Estimating Pistachio Evapotranspiration using MODIS Imagery: A Case Study from Ardakan, Iran

摘要

Seasonal evapotranspiration (ET) of mature pistachio orchards in central Iran was estimated on a distributed basis by applying the SEBAL model to MODIS imagery. A downscaling approach was adopted to increase the spatial resolution of generated ET maps to a level that is useful for managing water resources in small-scale orchards of the region. SEBAL-ET for a sub-area of pistachio orchards was 1275 mm in 2012 growing season, significantly larger than the estimate obtained by applying a soil water balance analysis (759 mm). The difference may be attributed to the fact that soil water balance analysis was conducted for the top 1.2 m of soil, while tapping roots of pistachio can extract water from deeper layers. Assuming that SEBAL has provided accurate estimates, 82% of applied irrigation water was consumed through evapotranspiration process during pistachio growing season.