Zone-Wise Estimation and Spatio-temporal Variability of Potential Evapotranspiration in Maharashtra Using the Thornthwaite Method
Parveen Kumar *
Department of Agricultural Meteorology, CCS Haryana Agricultural University, Hisar, 125004, India.
P.R. Jaybhaye
Department of Agricultural Meteorology, VNMKV, Parbhani, MH, India, 431402, India.
Suresh
Department of Agricultural Meteorology, CCS Haryana Agricultural University, Hisar, 125004, India.
Yogesh Rajrana
Department of Agricultural Meteorology, CCS Haryana Agricultural University, Hisar, 125004, India.
Meenakshi Devi
Department of Entomology, SGT University, Gurugram, India.
Ronak Singh
CCS Haryana Agricultural University, Hisar, 125004, India.
Surendra Singh Shekhawat
Department of Entomology, Faculty of Agricultural Sciences, SGT University, Gurugram 122505, India.
*Author to whom correspondence should be addressed.
Abstract
Potential evapotranspiration (PET) is a fundamental parameter of the hydrological cycle, reflecting atmospheric water demand and serving as a critical input for irrigation planning, drought assessment, and climate change impact studies. This study evaluates the zone-wise estimation and spatial variability of PET across nine agro-climatic zones of Maharashtra, India, over the period 1991–2020, using the Thornthwaite method. Long-term daily temperature data were utilized to calculate PET, and annual and inter-annual variations were assessed to capture spatial heterogeneity and temporal dynamics. Results indicate substantial spatial variability, with mean daily PET ranging from 3.75 mm day⁻¹ in the Western Maharashtra Plain to 5.70 mm day⁻¹ in Central Vidarbha, highlighting higher atmospheric water demand in semi-arid inland regions and lower demand in the Western Ghats and Konkan coastal areas. Temporal analysis revealed moderate inter-annual fluctuations, with PET peaks corresponding to drought-prone and high-temperature years, reflecting sensitivity to regional climatic variability. These findings are consistent with observed patterns in semi-arid and humid regions reported in prior studies. The study demonstrates the suitability of the Thornthwaite method for long-term, large-scale PET estimation in data-scarce regions and provides zone-specific insights for targeted irrigation scheduling, water resource management, and climate-resilient agricultural planning in Maharashtra.
Keywords: Potential evapotranspiration, Thornthwaite method, agro-climatic zones, Maharashtra, spatial variability, climate variability, irrigation planning