Time-series analysis of erosion issues on a human-intervened coast– A case study of the south-west coast of India

Abstract

Coastal erosion has long been identified as a cause of concern for the state of Kerala, situated in the Indian subcontinent, affecting the life and livelihood of millions residing in the coastal belt. The increased human interference supplemented by changes in the climatic pattern in recent years has modified the coastal scenario of the state altogether. The present study attempts to evaluate the effect of anthropogenic influences in modifying the coastal scenario to review the efficiency of the coastal management policy adopted by the state over the years. For this purpose, the shorelines extracted from the available multi-temporal satellite images are analysed using DSAS software to calculate the shoreline change rate prior to 2000 (1973-98) and post-2000 (2002-21) using the linear rate of regression method. The study seeks to key out critically eroding areas, subsequently exploring the possible conducive reasons for the changed coastal scenario. The results indicate a reduction of 34.5% in the share of eroding length, with a visible shift in a substantial portion of coastal stretch from the mild erosion category to the stable category. Despite the state's continuous efforts to curb the issue, the long-term shoreline change over the past 49 years (1973–2021) reveals erosion to be dominant in nearly 39.12% of the coastal length, with the share of eroding length in the southern, central and northern regions as 33.8%, 38.67% and 44.04%, respectively. The results point towards the dominance of human interventions accompanied by climate change impacts as the primary reason for transforming the coast, necessitating the need to modify the state's current coastal management policy. The research emphasises the need for a comprehensive coastal management plan for the state to take heed of the changing climatic scenario.