Significance and application of the multi-hierarchical landsystem in soil mapping

A methodological framework to formalise the landscape knowledge of the soil surveyor is presented. It requires structuring of terrain objects in a nes ted hierarchy, followed by inference and formalisation of knowledge rules. We demonstrate how these rules can be applied in a GIS environment for lear ning and communicating knowledge. Object subdivision is based on the techni que of hierarchical subdivision derived from surveyor experience. Formalisa tion of contextual knowledge requires (1) description of the semantics of o bject levels in relation to scale, (2) definition of objects and attributes and their relation to higher and lower level objects, and (3) the knowledg e inferred from the objects and its inclusion in the database. The Alora ca se study (South Spain) illustrates the value of the different object levels of the hierarchy for obtaining information on both soils and land evaluati on. Often more than one context (object hierarchy) has to be considered to predict this information. We argue that a GIS database requires proper desc ription of the different kinds of formal relationships that exist between o bjects and object classes, and between elementary and composite objects. We also show that the different scale levels of the multiple hierarchy play a n essential role in conveying knowledge for an interdisciplinary applicatio n (land evaluation, land use, erosion, and hydrology). (C) 2001 Elsevier Sc ience B.V. All rights reserved.