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 the irrigated cotton-growing areas of south eastern Australia, there is an increasing awareness for the need for land resource information and its importance for environmental management.

Knowledge of the quantity of water draining below the root-zone is necessary in order to maximise and ensure sustainable water use, particularly when surface water is applied for irrigated agricultural production.