Comparison of Aridity Indices in Mahi River Basin under Climate Change Scenarios

Climate change represents one of the most pressing global challenges of the 21st century, driven by a combination of natural climatic variability and intensified by anthropogenic activities. Since the advent of the Industrial Revolution, the accelerated emission of greenhouse gases (GHGs) particularly carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) has significantly contributed to global warming by enhancing the greenhouse effect, wherein long-wave terrestrial radiation is increasingly trapped within the Earth's atmosphere. The combined effects of these processes are increasingly visible worldwide, reflected in rising temperatures, shifting rainfall patterns, and more frequent extreme weather events. This warming has been exacerbated by unsustainable land and water resource exploitation, intensifying environmental degradation. Developing nations, often equipped with limited adaptive capacity, are particularly vulnerable to these changes. India, characterized by rapid population growth and development, faces pronounced risks, especially in critical sectors such as water resources. This study investigates shifts in aridity within the Mahi River Basin, a semi-arid, water-scarce region in western India with a catchment area of 34,842 km², under the influence of climate change. Historical (baseline: 1961–1990; present: 1991–2005) and future (2006–2040) dynamically downscaled climate datasets of precipitation and temperature were analyzed. Key parameters—rainfall, temperature, potential evapotranspiration (PET), and aridity—were evaluated across these periods. Results indicate a projected decline in rainfall, a rise in mean temperature, and an associated increase in PET, collectively contributing to heightened aridity and drier conditions in the basin over time. Evidence of climate change impacts is already discernible in the baseline and present.