Brahmaputra River Bank Erosion as a Major Geo-Environmental Problem in Lower Assam, India

Abstract

Abstract The concepts as well as the methodological approaches for investigating geo-environmental pattern, process and problems in a region have been continuously getting their holds since few decades past to make them firm-footed in the contemporary trend of geo-environmental studies. The lower Brahmaputra River valley of Assam, like other parts of northeast India, stands amidst complex geotectonic and physiographic set-up because, of its hills, foothills and river plain topography. The state of Assam as a whole, eventually have been experiencing natural hazards like floods including flash floods, river bank erosion, landslide, etc. Out of which bank erosion heavily affects on the life and land properties of the peoples in affected area by completely damaging it. The river Brahmaputra has a tendency to shifting southward due to various geo-tectonic and seismic instabilities of the region. It is found that during the last 50 years nearly 100 sq km of the study area is eroded in the southern part of the district of Goalpara only. The intensity of shifting is very high mostly in the lower Brahmaputra valley including western margin of the districts of Goalpara, South Salmara Mankachar and Dhubri. The data derived from 14 cross sections along the selected points of lower Brahmaputra reveals that the average annual southward shifting of the river due to bank erosion is 109.14 m/year. Hence, bank erosion has been a serious problem, which is caused mainly by the seismic instability, stream bed rise-up, continuous sedimentation; Intense rainfall, etc. And eventually the phenomenon results into the loss of large tracts of fertile agricultural lands on both the banks of the river Brahmaputra in the study area. The present paper is an attempt to analyze the cause and consequences of Brahmaputra River Bank Erosion as a major geo-environmental problem with special reference to the bank line at Goalpara district of lower Assam in India.