HYDRODYNAMIC AND MORPHOLOGICAL STUDY OF PADMA RIVER USING DELFT 3D

Abstract

Due to the tendency for erosion and deposition, the Padma, which was once thought to be a mostly meandering stream, is now transitioning into a braided system. In order to determine the Padma River's optimal hydrodynamic and morphological behavior, it is necessary to do morphological analysis. In the process of this research, a two-dimensional model of the river Padma was constructed with the help of Delft3D for the purposes of analyzing the hydrodynamic and morphological behavior of the Padma River in Naria Upazila. The data on water level, discharge, sediment and bathymetry are gathered from BWDB. Time series discharge data is utilized as the upstream boundary and water level data as the downstream boundary for hydrodynamic and morphological computation. The model is simulated for the monsoon season of the year 2021 with Bilaspur Bazar as the upper-southern boundary and Islampur functioning as the lowersouthern boundary. The accuracy of the model is calibrated by comparing it to the water level that was actually present at Mawa in June of 2021. After the calibration process is complete, the model is evaluated at the same location during the months of September of the following year (2021). Once they have been calibrated and validated, the variation of hydrodynamic properties is investigated, including changes in velocity and discharge as well as variations in water level. Then, the morphological characteristics, such as the rate of sediment transport and cumulative erosion/deposition at vulnerable sections, are evaluated. Results show that in September, the velocity is observed to be at its highest around the river's lower middle and narrow parts. It is observed that the velocity of the river and the rate of sediment movement are highly correlated. When the critical high discharge and water level were used, the velocity was greater than the unsteady model simulation, where the monsoon data of 2021 was used. So, the erosion and deposition was greater for steady case