Jonathan L. Goodall

Integrating Arc Hydro Features with a Schematic Network

A framework for integrating GIS features with processing engines to simulate hydrologic behavior is presented. The framework is designed for compatibility with the ArcGIS ModelBuilder environment, and utilizes the data structure provided by the SchemaLink and SchemaNode feature classes from the ArcGIS Hydro data model. SchemaLink and SchemaNode form the links and nodes, respectively, in a schematic network representing the connectivity between hydrologic features pertinent to the movement of surface water in the landscape. A specific processing engine is associated with a given schematic feature, depending on the type of feature the schematic feature represents. Processing engines allow features to behave as individual hydrologic processors in the landscape. The framework allows two types of processes for each feature, a Receive process and a Pass process. Schematic network features operate with four types of values: received values, incremental values, total values, and passed values. The framework assumes that the schematic network is dendritic, and that no backwater effects occur between schematic features. A case study is presented for simulating bacterial loading in Galveston Bay in Texas from point and nonpoint sources. A second case study is presented for simulating rainfall-runoff response and channel routing for the Llano River in Texas.

Component-based modeling of watershed systems.

Component-based modeling offers an attractive approach for constructing next generation watershed models. In component-based modeling, a complex system is represented as a series of loosely-integrated components with defined interfaces and data exchanges. Because components are loosely-integrated, it is possible for modelers to change how components are linked together within a plug-and-play environment. Component-based modeling is attractive for modeling watershed systems because watersheds are complex systems, and modeling such systems often requires the integration of data and models created and maintained by different groups. Component-based modeling allows for the integration of these disparate data and model resources, while still allowing each group to maintain and advance their own parts of the overall system. Although the component-based paradigm has been used to construct many software systems, it has only recently been applied for modeling watershed systems. Thus, in order to leverage this approach for modeling watersheds, important questions must first be addressed such as how watersheds should be decomposed into system components. In this paper we begin with a vision for component-based modeling, then focus on an experiment that seeks to understand how boundary condition data are exchanged between fully-coupled model components, and finally discuss future work needed to advance the use of component-based modeling of watershed systems.