Assessment of River Bank Erosion and Vulnerability of Embankment to Breaching: A RS and GIS Based Study in Subansiri River in Assam, India

Abstract

Temporal Satellite Remote Sensing data of a river system of highly unstable bank can be analyzed in GIS environment for identification of river bank erosion as well as patches of embankment vulnerable to breaching. A case study was carried out in the Subansiri River, a tributary of river Brahmaputra of Assam, in India to identify locations of bank erosion and corresponding patches of embankment vulnerable to breaching. Temporal dataset of cartosat-1 imagery for the year 2007 and 2009 were used for mapping the flow channel of river Subansiri. Embankments present in the river were mapped from the cartosat-1 data with the help of embankment index map collected from Assam State Water Resource Department. Based on the degree of convergence and narrowness between the flow channel and embankment, some patches of embankment identified as vulnerable to breaching and classified as very high, high and moderate vulnerable to breaching. Three patches of embankment were identified as very high vulnerable to breaching which came to be true in successive flood season of 2010. The method may be a good tool for predicting embankment vulnerability to breaching due to bank erosion and can be implemented for planning of river bank protection work and preparedness for flood season for a flood prone state like Assam.