Estimation of Evapotranspiration for Seasonal Water Usage Analysis

This paper focuses on estimating Evapotranspiration over the Cauveri river basin in Mandya District of Karnataka, India (12° 31'N, 76°53'E), using LANDSAT-8 satellite data. ET will indicate the amount of water loss from that particular land surface, and in turn, this can be used for water budget analysis. Accurate estimation of evapotranspiration (ET) is essential for the proper water usage analysis. Evapotranspiration estimation using hydrological methods, micro-meteorological methods can only be considered as point measurements for smaller areas. Extrapolation of ET rates over a larger area using point data has limited accuracy. Airborne or satellite images using remote sensing techniques are practical method for developing ET spatial variation at a regional scale. In this paper, we provide an analysis of ET estimation using Landsat-8 data during Jan & Feb 2018 for the identified study area. The reason for choosing this area is that a significant part of the land cover of Mandya district is under agricultural use. We propose Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC) - a satellite-based image-processing model for calculating ET as a residual of the surface energy balance. The study indicated that the Normalized Vegetation Index (NDVI) and Land Surface Temperature (LST) are inversely proportional to each other, indicates that as temperature increases, vegetation index decreases.