The add and semi-add regions of the world are being relied upon to provide increasing amounts of agricultural products. This is being facilitated by the increasing dependence on irrigation. In many cases irrigation inefficiency has led to water loss through deep drainage (DD) and groundwater recharge. In the irrigated cotton-growing areas of southeast Queensland and north western New South Wales, irrigation efficiency is increasingly becoming an important natural resource management issue because of the increasing number of instances where perched water tables are causing problems with respect to water logging and in isolated instances soil salinisation (Triantafilis et al 2002).