Sedimentation-induced vulnerabilities of large reservoirs in India

Abstract

This study investigates sedimentation-induced vulnerabilities in large reservoirs across India, emphasizing the diverse geographical and hydrological factors influencing sedimentation dynamics. Reservoirs play a vital role in water supply, irrigation, flood control, and energy production, yet sedimentation significantly threatens their functionality, resulting in substantial capacity loss. Employing a robust statistical framework, this study estimates gross storage losses in large reservoirs (storage capacity > 100 MCM) and develops a bivariate joint probability-based Vulnerability Index (VI) to classify reservoirs across seven regions: the Himalayan Region (HR), Indo-Gangetic Plains (IGP), East Flowing Rivers (EFR1 and EFR2), West Flowing Rivers (WFR1 and WFR2), and Narmada–Tapi (NT). Our analysis reveals significant regional disparities in sedimentation impacts, with HR, WFR2, NT, EFR2, IGP emerging as the vulnerable regions due to steep terrain, high erosion, and monsoonal sediment inflows. Multiple reservoirs exhibit storage capacity losses exceeding 50%, severely undermining their ability to mitigate floods and manage droughts. The HR region shows the highest annual storage capacity loss among all regions, further emphasizing its critical vulnerability. By 2050, 10 reservoirs in EFR2 and 7 in WFR2 are projected to surpass 50% storage capacity loss, posing a severe threat to water security. Several reservoirs in HR, WFR2, EFR2, and IGP are classified as high or very high vulnerability, requiring immediate attention and management interventions. Overall, the study provides actionable insights for policymakers, ensuring the sustainable operation of reservoirs and strengthening resilience against water scarcity and climate change impacts.