Morphological changes and vegetation index variation along the western coastal zone of Bangladesh
| Main Authors: | Shibly, A.Md., Takekawa, S. |
|---|---|
| Format: | Article |
| Bahasa: | eng |
| Terbitan: |
Hasanuddin University Press
, 2013
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| Subjects: | |
| Online Access: |
http://repository.unhas.ac.id/handle/123456789/7524 |
Daftar Isi:
- Being a low laying deltaic country, morphological changes along the Bangladesh coastal zones are of major socio-economic and environmental concern. In this study, images of LANDSAT captured during 1989-2010 are analyzed to detect the variation of shoreline positions. Western coast has been divided into different segments and the rates of change of shoreline positions have been analyzed over three time periods 1989-2000, 2000-2006 and 2006-2010. AVHRR GIMMS and MODIS NDVI (Normalized Difference Vegetation Index) data sets are adopted during 1985-2006 and 2005-2010 respectively to monitor the long term variation of NDVI for the segments covered with mangroves. Fourier analysis has been performed to extract primary variation from NDVI time series. River discharge, water- and soil- salinity and wave hind cast (ECMWF) data has been also considered to infer the mechanism of shoreline dynamics and changes of NDVI variations. Every segment underwent rapid erosive changes during the periods of 1989-2000 and 2006-2010, compared to the period of 2000-2006, further segments covered with mangroves changed more rapidly than flat sandy beaches, contradicting the general consensus that mangrove stabilizes the land. Variation of NDVI showed a decreasing trend during the period of 1995-2000 and 2005-2010 at most of the locations, which may an indication of the decreasing tendency of vegetation activity of the area. Oppositely during the periods of 2000-2005, NDVI was in an increasing trend at all locations. Due to the construction of upstream barrage, fresh water discharge through the adjacent rivers decreased and water- and soil- salinity increased around the mangrove forest in the earlier period. This may impact mangrove ecosystem and accelerated the erosion. Shoreline of the western side of every segment faced larger changes compared to east side, which may be due to prevailing waves from south-south-west and consequent sediment transport from west to east.