EVALUATION OF INDICATOR KRIGING APPROACHES TO MAP THE SOIL PARENT MATERIAL IN MOUNTAINOUS AREAS OF SOUTHERN BRAZIL

Indicator kriging is one of the main tools available for estimating the uncertainty associated with categorical variables used as ancillary information to build predictive models of soil properties. But there are several variants of the kriging interpolator. Ordinary kriging and cokriging are two of them. There are also several parameters that can be set to define how the kriging interpolator will predict the probability of occurrence of a given indicator variable in a certain location. Local and global (co)kriging are two of them. Every time a different variant of the kriging interpolator is used, and every time a parameter is set in a different way, different predictions are yielded. The uncertainty associated with this feature is defined as the uncertainty about model specification. The present study produced results that can help to understand this source of uncertainty, and perhaps help to reduce it. More specifically, the results can help choosing the kriging interpolator and setting its parameters accordingly.