IMPACTS OF CLIMATE CHANGE ON SURFACE WATER IN UPPER CAUVERY SUB-BASIN, INDIA

Abstract

Understanding how climate change affects river flows is crucial for devising effective strategies to adapt to and mitigate the vulnerability of water resources. The Soil and Water Assessment Tool (SWAT) is employed to simulate the impacts of climate change on the Upper Cauvery River in India. This study details the rigorous calibration and validation processes of the SWAT model, followed by its application in forecasting future climate scenarios using Shared Socio-Economic Pathways (SSPs). The Upper Cauvery River basin is an essential source of water for agriculture, energy production, and domestic use in southern India. However, the region is susceptible to the impacts of climate change, which threatens to disrupt these critical water supplies. As such, there is a pressing need to understand potential changes in river flow patterns and prepare for the future. The SWAT model was calibrated using data from 2003 to 2010, ensuring that the model accurately reflects the physical processes within the basin. Validation was then performed against daily streamflow data for eight years, followed by additional validation over seven periods from 2011 onwards. The model's performance was evaluated using various statistical indices, confirming its ability to simulate flow accurately. To project the impacts of climate change, four SSPs were utilized: SSP126 (Sustainability), SSP245 (Mid of the Road), SSP370 (Rivalry of Regional), and SSP585 (Development of Fossil Fuel). These pathways represent different future developments in demographics, economics, technology, and environmental policies. The SWAT model's projections for the period 2036-2065 indicate a significant difference in the average annual flow at the study area station, with variations ranging from approximately 21% to 38% across the SSP scenarios. These changes are attributed to alterations in precipitation patterns and temperature increases due to climate change. Looking towards the end of the century (2066–2100), the model anticipates runoff increases of 20.5%, 22%, 38%, and 36% for SSP2.6, SSP4.5, SSP7.0, and SSP8.5, respectively. These projections suggest more frequent and intense periods of high flow, potentially leading to challenges in water storage and flood management. The findings underscore the importance of incorporating climate change projections into water resource management planning. The variability in projected flows necessitates the development of adaptive strategies that can cope with both water scarcity and excess. This study provides valuable insights into the potential future trends of river flows in the Upper Cauvery River basin under different climate change scenarios. The use of the SWAT model in simulating these impacts aids in the development of informed water resource management strategies, ensuring the resilience of water supplies in the face of climate uncertainty.