Modelling process overview

This page is intended to give an overview of different aspects of the modelling process, particularly in the context of how they interact with model structure decisions and modelling software tool selection. Here 'model structure' refers to things like how the catchment is broken up into modelled units, such as subcatchments or smaller units representing areas of a particular land cover type, and how different units are connected in the model. Structure choices are linked to the choice of 'modelling software tool', such as WRSM-Pitman, ACRU, or SWAT, because different modelling tools allow for different kinds of structures and process representation. There can be multiple modelling tools that will be able to meet certain structure needs and wants in some cases, while in other cases no tool may meet them all. There are other considerations, such as ease of use, that will contribute to modelling tool selection. There is never enough time and data to build "the perfect" model and compromises will always need to be made. Identifying 'needs' and 'nice-to-haves' in as much as possible early on will assist in appropriate, 'fit-for-purpose' tool selection.

The process of catchment modelling is generally not linear. The sections given below don't imply steps that are necessarily completed sequentially; there will often be iterations and circling back for revising.

Defining the modelling project goal(s)

The purpose of the modelling project will impact what

Conceptual model

Input data

Selecting a model structure

Selecting a modelling tool