A Modelling Framework Incorporating a Map Algebra Programming Language

The paper presents a modelling framework to integrate dynamic analysis and spatial analysis, and to apply this to a hydrological application. The dynamic analysis runs a simulation of a set of process modules. Modules for spatial analysis functionality are implemented in software libraries, or components. Currently we support components for a map algebra language called MapScript, and for spreadsheet calculations using Excel. An important issue in environmental models and in any modelling framework is dealing with different scale processes. When processes occur over different time or spatial scales but are still integrally related, this becomes a problem for applying efficient modelling solutions. The paper reviews two common strategies for solving this problem, namely multistep and multigrid methods. Because of the heterogeneous nature of landscapes processes neither is seen as offering a satisfactory solution. We have tried a variant to a multistep solution by allowing the user to specify the timing of different processes that occur in a landscape model. The paper describes the modelling framework and language specification used to describe module execution. The specification is written in XML to leverage its widespread use in web computing environments. The modelling framework may be used for diverse modelling applications in hydrology, landscape assessment, geomorphology and ecology. The paper will demonstrate a mock hydrological application to model runoff in a small watershed.