A proposed method of bank erosion vulnerability zonation and its application on the River Haora, Tripura, India

Abstract

In this paper a new RS-GIS based simple method has been proposed for estimating bank erosion. This method does not need intense field investigation and can provide erosion vulnerability zonation for the entire river. The method uses eight parameters, i.e., rainfall erosivity, lithological factor, bank slope, meander index, river gradient, soil erosivity, vegetation cover, and anthropogenic impact. Meteorological data, GSI maps, SRTM DEM (30-m horizontal resolution), LISS III (23.5-m resolution), and Google Images have been used to determine rain erosivity, lithological impact, bank slope, meander index, river gradient, vegetation cover, and anthropogenic activities. Soil map of the NBSSLP (National Bureau of Soil Survey and Land-use Planning, India) has been used for assessing soil erosivity index.By integrating the individual values of those six parameters out of those eight parameters (the first two parameters remained constant for the particular study area), a bank erosion vulnerability zonation map of the River Haora, Tripura, India (23°37′–23°53′ N. and 91°15′–91°37′ E.) has been prepared. The values have been compared with the existing BEHI-NBS method of 60 spots and also with field data of 30 cross sections (covering the 60 spots) taken along a 51-km stretch of the river within Indian Territory, and we found that the estimated values are matching with the existing method as well as with field data. The whole stretch has been divided into five hazard zones, i.e. very high, high, moderate, low and very low hazard zones; and they are cover 5.66, 16.81, 40.82, 29.67, and 9.04km, respectively.