Spatial Variability in Evapotranspiration Related to Irrigation System Distribution Uniformity
Understanding the causes of variable ET in a field is critical for maximizing yield on a per-acre basis as well as for proper irrigation scheduling and regional water management. Since 2004, the ITRC has provided technical irrigation support and management for over 2,000 acres of center pivot irrigated forage crops being supplied by reclaimed water near Palmdale, California. Irrigation scheduling is conducted using a daily soil water balance dual crop coefficient approach. Detailed records on planting and harvest dates, daily water applications, pivot run speeds, and annual distribution uniformity evaluations are maintained along with daily reference evapotranspiration data from a station on site. Since accurate records on pivot distribution uniformity are available, and most of the pivots were under moderate deficit irrigation in one of the years analyzed, a portion of the spatial variability in ETc can be attributed (quantifiably) to this non-uniformity in irrigation distribution.
Howes, D.J., L. Hoffmann, and F. Gaudi. 2012. Spatial Variability in Evapotranspiration Related to Irrigation System Distribution Uniformity. Presented at 2USCID Conference on Managing Irrigation Systems in Today's Environment, Reno, Nevada, November 13-16, 2012. 13 pp.
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