Semantics of Parallel Object Hierarchies in a Multi-Scale Environmental Decision-Support System for Watershed Management
Yaser A. Bishr, Marianne R. Molenaar, Maha Radwan · Cartographica The International Journal for Geographic Information and Geovisualization · 1996
Multi-scale representations in GIS traditionally refer to the spatial resolution of geographic objects. That approach stems from the fact that GIS is often used as a mapping tool, with emphasis on the graphical representation of objects. Currently, GIS is not only a mapping tool but also a component that plays an important role in Spatial Decision-Support Systems (SDSSS). Environmental decision making (EDM) in general and watershed management in particular are applications that can benefit from SDSS. These applications may involve agencies of several kinds (e. g., economic, environmental, social) and several levels of decision-making authority (e.g., local, regional, and national). In this context, there is a need for terrain object representations that can he used by various agencies, and at different levels. Inter-agency representations are analogous to the differing semantic descriptions of real-world entitics that appear in various databases, necessitated by different applications. Multi-level representations are analogous to the various levels of abstraction of a real-world entity used within one project. Each agency and/or level of decision making encountered in watershed management may have its own SDSS. A high level of communication between them is required to allow seamless sharing of data and knowledge. In this chapter, we show that services must he shared on the semantic level, rather than the syntactic level, to achieve that objective. An example of three parallel object hierarchies required for watershed management (WSM) will he demonstrated. The concept presented will provide an extension of GIS theory, and will formalize the link between semantically dissimilar hierarchies.