Patel, NR, Rakhesh, D, Mohammed, AJ (2006). Mapping of regional evapotranspiration in wheat using Terra/MODIS satellite data. HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES, 51(2), 325-335.
Adequate knowledge about consumptive use of water (actual evapotranspiration, ET) by wheat on a regional scale is a prerequisite in the intensively irrigated region of western Uttar Pradesh, India. Satellite observations supplemented with routine meteorological data provide a unique capability to estimate actual evapotranspiration over large areas needed for irrigation management and water balance. The surface energy balance algorithm for land (SEBAL) was applied to time series of MODIS level 3 data of reflectance and surface temperature measurements for estimation of actual ET on a pixel-by-pixel basis. Results showed that satellite observations with meteorological information could yield satisfactory estimates of spatially distributed ET in wheat. Actual ET estimates of wheat were found to be lower during the early crop growth period than during the peak crop growth and senescence stages. Remotely sensed estimates from SEBAL match the expected differences in ET values between open water bodies and wheat. The possible reasons for the large deviation in actual ET estimation using the MODIS sensor are the coarse resolution (1 km) of thermal bands and the lack of sunshine hours data to accurately estimate solar radiation as input. However, the free availability of standard MODIS products enables operational use for end-user applications related to agricultural water management.