Fuzzy logic and differences between interpretive soil maps

Interpretive soil pre-mapping is essentially a geovisualization enterprise. It involves the creation of soil-landscape mental models that underpin soil boundary delineation. For a given area, different soil scientists will inevitably produce different interpretive soil maps regardless of whether they use similar or different tools and techniques. Only one official soil map normally created by an individual soil scientist is provided by national soil mapping agencies. The extent and gravity of the differences between this map and other possible soil map perspectives of the area is largely unknown. This paper draws upon a fuzzy logic approach to quantify the magnitude and seriousness of the differences between two interpretive soil maps. One map was created by an individual soil scientist using traditional soil mapping methods. The other was produced by four collaborating soil scientists concurrently immersed in an innovative Experiential GIS environment. The fuzzy method dovetails nicely with the imprecise and predominantly qualitative nature of interpretive soil mapping. It determined the degree of overall disagreement between the interpretive maps and specifically between a soil pre-map and a final soil map as at least 43%. The method illuminated the difficulty in differentiating different soil classes and the gravity of consequent soil misclassifications through the feedback from independent soil data quality specialists. This feedback was also displayed in intuitive surface map form. Rather than encourage the creation of several same area and same scale soil maps by several independent soil scientists, this study advocates collaborative soil mapping to embed multiple perspectives into the official soil map. The joint effort does not, however, necessarily lead to a more detailed soil map as the collaborating soil scientists may be lumpers instead of splitters.