Evaluating bank erosion and identifying possible anthropogenic causative factors of Kirtankhola River in Barishal, Bangladesh: an integrated GIS and Remote Sensing approaches

Abstract

In Bangladesh, riverbank erosion has turned into one of the most frequently occurring natural disasters, and it affects the socio-economic and livelihood status as well as the environment of the adjoining areas. Kirtankhola River in Barishal, is this kind of river. This study assesses the amount of erosion-accretion, examines river profile, detecting key anthropogenic factors behind it, and signifying channel shifting of the river within 10 years (from 2009 to 2019). The study used Landsat Satellite imageries, geospatial techniques, and a semi-structured questionnaire survey throughout the study area. The study showed that erosion dominants at the left bank of river (17.1 ha/year), whereas the accretion rate is higher at the right (19.72 ha/year). Besides, cross-section at selected points of the river providing an evident indication of the river widening thus river course shifting. According to 61% of the participants in the questionnaire, high waves generated through water vehicles are the main culprit for this extensive erosion. The number of launches has increased significantly within the studied time-period, and most of the launches run over 30 km/h velocity, where it should be less than 20km/h. The study explored a mechanism of how centrifugal force produced by water vehicles increases the intensity of riverbank erosion in the meandering area.