Simplifying environmental model reuse

The environmental modelling community has developed many models with varying levels of complexity and functionality. Many of these have overlapping problem domains, have very similar 'science' and yet are not compatible with each other. The modelling community recognises the benefits to model exchange and reuse, but often it is perceived to be easier to (re)create a new model than to take an existing one and adapt it to new needs. Many of these third party models have been incorporated into the Agricultural Production Systems Simulator (APSIM), a farming systems modelling framework. Some of the issues encountered during this process were system boundary issues (the functional boundary between models and sub-models), mixed programming languages, differences in data semantics, intellectual property and ownership. This paper looks at these difficulties and how they were overcome. It explores some software development techniques that facilitated the process and discusses some guidelines that can not only make this process simpler but also move models towards framework independence. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.