SURFACE IRRIGATION PERFORMANCE IN THE UPPER TUNUYÁN RIVER BASIN MENDOZA, ARGENTINA

Abstract

The irrigated area in the Upper Tunuyan River Basin comprises 41,601 ha with surface irrigation rights. It is, therefore, essential to develop indicators to determine irrigation water use efficiency -which will, in turn, help to detect the main problems and find solutions for the sustainable development of the basin. The overall objective of this study is to obtain information on irrigation water use within the agricultural properties in the command area of the Upper Tunuyan River and to determine the potential efficiencies to be achieved considering possible operational changes and salt balance. Surface irrigation methods, with and without tailwater runoff, prevail in the basin. Walker and Skogerboe's methodology (1987) and the ASAE standards (1999) were used. Soil and irrigation characteristics include: furrow irrigation with runoff; sandy-loam soil textures; 0.87% slopes; soil salinity from 0 to 100 cm: 1.12 dSm -1 ; irrigation water salinity: 0.70 dS m ; managed and unit flows of 53 L s -1 and 1.24 L s -1 m -1 respectively; 123 m long irrigation plots; 7-h application periods; and 5.3 mm h -1 basic soil infiltration. The following results were obtained: on-farm irrigation efficiency; and conveyance, application, storage and distribution efficiencies: 91, 43, 99 and 91%, respectively. Potential efficiency may rise to 68% if plot irrigation management is improved; it may well be higher than 68% if the salt balance is taken into account.