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By: Boora Krishna and Jiweshwar Sinha.
Central Water & Power Research Station, Pune, India
Abstract
Among various engineering interventions, submerged breakwaters (reefs) have emerged as a promising solution that balances shoreline protection with environmental and aesthetic considerations. This paper presents a study at Essar Bulk Terminals Limited (EBTL), Hazira, Gujarat, on the effectiveness of a reef in protecting reclaimed areas from wave and tidal action, as well as mitigating sediment accumulation in the navigational channel within the Tapi Estuary on India’s west coast. A reef structure measuring 300 meters in length and 80 meters in width, with a crest elevation of +3.5 meters relative to Chart Datum, is proposed at the southeast corner of the reclaimed area to address persistent erosion and sedimentation issues. Numerical investigations were carried out using the MIKE 21 Flexible Mesh Software to simulate flow conditions in coastal and estuarine areas with complex geometry. The model studies include calibration of the model for the existing site conditions, and various alternatives(with and without Reef) for the proposed condition to overcome/minimize the recurrent problem of erosion at south-eastern corner of the reclamation and eroded material being deposited in the navigational channel, leads to the formation of sediment hump. Hydrodynamic and sediment transport modelling results reveal that the inclusion of the reef significantly reduces erosion of reclaimed area and sediment deposition in the navigational channel. Notably, the proposed configuration is projected to reduce sedimentation by approximately 0.45 Mm3 in the navigational channel overall, and by about 1.35 Mm3 specifically in the hump area, demonstrating the effectiveness of the reef as mitigation measure.
Citation:
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