Assessment of beach morphological changes in the east coast of India during cyclone Phethai, through field data and numerical modeling

Abstract

Episodic extreme waves caused by cyclones can have catastrophic consequences for coastal zones, including drastic beach morphology changes. The present study analyzed the beach morphological changes from Kakinada to Konapapapeta on the southeast coast of India before, during, and after the tropical cyclone Phethai using field survey and numerical modeling. Beach profiles were collected using Trimble RTK GPS and shoreline tracking was performed with handheld GPS. Numerical modeling was carried out using MIKE software to estimate the sediment transport rate before, during, and after the cyclone. Although the intensity of the cyclone reduced to a deep depression before landfall, several morphological changes were observed. Erosion was higher in the northern sector, where the beach width was less, and prominent scarps were seen throughout this region after the cyclone. The inundation varied from 40 to 120 m during the cyclone due to a storm surge of 0.5 to 1 m. During the cyclone, significant wave heights reached up to 4 m. The gross sediment transport rate is 3 to 13 times greater during the cyclone period than during the non-cyclone period. The maximum gross sediment transport rate during the Phethai cyclone was 1040 m³/day. Sediment transport was estimated for the same site for the non-cyclone year 2019, and the gross transport rate was 26,174 m³. As it is projected that extreme events are likely to increase due to climate change, output from this type of study is vital to environmental managers to assess erosion and develop long-term mitigation plans.

Keywords:

• Beach profiles
• gross sediment transport
• numerical modeling
• tropical cyclone
• wave data

Acknowledgements

The authors are grateful to the project scientists Ateeth Shetty and Buckle S, who accompanied us during the fieldwork conducted during this cyclonic event. The authors are thankful to the Ministry of Earth Sciences, Govt. of India for implementing the Project ‘Sediment transport estimation selected sites along Indian coast’ at the National Centre for Coastal Research (NCCR), Chennai. The authors are immensely thankful to Dr. Sanitha K. Sivadas, Scientist D, NCCR for her support in improving the language of the manuscript. The authors express sincere appreciation for the invaluable contributions of the anonymous three reviewers, whose critical comments and suggestions considerably aided in enhancing the quality and substance of the paper.

Authors’ contribution

V. Noujas—conceptualization of work, paper writing, field work and editing the paper. R.S. Kankara—Guidance for paper writing and reviewed the manuscript. B. Rajan—Prepared some of the figures and participated in fieldwork.

Data availability statement

All the data presented here is with the corresponding author (Dr. Noujas V) and can be produced based on request.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by Ministry of Earth Sciences.