ASSESSMENT OF IRRIGATION PERFORMANCE AT REGIONAL AND PROPERTY SCALE

A method is described by which irrigation performance on a whole farm scale can be assessed from readily available data, using an annual water balance approach. The method is demonstrated using data from horticultural properties in the South Australian Riverland and the New South Wales and Victorian Sunraysia regions. The data used in this method is readily available, and includes crop survey data, annual pan evaporation and rainfall data, and water meter readings collected by water authorities. A method was selected which allowed the comparison of total water volumes (irrigation plus rainfall) applied to properties with the annual crop water requirements of plantings on those properties. Annual Water Balance Efficiency (AWBE) is a direct measure of the estimated annual water requirement of the crops present on a property as a proportion of the total annual volume of water applied to that property as rainfall and irrigation. This figure can be used as a measure of an irrigator or region’s performance. Annual Water Balance (AWB) accounts for all water moving to and from the property, and estimates the extent to which the water applied was in excess or deficit to requirements. Excess application is an estimate of drainage past the rootzone, and can be summed to give an estimate of average drainage depth and total drainage volume produced within a region. Deficit indicates crops being placed under some level of stress. Storage of data in a GIS platform facilitates the visual comparison of performance between irrigators on the basis of irrigatio