DERIVATION OF SOIL PROPERTIES USING A SOIL LAND INFERENCE MODEL (SOLIM)

SoLIM (Soil Land Inference Model) is a fuzzy inference scheme for esti mating and representing the spatial distribution of soil types in a la ndscape. This study developed the inference method a step further to d erive continuous soil property maps through two case studies. The firs t case illustrates the derivation of soil A horizon depth in a mountai nous area in western Montana. It was found that the inferred depths ar e a closer fit to observed depths than those derived from the conventi onal soil map at both spatial and attribute levels. The second case sh ows the derivation of soil transmissivity values across a small catchm ent with a gentle environmental variation in Tumut, NSW, Australia. Th is case shows that the derived soil transmissivity map is comparable t o the results from systematic held survey over a small area. SoLIM wor ks well in an area where there is a good understanding of the relation ships between soils and their formative environment and where the soil formative environment can be characterised using current geographical information system techniques. However, we experienced difficulty wit h the methodology when it was applied in an area where the environment al gradient is gentle and the soil formative environment cannot be ver y well described using the primitive environmental indices currently e mployed in SoLIM.