Environmental Controls on Evapotranspiration Partitioning in a Semi-Arid Agricultural Region of Telangana, India

Seasonal variations in environmental conditions strongly influence evapotranspiration (ET) and its components, evaporation (E) and transpiration (T), thereby directly affecting agricultural water use. Understanding how these environmental factors regulate ET dynamics is essential for improving water management in semi-arid agricultural regions of India. The study is carried out in Sangareddy district of Telangana, India during the Kharif and Rabi seasons (2024). ET was estimated for both Kharif and Rabi seasons using satellite-based energy balance modelling and divided into its E and T components. To comprehend their impact on surface–atmosphere interactions and crop water consumption dynamics, the seasonal environmental impact on ET is analysed in connection to shifting climatic conditions. Temporal variations of major variables including air temperature (Ta), vapour pressure deficit (VPD), solar radiation (Rs), and precipitation (P) are investigated in this study. Cumulative precipitation distribution during establishment, flowering, growth, and maturity stages of the crop is estimated and compared with average crop water requirement. Furthermore, highlighting the need for irrigation, particularly during the establishment and flowering stages, avoiding crop water stress was observed. During the crop cycle in both seasons, mean leaf area index (LAI) and soil moisture content were also evaluated for the studied region. The analysis shows a significant seasonal contrasts in ET magnitude and its partitioning, with transpiration dominating during peak crop growth under favourable moisture conditions, while evaporation contributed more during early growth stages and dry spells. The results demonstrate that, higher air temperature, vapour pressure deficit, and solar radiation during the Rabi season enhanced atmospheric demand, leading to increased irrigation requirements, particularly during establishment and flowering stages. Thus, these findings emphasises the utility of satellite-based ET partitioning for identifying water-stress-prone growth stages and optimizing irrigation strategies in semi-arid agricultural regions.

Keywords: Evapotranspiration; ET partitioning; environmental variability; satellite imagery'; semi-arid agriculture