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Satellite data based impact assessment of basin characteristics for brahmaputra river system of India
, M.P. Akhtar, B. Zeleke
Published in
Pages: 3792 - 3802
The change of the Brahmaputra basin characteristics has been studied covering around 620km of the River reach in Assam flood plain within Indian Territory. The changes in land use and land cover pattern in the Brahmaputra catchment instigate a significant increase in sediment inflow to the Brahmaputra River System. Land use change may influence many natural phenomena including ecological processes, soil erosion, sedimentation and variations in runoff and soil moisture conditions. Hence, understanding the morpho-dynamic behavior of the river with an extra emphasis on land cover and plan form changes is substantially crucial, so far as impact on the sediment inflow to the river system is concerned. More recently, Sharma and Akhtar (2010) studied the braiding behavior of River Brahmaputra for the discrete years 1990, 1997 and 2007- 08 using remote sensing data based analysis. Their study emphatically suggests a sharp increase in braiding intensities during the aforesaid study period. With above strategy, an objective is set in mind to study in regard to assessment and impact of the land cover changes. Which has been urgently needed for better understanding of the causative factors those influence the braiding pattern, sediment inflow as well as bank erosion phenomena. Hence, for the same discrete years, it is endeavored to study and analyze thebasin characteristics using Landsat (TM) images for the discrete years between 1989 to 2010; covering the catchment area of the River in the three riparian countries (China, India and Bangladesh). NDVI (Normalized Difference Vegetation Index) maps of the study area have been created by considering seasonal vegetation cover changes. Supervised classification was done using MLC (Maximum Likelihood Classifier) to help distinguish between various land cover classes. Change detection algorithm was implemented to determine the changes in vegetation cover in the watershed, floodplain vegetation, vegetated islands, extent and pattern of low flow channels, and exposed sand bars at selected points along the reach. For the same discrete years, a significant change in NDVI values have been registered out of the study, resulting in substantial decrease in vegetation cover and inducing severe channel migration in recent years. Another outcome of the study is that the land cover change in the watershed is not fairly uniform. The landcover change especially, change in vegetation cover surmised to be the vital contributor to the increase in sediment inflow into the Brahmaputra River and its tributaries. © 2011 ASCE.
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