Wednesday, August 12, 2015

Assessment Of India Coastal Erosion

Some data points on changes in India's coastline due to erosion and accretion over 15 years (1989-91 to 2004-2006)

Assessment of coastal erosion along the Indian coast on 1 : 25,000 scale using satellite data of 1989–1991 and 2004–2006 time frames 

The  long  stretch  of  coastline  on  either  side  of the Indian  peninsula  is  subjected  to  varied  coastal  processes  and  anthropogenic  pressures,  which  makes  the coast vulnerable to erosion. There is no systematic inventory  of  shoreline  changes  occurring  along  the  entire  Indian coast  on 1:25,000  scale, which is required for  planning  measures  to  be  taken  up  for  protecting the coast at the national level. It is in this context that shoreline  change  mapping  on  1:25,000  scale  for  the entire Indian coast based on multi-date satellite data in GIS  environment  has  been  carried  out  for  1989–1991 and  2004–2006  time  frame.  The present  communication discusses  salient  observations  and  results  from  the shoreline   change inventory.   The   results   show   that 3829 km (45.5%) of the coast is under erosion, 3004 km (35.7%)  is  getting accreted, while  1581 km (18.8%)  of the coast is more or less stable in nature. Highest percentage  of  shoreline  under  erosion  is  in the Nicobar Islands (88.7), while the percentage of accreting coastline  is  highest for  Tamil  Nadu  (62.3)  and Goa  has the highest   percentage   of   stable   shoreline   (52.4).   The analysis shows that the Indian coast has lost a net area of  about  73  during  1989-1991  and  2004–2006 time  frame.   In Tamil Nadu,   a   net  area   of  about 25.45 has increased due to accretion, while along the Nicobar Islands  about  93.95 sq. km  is  lost  due  to erosion.  The  inventory  has  been  used  to  prepare a Shoreline Change Atlas of the Indian Coast.

Background geological processes keep reshaping coastlines, but this short time frame assessment seems to have captured several anthropogenic disturbances. And one big natural event- the 2004 Indian Ocean tsunami appears to have caused considerable erosion in the Andaman and Nicobar Islands.

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