ESTIMATION OF ACTUAL EVAPOTRANSPIRATION USING SEBAL REMOTE SENSING METHOD

Abstract

Evapotranspiration (ET) plays a crucial role in the hydrologic cycle, which highlights the necessity of precise ET assessment for the management of water resources. Remote sensing methods are widely used for ET estimation at regional spatial scale. Proficiency in digital image processing techniques and the energy balance equation are prerequisites for estimating spatial ET. The goal of the present study was to estimate the actual ET in the Haridwar district of Uttarakhand during the Rabi season. The study sought to create a reliable model for automating the estimation of actual evapotranspiration (ETa) by contrasting it with the easily accessible data, such as METRIC ET. The study aimed to develop a dependable approach by utilizing five Landsat 8 satellite images taken between mid-November and mid-April, with a maximum cloud cover of 9%. The SEBAL model results showed some interesting trends: the daily actual ET (ET24) values were recorded near the end of the season, especially in April, when they reached 5.87 mm d−1. These values were almost the same as the METRIC estimate of 5.51 mm d−1, with a few minor variations. On the other hand, the season's lowest ET24 values were recorded in the beginning of November, roughly 2.55 mm d−1 according to the METRIC model and 2.53 mm d−1 according to the SEBAL model. This comparison highlights the consistency in their estimations and the association between the data from the METRIC and SEBAL techniques. This research aims to improve our knowledge of evapotranspiration dynamics during the Rabi season in the Haridwar district by automating the ETa estimation process and comparing it with well-known models such as METRIC. The study would provide important insights for water management in agricultural sector.