Integrated Assessment of Evapotranspiration, Soil Moisture, Climate Variability and LULC Dynamics in the Ramganga River Basin, North India

Evapotranspiration (ET) is a key part of the terrestrial water cycle, especially in river basins reliant on agriculture, where climate change and land use impact water resources. This study examines long-term ET trends in the Ramganga River Basin of the sub-Himalayas for 1995 to 2024, linking them to land use changes and land cover-related meteorological factors. The average ET during this period was 766.74 ± 38.95 mm/year (CV = 5.08), with a low of 692.08 mm/year in 1998 and a high of 888.84 mm/year in 2024. The Mann–Kendall test indicates a significant upward trend (τ = 0.430; Z = 3.31; p = 0.000905), and the Pettitt test identifies 2005 as an abrupt change point (p = 0.0148), dividing the period into ET-anomaly years (1995–2004) and later years (2006–2024). Land use change analysis from 2017 to 2024 revealed notable shifts in agricultural and urban areas, leading to declines in natural vegetation. The area of cultivated land increased by 11.17%, that of grassland expanded by 21.85%, that of forestland decreased by 29.12%, and that of urban areas increased by 14.49%. Correlation studies of ET drivers revealed that tree ET depends primarily on temperature, whereas the temperature dependence of crop ET became more pronounced from 2017 to 2024, which is consistent with increased cropland. These findings suggest that hydroclimatic regime shifts in the Ramganga watershed after the mid-2000s were driven mainly by agricultural intensification and irrigation practices rather than climate change alone. The results highlight the importance of accounting for land use impacts in water resource planning.