The Use of Unmanned Aerial Vehicle (UAV) Thermal and Multispectral Products in Quantifying Crop Water Use for Irrigated Barley Crop

Water scarcity in the biggest global concern particularly in arid environments with limited precipitation amounts. Irrigation in these regions becomes a solution to fulfil the crop water requirements. However, to achieve efficiency in irrigation, the balance between irrigation and evapotranspiration (ET) should be maintained. Irrigation should be applied to retain water accurate amounts of water that has been lost. However, quantification of these amounts requires high accuracy and has been done using remote sensing techniques utilizing coarse images which are unable to capture details at farm levels particularly those less than a hectare. This study aims at using high-resolution unmanned aerial vehicle (UAV) data to estimate actual evapotranspiration (ETa) based on thermal and multispectral datasets in an 18-ha barley cropped field. A Triangular Vegetation-Temperature Algorithm (TVTA) was used for this purpose. ETa was quantified successfully for three missions across different crop stages and validated using climate variables.