Geological Records of Past Cyclones Preserved in the Beach Ridge Systems on the East Coast of India

The Bay of Bengal is a well-known hotspot for cyclone formation. Multiple recent cyclones, such as the Odisha Super Cyclone in 1999 and Cyclone Fani in 2019, along with a series of historical cyclones, have severely impacted the east coast of India, particularly the coastal regions of Odisha and West Bengal States. However, the existing cyclone record from the area is insufficient for multi-decadal recurrence analysis, rarely extending beyond last few decades. Hence, understanding and integrating historical, prehistorical, and geological cyclone records from the area can provide information on the social, economic, and environmental impacts of cyclones. This information will aid in planning response strategies and implementing policies to mitigate cyclone effects. This study investigates the geological record of cyclones buried in the prograded beach systems near Konark in Odisha over the past few hundred years. Shore-normal ground penetrating radar (GPR) reflection profiles were collected using the 250 and 500 MHz antennas of the pulseEKKO PRO GPR system. Sediment cores and excavated faces were analysed along the same GPR lines, and optically stimulated luminescence ages provide a chronological framework over the last 300 years. Processed GPR profiles exhibit a number of high-angle erosional surfaces. These surfaces were likely caused by erosion during severe cyclones in the region, spanning at least the last three centuries. Eight such erosional surfaces were identified from the GPR profile near Konark. Trench and core data from the swales also highlight several distinctive layers rich in heavy minerals, possibly the result of repetitive cyclones in the area. One prominent sand layer gives an interim age of 150 years, likely linked to a late 19^th century washover event. The data presented in this study indicate that geological records can be used to build a long-term cyclone record for the area. Given the increasing population density in the region, a comprehensive cyclone record can provide valuable insights into the changes in frequency and intensity over the long term, which can be used to inform decision-making processes for coastal management and development.