ANALYSIS OF MODELING RESULTS FOR RIVER BANK PROTECTION OF THE MOST VULNERABLE PART OF TAZUMUDDIN UPAZILA UNDER BHOLA DISTRICT

Abstract

Bhola is the largest Island of Bangladesh situated in the south central region (latitude approximately from 430000N to 525000N and longitude 555000E to 590000E) of Bangladesh in the highly dynamic Meghna Estuary. In recent years the erosion along eastern shoreline of Bhola Island has become a serious issue. Attempts are taken to establish the base line condition to simulate the natural phenomena. Baseline condition for Tazumuddin Upazilla (under Bhola district) has been developed based on hydrodynamic and morphological modelling and historical data of bank line shifting, thalweg line shifting, bathymetric data, char movement etc. To calibrate and validate the model water levels and discharge are successfully calibrated. From modeling result, erosion/deposition pattern at and outside the protective works, new vulnerable areas due to revetment have been identified. Hydrodynamic (HD) simulations during ebb tide the maximum depth integrated near bank velocity is found within the range of 1.5-3.0 m/s along the riverbank of Tazumuddin and 1.0-1.5 m/s along the riverbank of Lalmohan. Morphological simulation shows the channel is further extended towards the south-east part. Further computational simulation showed that channel in front of Tazumuddin become deeper and it is extended more towards the south-east direction. From bathymetry survey data in May, 05 it is found that there is a tendency to deepen the channel in front of Tazumuddin where protective work was suggested and the deep channel is further extended towards south-east direction like simulation result. So it can be concluded that simulation result and real condition near Tazumuddin follows the same trend of channel development.