Coastal Habitat Vulnerability of Southern India: a multiple parametric approach of GIS based HVI (Habitat Vulnerability Index) model

Abstract

The southern-most coast of India gently sloped southwards, which comprises the landforms like sandy beaches, dunes, estuaries, and other fluvio-marine landforms. During the past two decades, the rapid growth of population leads to serious environmental problems of the coast such as erosion, deformation of coastal landforms, aquifer contamination causing damages to habitat. We perform the Habitat Vulnerability Index (HVI) for demarcating vulnerable zone to habitat impairment by analyzing multiple physical, environmental and social variables. The algorithm in this model uses weighted vulnerability score of feature classes of each variable and combination of variables to facilitate computation of thresholds to calculate pixel-based vulnerability rate by averaging the weighted values using ArcGIS software. The result of the HVI model has estimated index values between 8 and 52 with a mean vulnerability index value of 30. Based on the range of HVI values, we categorize the coastal zones into five classes such as very low or protected zone, low vulnerable, moderately vulnerable, high vulnerable and very high vulnerable zones. Out of the total area, 9% of the coastal areas fall into the category of very high vulnerability conditions. It distributes the coastal habitats such as salt marshes, sand dunes, estuaries, brackish water, and cliffs within the area. Estuaries and its associated landforms are active shelters for numerous species in the coastal and marine habitats. Human settlements along the low-lying areas (elevation less than 10 m) of the Inayamputhenthurai, Mandaikadu, Pallam, and Puthenthurai coastal zones are highly vulnerable to erosion and land submergence resulting from high-energy waves, tidal actions, and other extreme events. Overall observation reveals that changes in physical and environmental factors directly influence the growth and productivity of coastal habitats in the wetlands, lagoons, estuaries, sea-grass beds, coral reefs, mangroves, and dunes vegetative cover. Anthropogenic influence seriously deteriorates the life cycle of the marine and coastal ecosystem in the nearshore environment producing adverse impacts on a long-term scale. Mapping of coastal habitat vulnerability using GIS based HVI model provides crucial information for long-term sustainable coastal habitat management.