<p>The Penna region in India is a semi-arid catchment area affected by climate change and land-use changes, impacting its watershed hydrology and ecological variations, due to continuous anthropogenic activities. Understanding these impacts is crucial for sustainable development, with land use being a significant factor. This paper aims to evaluate the effects of land use and climatic changes on Ecosystem Vulnerability in the Upper Pennar River basin, India. SWAT model was developed to analyse those impacts for two scenarios RCP 4.5 and RCP 8.5. The scenarios represent the radiative forcing of medium to high levels of greenhouse gas emission towards describing the future. Different types of data were collected to develop the SWAT model for the past years 1985–2023 and predicted for the years 2030, 2050, 2075 and 2100. An artificial neural network (ANN) and the Markov chain algorithm were used for transitional changes between land-use classes, and cellular automata simulation predicted plausible future land-use cover, validated against 2023 data with an accuracy of over 80%. The Land Change Modeler (LCM) revealed that water bodies are expected to increase in the century, whereas the deciduous forest, built up land and fallow land decrease. The significant observation is that for the combined effect of Land use Land cover, and climate change, the water yield is likely to decrease by 20% by 2030 and it is expected to increase up to 227% by 2100. Similarly, the rainfall is likely to increase in both the scenarios. By understanding the interplay between Land use, Land cover and climate factors, the performance of hydrological models can be improved, and can work towards sustainable development and safeguarding the ecosystem.</p>