Evaluation of vegetal cover loss and its impact on surface temperature in Manipur valley using remote sensing and GIS technology, India

Abstract

This study assesses forest cover change (1989–2016) in the Manipur valley using Landsat imageries and examines the quantum change in land surface temperature within the study area. Vegetation abundance is one of the most influential factors in controlling Land surface temperature. Vegetation change, NDVI and LST maps of four different dates are generated using Landsat TM images for 1989, 2002, 2009 and Landsat 8 OLI for 2016. Limited ground truth verification and field visits were conducted. The study reveals that the forests area decreased at an average annual rate of 330 ha year-1, amounting to a rate of loss of 8.6 % year-1 whereas the built-up area increases by 4 fold and the surface temperature simultaneously increases spatially over the study periods. The initial findings have shown that there is significant increase in the built-up areas, the conversion of forest cover into residential and commercial areas resulted in higher LST in impervious areas. Dense forest and water bodies comparatively observe low temperature than the built-up land. The study evaluates the relationship between the land surface temperature and vegetation cover loss, using Normalized vegetation index (NDVI) to indicate vegetation abundance. A strong negative correlation results between LST and NDVI, where the cooling effect of green areas can be observe. The results indicate a greater loss of the natural ecosystem to infrastructural development at the expense of forest class.