Two different remote sensing techniques for monitoring crop coefficient and water requirement of cotton

Crop coefficient of cotton is estimated using two remote sensing techniques: an energy balance approach (SEBAL) and a reflectance-based method (K-cbrf). The results are compared with tabulated values in the FAO-56 paper, as well as the K-c values developed by the US Bureau of Reclamation (USBR) to be used in the "Lower Colorado River Accounting System (LCRAS)." Crop coefficients from all four sources (SEBAL, K-cbrf, FAO-56, and LCRAS) are analysed to approximate daily and seasonal water requirement of cotton for the growing season of 2008. The results show that both FAO-56 and LCRAS underestimate cotton irrigation demand due to assuming a shorter growing season and ignoring a heavy pre-irrigation event. Remotely sensed estimates of water requirement were also validated using actual irrigation depth data.