Evaluating the relation between land use changes and the 2018 landslide disaster in Kerala, India

Land use and land cover changes (LULCCs) in mountainous areas may increase the susceptibility to landslides due to modifications of topography, vegetation, and material characteristics. Understanding the relation between LULCCs and landslide occurrences is important for landslide prevention and land resources management. In this study, these changes were analyzed for the landslides that were triggered during the 2018 monsoon event in Kerala, India. The changes in land use and land cover (LULC) that took place in a period of eight years prior to the 2018 event were analyzed for 4,728 landslide initiation points in the entire state, and for a subset of 2,223 landslides in the most affected district of Idukki. Apart from this, the initiation points were compared to those in steep areas and landslide susceptible zones. For these comparisons, we used LULC datasets for the period between 2000 and 2018 that were obtained from national organizations, derived from satellite image classification and visual interpretation. The LULC datasets lacked coherent classification schemes, so a standardization of LULC types was made. The results of these comparisons reveal that more than half of the landslides (58%) occurred in densely vegetated areas, and that 50% of the landslides that caused damage to buildings and roads originated in forest plantations, followed by built-up areas (25%). For most of the landslide locations (90% in Kerala and 83% in Idukki) there was no noticeable change in major LULC in the period prior to the event. Results of this study indicate that LULCCs for the the period 2010-2018 had less influence on the landslides occurred in 2018.