more light.

The spatial distribution of soil moisture defines preferential flow paths in the unsaturated zone. Hence, three dimensional (3D) estimates of soil moisture are of great importance to understand transport of contaminants as well as remediation processes in the unsaturated zone. In this study 3D estimates conditioned on spatially frequent observations of soil moisture, have been obtained by kriging. The observations were divided into subdomains consistent with the local stratigraphy and directional semivariogram analysis was applied. It was found difficult to clearly identify a 3D semivariogram function in this case, but from a georadar survey two semivariogram functions were derived, describing two different sedimentological units. By conditioning the estimates of soil moisture on the sedimentological architecture computed by indicator kriging, more accurate estimates were achieved. These improvements were quantified by a ‘jackknife’ cross validation procedure. Besides the practical aspects of finding the most important flow paths estimates of soil moisture are valuable when validating unsaturated flow models.