Reports and Papers

Fedra, K. and Jamieson, D.G.
An object-oriented approach to model integration: a river basin information system example. In: Kovar, K. and Nachtnebel, H.P. [eds.]: IAHS Publ. no 235, p669-676.


This paper describes the WaterWare system, an object oriented information and decision support system for river basin management. The basic data framework combines a hybrid GIS as the overall structure with classes of objects, including river basin elements, models and model scenarios, and tasks or decision problems.

River basin elements are spatially referenced, and represent, for example, subcatchments, reservoirs, treatment plants, river reaches, etc. From the GIS perspective, they are polygons, lines, points, or regular cell grids. Their state, in a context defined by other objects in the system, is determined by a set of methods, which are models or sets of rules for an embedded expert system.

Tasks are specific, problem oriented views of river basin objects or combinations of objects. They present their state, usually over time, given a number of decision variables or scenario assumptions, to the user to support planning or management decisions.

The various objects are linked explicitly, eg., a reservoir might be linked to the subcatchment that provides its inflow, an observation station that monitors the hydro-meteorological data, and an irrigation district it supplies. Models such as a rainfall-runoff model or an irrigation water demand estimation model are used to update the state of these respective objects, and thus provide inputs (time series of demand or supply) to a water resources model. The water resources model, in turn, provides input to a water quality model, that again operates in the context of other objects such as discharge nodes (treatment plants, industries, municipalities), or extraction and monitoring points.

Models are embedded, as methods, with the respective objects. Rules are used to configure the scenarios and estimate parameters. The models' operation can either be transparent, when a task requires an update on an object, or explicit, when the task is defined in terms of model scenario analysis.

The GIS, with the underlying spatial data such as land use, geology, and topography, also provides the display functions; spatial model output is dynamically mapped onto the map background as animated topical map coverages. Textual, numerical, and pictorial attributes of an object, and meta data providing background information to the user, are accessible through a multi-media hypertext system, that objects use to present themselves to the user. GIS, data base, and model interface are thus fully integrated, and present a unified graphical and symbolic representation of a river basin to the user. This interface supports an easy to learn, exploratory and experimental access to a large and complex information and decision support system. The multi-media nature of the system's interface also makes its extension into a networked client/server version for access through the World Wide Web straightforward.

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