Remote sensing-based assessment of Varkala cliff retreat in Kerala, India

Coastal cliffs are dynamic landforms that are constantly changing due to natural and anthropogenic factors. Continuous monitoring of the vulnerable cliffs is crucial to understanding their stability and developing effective strategies for managing coastal areas. An attempt to understand the retreat rate and extent of the Varkala cliff, Kerala - a geo heritage site and its contributing factors were investigated in this study. Remote sensing and GIS analysis through satellite imageries were employed to estimate the retreat. The results indicated that the Varkala cliff has retreated significantly over the past few decades, with rates of erosion varying along the length of the cliff. The causative factors that govern the retreat; such as urbanization, and geological and hydrology forces were examined. The cliff recession based on sea level rise is also examined. The findings indicate that human activities, particularly the expansion of urban areas along the cliff, have played a significant role in accelerating the retreat of the Varkala cliff. Additionally, variation in the cliff morphology has influenced the rate and pattern of retreat. The importance of considering the complex interactions between natural and anthropogenic factors in understanding cliff erosion and retreat was highlighted. This study provides important insights into the factors driving cliff erosion in Varkala. This will help develop coastal management strategies that can preserve its geological and ecological value for future generations.