Interplay Between Tidal Range and Dam-Induced Flooding in Sustaining the Islands and Livelihoods in Narmada Estuarine Zone, India

Development of channel cut-off estuarine islands is a complex phenomenon influenced by various factors. This study focuses on understanding the interplay between channel discharge and tidal surge in causing morphological variations in lower fractal peninsular rivers. Using the case study of Taria Island in the Narmada Estuary, we investigate the temporal development of the island and river bank line changes. This study underscores the importance of considering multiple factors, including tidal energy and sediment dynamics, in understanding the formation and evolution of estuarine islands. The integration of remote sensing techniques and field observations allows for a comprehensive analysis of the complex processes driving morphological changes in estuarine environments. Multispectral and RADAR-based remote sensing data at 30 m resolution are utilized to assess the role of tidal influx in facilitating the convergence of suspended sediment load. The Normalized Difference Water Index (NDWI) is employed to illustrate the seasonal mechanism of sediment stabilization in the channels. Our findings reveal an inverse relationship between stream discharge during non-monsoon months and sediment accumulation attenuated by tidal pivoting. Through the interpretation of remotely sensed data, we conclude that the large amplitude of the tide in the Gulf of Khambhat region provides the necessary energy for sediment accretion in the channels south of the island, resulting in a raised riverbed on one side and contributing to the enhancement of the island area. These findings contribute to a better understanding of the interactions between hydrological and geomorphological processes in estuaries, highlighting the significance of tidal energy in shaping estuarine landforms and promoting sediment deposition.