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.

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1. Ibrahim ‘Izzat Na’im, Ab Razak Mohd Shahrizal, Mat Desa Safari. A Short Review of Submerged Breakwaters. MATEC Web of Conferences 203, 01005 (2018), ICCOEE 2018.

2. Ranganath L.R, Krishna B. Hydraulic Investigations for Post Tsunami Impact at Hut Bay-A Case Study. Proceedings of HYDRO 2010 conference, ISH Journal of Hydraulic Engineering, Volume17, 2011, PP61-71.

    3. Nasrin Hassanpour, Javier L. Lara, Diego Vicinanza et al. Laboratory experiments on       transforming emerged into submerged breakwaters. Journal ofOcean Engineering,Volume 324, 30 April 2025, 120610.

4. Lamberti A, Archetti R, Kramer M, et al. European experience of low crested structures for coastal management.  Journal of Coastal EngineeringVolume 52, Issues 10–11, November 2005, Pages 841-866.

1. Borsje BW, van Wesenbeeck BK, Dekker F et al. How ecological engineering can serve in coastal protection. Ecol Eng 37:113–122. November 2011.
2. Sundar Vallam, Sannasiraj S A, Sukanya Ramesh Babu. Submerged Geosynthetic Reef as Shore Protection Measure for Islands.  Journal of Marine Science and Application March 2022, 21(1):128-139.

7. Nasrin Hassanpour, Javier L. Lara, Diego Vicinanza et al. Laboratory experiments on transforming emerged into submerged breakwaters. Journal of Ocean Engineering Volume 324, 30 April 2025, 120610.

1. Ranganath L.R, Krishna  B, Nagendra T. Mathematical model studies for silt mitigation measures for Essar Channel (EBTL) at Hazira, Gujarat on behalf of WAPCOS. CWPRS Technical Report-2012.
2. Barve K.H, Rahul S, Ranganath L.R. Mathematical model studies for wave tranquility and shoreline changes due to reclamation proposed by M/s.EBTL Hazira, Gujarat. CWPRS Technical Report-2020.
3. MIKE21- Flow Model FM. Hydrodynamics module and Sand Transport Module, DHI 2014.
4. SVASEK. Hydrodynamic and morphological simulation study for an approach channel of Essar at Hazira. Hydraulics report- 2009.

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.

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Ibrahim ‘Izzat Na’im, Ab Razak Mohd Shahrizal, Mat Desa Safari. A Short Review of Submerged Breakwaters. MATEC Web of Conferences 203, 01005 (2018), ICCOEE 2018.

2. Ranganath L.R, Krishna B. Hydraulic Investigations for Post Tsunami Impact at Hut Bay-A Case Study. Proceedings of HYDRO 2010 conference, ISH Journal of Hydraulic Engineering, Volume17, 2011, PP61-71.

    3. Nasrin Hassanpour, Javier L. Lara, Diego Vicinanza et al. Laboratory experiments on       transforming emerged into submerged breakwaters. Journal ofOcean Engineering,Volume 324, 30 April 2025, 120610.

4. Lamberti A, Archetti R, Kramer M, et al. European experience of low crested structures for coastal management.  Journal of Coastal EngineeringVolume 52, Issues 10–11, November 2005, Pages 841-866.

1. Borsje BW, van Wesenbeeck BK, Dekker F et al. How ecological engineering can serve in coastal protection. Ecol Eng 37:113–122. November 2011.
2. Sundar Vallam, Sannasiraj S A, Sukanya Ramesh Babu. Submerged Geosynthetic Reef as Shore Protection Measure for Islands.  Journal of Marine Science and Application March 2022, 21(1):128-139.

7. Nasrin Hassanpour, Javier L. Lara, Diego Vicinanza et al. Laboratory experiments on transforming emerged into submerged breakwaters. Journal of Ocean Engineering Volume 324, 30 April 2025, 120610.

1. Ranganath L.R, Krishna  B, Nagendra T. Mathematical model studies for silt mitigation measures for Essar Channel (EBTL) at Hazira, Gujarat on behalf of WAPCOS. CWPRS Technical Report-2012.
2. Barve K.H, Rahul S, Ranganath L.R. Mathematical model studies for wave tranquility and shoreline changes due to reclamation proposed by M/s.EBTL Hazira, Gujarat. CWPRS Technical Report-2020.
3. MIKE21- Flow Model FM. Hydrodynamics module and Sand Transport Module, DHI 2014.
4. SVASEK. Hydrodynamic and morphological simulation study for an approach channel of Essar at Hazira. Hydraulics report- 2009.