12 Feb Coastal Hazards: Are we doing enough?
Dr Thrivikramji KP,
Emeritus Fellow, Dept of Geology,
University of Kerala, Kariavattom Campus 695 581
All across the world, the coastal land is home to mega population centers and scores of smaller cities and towns, which are wide open to and practically defenseless against the most destructive forces of nature like, severe-storm-related hazards, hydrologic floods, beach erosion and tsunamis. Added to this, several coastal communities face massive threats to livability and property primarily contributed by anthropogenic actions, like green house warming induced sea level rise, land subsidence due to mining or withdrawal of fluids from subsurface, pollution of coastal waters, oil spills and sea water ingress into coastal aquifers.
That eleven of the fifteen largest cities of the world are located near the coasts of seas or estuaries is an indicator of the vulnerabilities. In India, state capitals of some littoral states (for e.g., Mumbai of Maharshtra, Panaji of Goa, Trivandrum of Kerala, Chennai of Tamil Nadu and Bhubaneswar of Orissa) are in the coastal land. Conterminous India, with its pretty long shoreline of 5700 km, (Kerala sharing roughly 10%) and being closer to the equator, has its own share of worries arising out of natural hazards. Vulnerability of the population in the coastal land to hazards is directly linked to the morphology of the coastal land (elevation), population density and proximity of population pockets to the shoreline (proximity), or in other words to placing property and lives inappropriate areas.
Human populations, cities, ports, and wetlands in low-lying coastal areas, will be affected by inundation, erosion and salination as a result of a climate change induced sea level rise between 0.3 and 0.9 m say by the end of this century, due to rising greenhouse gas emissions. A chief consequence of SLR is coastal erosion and loss of land and contamination of coastal fresh water aquifers. Consequences of a global sea level rise would be spatially non-uniform because of local or regional vertical crustal “movements”, differential resistance of shoreline to erosion, varying wave climates, and changing long shore currents. Intensive development and investment in the coastal land make them vulnerable at the time of erosion, hydrologic storms, storm surges or tsunamis. `
Vulnerabilities due to Coastal hazards are preventable either by structural interventions or simply by staying away or relocating in the backshore of zones potential threats. While the structures reflect the wave energy, the natural vegetation helps to absorb the same. Options are two sided, like, do nothing and get out of the area or adapt and accommodate. One of the management responses is retreat from the affected area and move toward the backshore. Secondly by building elevated houses on stilts, the affected communities could be saved. Third option is basically preparedness like education and creating awareness and placing early detection, warning and communication and emergency evacuation systems. Preparedness on the part of local and state or national governments in warding off the damages of hazards is fundamental to it.
The recently launched program by the MoEF, GoI for mapping the vulnerable coastal areas of the Indian littoral states and creation of an institute in Chennai for research on coastal hazards are right initiatives. But the state’s contribution in this regard is not yet crystallized fully.
(Abstract of a paper presented in MG University, March, 2011)