Application of SEBAL approach and MODIS time-series to map vegetation water use patterns in the data scarce Krishna river basin of India

Evapotranspiration (ET) from irrigated land is one of the most useful indicators to explain whether the water is used as "intended". In this study, the Surface Energy Balance Algorithm for Land (SEBAL) was used to compute actual ET from a Landsat7 image of December 29, 2000 for diverse land use in the Krishna Basin in India. SEBAL ET_a varies between 0 to 4.7 mm per day over the image and was quantified for identified land use classes. Seasonal/annual comparison of ET_a from different land uses requires time series images, processed by SEBAL. In this study, the Landsat-derived snapshot SEBAL ET_a result was interpreted using the cropping calendar and time series analysis of MODIS imagery. The wastewater irrigated area in the basin has the highest ET_a in the image, partly due to its advanced growth stage compared to groundwater-irrigated rice. Shrub and forests in the senescence phase have similar ET_a to vegetable/cash crops, and ET_a from grasslands is a low 0.8 mm per day after the end of the monsoon. The results indicate that wastewater irrigation of fodder and rice is sufficient to meet crop water demand but there appears to be deficit irrigation of rice using groundwater.