Application of 2D Modeling for Design of Anti Erosion Works for a Braided River - A Case Study

Abstract

River bank erosion is inevitable part of natural geological cycle. However, the erosion results in loss of land, damage to the properties, communication systems, etc. River bank erosion is a process of detachment of soil particles due different causes, like high velocity flows, obliquity of flow, undermining, piping, sloughing etc on one hand and poor engineering properties of soil on the other hand. The braided rivers are naturally unstable, causing frequent bank erosion in different reaches and at varying rate. If the bank is composed of finer non-cohesive material, the erosive activity could take serious turn. Therefore, arresting the erosive activity is given high importance. Anti-erosion works are normally costly. Therefore, such measures are executed mainly at critical locations. For providing dependable protection, scientific approach is required for design. Hence, selection of suitable hydraulic design parameters is of prime importance. Numbers of methods are available to determine the hydraulic design parameters. In this paper, the application of 2D mathematical modeling for deriving hydraulic parameters is presented. Considering the braided pattern and being an alluvial river, 2D modeling was felt absolutely necessary for true representation of the flow conditions and velocity distribution in such a river. After studying alternative methods for the anti erosion works, protection works in the form of revetment and launching apron using Geobags/ stones laid over Geo-synthetic filter was finalised.