Determination of maize water requirement and crop coefficient using remote sensing data and SEBAL algorithm

The determination of maize water requirement and crop coefficient in Babol agrigultural research station in Mazandaran province using Landsat images and SEBAL algorithm was considered in the current study. Therefore, 11 satellite images of Landsat8 and Landsat7 during maize growth period in 2014 and 2015 were prepared. For using SEBAL, each band data was calibrated according to their corresponding coefficients. Then, net radiation flux on the ground surface and soil heat flux was calculated based on input and output radiation fluxes and computation of albedo, surface emissivity, ground surface temperature, and crop indices such as NDVI, SAVI and LAI. Sensible heat flux is also calculated by computation of friction velocity, aerodynamic resistance to heat transport and consideration of cold and hot pixels and atmospheric stability conditions. Finally, maize water requirement maps during growth period were prepared which had RMSE equals to 0.99, 1.09 and 0.65 mm/day compared to Reference Book, National Water Document and FAO56. Then, by computing reference evapotranspiration, maize crop coefficient in different growth stages was determined. This coefficient was 1.24 for mid stage which had 28, 8 and 3 percent difference with Reference Book, National Water Document and FAO56.