Evaluating the impact of Indian Ocean tsunami on agricultural yield in Hambantota Province, Sri Lanka

摘要

The 2004 Boxing Day tsunami affected the coastal areas in most of the eastern and northern provinces in Sri Lanka, causing widespread damage to house and public infrastructure. In addition, near coastal and low-lying interior coastal regions were inundated by saltwater, many of which were agricultural land. As a result, crops were damaged; agricultural lands were salinised and waterlogged making them unsuitable for cultivation. A number of aid agencies provided subsidised fertilisers to the farmers to recover from this process in a short term; however, the long term effect is still unknown. In this study, remotely sensed data from 2002 to 2006 were used to study the impact of tsunami on agricultural yield. Time series of two vegetation indices (Normalised Difference Vegetation Index and Enhanced Vegetation Index) derived from MODIS data were used. Initial results suggested: (i) an immediate decrease in crop growth in the areas within 6 km from the coast following the tsunami; (ii) increase in yield in these areas in the year following the tsunami and (iii) then a decrease in the yield afterwards. Results from both NDVI and EVI showed the similar pattern in yearly data but EVI was more sensitive to short term changes.