Using Venus to Map Daily Evapotranspiration over Irrigated Agricultural in Arizona

Sustainability of irrigated agriculture in the U.S. Southwest is threatened by water shortages and the challenge of managing salinity. One way to reduce the threat and improve crop water management is to use remote sensing observations to help map daily evapotranspiration (ET) at fine spatial scales. The maps, when combined with crop growth forecast models and local management expertise, can improve crop water management, ET forecasting, and irrigation scheduling. The Venus mission has capabilities to realize these improvements in three ways: 1) its high frequency observation periodicity enables nearly daily charting of crop cover and leaf area, 2) its high spatial resolution (5-10 m) provides detail that makes possible crop monitoring and management within fields, and 3) Venus’ multispectral capability resolves canopy density variations not feasible with conventional NDVI-based mapping.

Since 2018 we have been using Venus to track crop growth and ET over crops grown in two significant irrigation districts in Arizona: Yuma, where over 80% of leafy greens are grown for North America during winter months, and in the Ak-Chin Indian Community, where long season crops such as cotton, alfalfa, corn and potato are grown. Differences between ET and cover mapping results using conventional and Venus satellite data will be shown.