CMSS: policy analysis software for catchment managers

This paper describes a computer program that analyses the likely effects of proposed land use and land management policies on the nutrient loads delivered to rivers. The program was designed to meet the needs of catchment management groups that are developing policies and this perspective led to the inclusion of some novel features in the program. These features include a contextual database, a language for representing policies and a simple explanatory capability in the model. A very simple model is used to predict nutrient loads. The paper describes the formalism of the model, the syntax for expressing policies and the link between these policies and the model.