5TH International Congress on Technology - Engineering & Science - Kuala Lumpur - Malaysia (2018-02-01)

Applicability Of Landsat Tm And Modis Images For Soil Salinity Mapping Of Coastal Bangladesh

Soil Salinity is one of the major influential factors of crop production, which has become the prevalent hazard to land degradation in the coastal areas of Arid and Semi-arid regions [1,2]. Coastal area of Bangladesh is one of the most vulnerable coasts due to natural hazards and human activities also exacerbate the condition. Frequent storm surges and floods due to cyclones and poor agricultural management practices cause the soil salinity in the coastal Bangladesh, resulting the reduction of soil productivity and consequently limiting the crop yield [3-8]. Being a developing country, it is not economic for Bangladesh to monitor and map the saline affected areas and to keep the track of change by conventional methods (e.g. collecting soil samples and testing it in laboratory to measure Electrical Conductivity) [2]. To make this more economic and efficient, applicability of remote sensing images should be the major concern. Numerous researchers have studied the applicability of several remote sensing indices to map saline affected areas of arid regions [2,3,9,10]. But there are very few studies that have focused on the coastal area of Bangladesh. So this study has aimed to evaluate the applicability of Landsat TM and MODIS satellite images to map the saline affected soils of coastal Bangladesh, targeting Barisal Sadar Upazila and Kalapara Upazila as study area (Figure 1). Landsat TM image (path/row: 137/44 and 137/45) dated 23 February 2007 and MODIS Land Surface reflectance image dated 14 March 2007 have been collected from USGS website and used after necessary corrections. Nine different salinity indices including NDVI, SAVI, VSSI and NDSI have been calculated from the corrected bands of satellite images. Soil salinity data collected from Soil Resource Development Institute (SRDI) have been used to find the correlation among the indices and field salinity data. SRDI had collected these samples during February to March of 2007. 93 samples from Barisal Sadar and 85 samples from Kalapara Upazila have been selected for this correlation study. The study revealed a very weak correlation among the indices and field salinity value. Both Landsat TM images and MODIS data have shown similar result. All the indices have shown very low r2 value (within 0.05), which indicate that these satellite images and these indices are not suited to map the soil salinity of coastal Bangladesh. More studies should focus on this topic to find the best-suited remote sensing techniques for soil salinity mapping of coastal Bangladesh.
Jannatul Ferdous, M Tauhid Ur Rahman