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Environmental Flow Assessment of the Sangu River

Corresponding Author : Aysha Akter (aysha_akter@cuet.ac.bd)

Authors : Aysha Akter (aysha_akter@cuet.ac.bd), Md. Redwoan Toukir , Shifa Mahzabin , Md. Radwan Imroze Khan

Keywords : Flood-prone spots, HEC-RAS, ● Kernel interpolation.

Abstract :

The Meandering Sangu River is well-known for its biodiversity and fish habitat. There are six large Bridges (≥100m in length) and a sluice gate over the Sangu River; thus, flow alteration is apparent. The research question is “What are the impacts of water quality due to high and low flow to the Sangu River?” To answer the research question, the specific objective of this project is to conduct an environmental flow assessment of the Sangu River through two phases of a hydraulic simulation featuring flood events using Hydrologic Engineering Center (HEC) developed River Analysis System (RAS) software. The model simulation was for 2018-2021, with and without assigning hydraulic structures. The calibrated parameter Manning’s n value was obtained at 0.025 by comparing simulated water elevation with an observed water level of Dohazari station collected from BWDB. The simulated water elevation shows a suitable match (i.e., R²=0.87). The HEC-RAS simulated flow was validated with Landsat satellite imagery from USGS and processed by ArcGIS. As the hydrodynamic model fails to simulate low flow conditions, the Indicators of Hydrologic Alteration (IHA) software was applied. Then, the Kernel interpolation method was adopted to simulate water quality parameters. A simulated model was used to validate the physical parameters of this river, and a suitable match was observed. Thus, the resulting map will be helpful for researchers and practitioners in identifying seasonal flood-prone/scarce spots and corresponding water quality to ensure the sustainable biodiversity of this river.

Published on March 28th, 2025 in Volume 5 (Special Issue), Civil Engineering, Environment and Architecture