Each booklet in The Basics of Recharge and Discharge series covers a specific technique for detecting, measuring or modelling groundwater recharge and discharge. Part 10 provides an overview of the use of plot scale models in estimating deep drainage. This booklet explains how such models can add understanding to deep drainage studies. It describes the different broad types of plot-scale models that are available and how they can be most appropriately used. Throughout the booklet, clear examples demonstrate the potential applications for a range of simulation models. They contrast the features and capabilities of the models and illustrate what can be achieved through modelling. The chapter finishes by describing how to test models and where to find more information on the models most commonly used in Australia.