Satellite-based ET mapping to assess variation in ET with timing of crop development

Evapotranspiration (ET) from irrigated agriculture is an important issue in arid and semi-arid regions where it has large impact on water resources depletion and water management. Satellite-based remote sensing is a robust, economic and efficient tool for estimating actual ET from irrigated regions and for developing crop coefficient (Kc) curves. The technique can cover hundreds of sampled fields at a time so that large populations of ET and Kc can be used to develop representative mean values. This paper uses a satellite remote sensing technique to analyse the impact of planting and development schedules of crops on ET for crops of dry beans, corn, potatoes, sugar beets and small grains (wheat and barley), which are major crops in the temperate, semiarid climate of southern Idaho. The results indicate that early planted and developing crops consume 6–10% more water in the southern Idaho environment than late developing crops for most major crop types. This increase occurs primarily because early developing crops tend to have a relatively longer growing period than crops developing later in spring. ET quantified through this procedure may have application in evaluating irrigation/project performance and in determining economic productivity of water.