Application of Remote Sensing and GIS in studying changing river course in Bankura District, West Bengal

Remote Sensing and Geographical Information System has emerged as the most important tool of a geographer to handle spatial data. This technique is now widely used around the world to analyse physical as well as cultural geographical elements. Change in the alignment and course of streams is one such area where such a sophisticated technique can be applied fruitfully, the results of which are utilized in several regional planning occasions. Drainage system of an area is a dynamic system of the earth which always keep on changing in response to the changes in the earth-atmosphere system. The present study deals with the changes occurred in the drainage system of Bankura district- its morphology and alignment as well as its adjustment with underlying structure. Bankura district is the connecting link between the western upland and eastern alluvial tract of West Bengal. The district is located between 22° 38’N and 23° 38’N latitude and between 86° 36’E and 87° 46’E longitude, covering an area of about 6882 sq. Km (DSH, Bankura, 2006). This isosceles triangle look district is geologically a portion of eastern extension of Chhotanagpur plateau. Thus it has a very long geological history. Consequently, the evolution of drainage in this area has passed through long period of denudation. Rivers always undergone through change in its shapes and alignment by continuous changing their hydrodynamic and morphodynamic processes, depending upon the slope, terrain characteristics, structural parameters, vegetal cover with due course of time. For the present study, topographical maps, satellite images (MSS and ETM+) of different dates and the google earth image of 2011 are analysed using RS-GIS softwares. The results obtained from these analyses are then overlaid one upon another and the change in alignment of each course is determined on the basis of various channel morphological parameters such as sinuosity index, cross valley asymmetry, meander ratio, entrenchment ratio and other morphological characters.