Tide driven currents and Nutrient Distribution in the Naf River, Southeastern Coast of Bangladesh Utilizing Coupled Hydrodynamic and Ecological Model

Author: Rayhan Hossain, Md. Kawser Ahmed, Abu Hena Muhammad Yousuf, K M Azam Chowdhury, Rupok Loodh
DOI: doi.org/10.70279/bmj-v8-1031
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A coupled hydrodynamic and ecological configuration was developed using the MIKE 3 model and its Ecolab module to simulate the tide-driven currents, surface elevation, components of the flow and water quality of the Naf estuary, along the southeastern coast of Bangladesh. The present study particularly focuses on the analysis of the local e tidal characteristics and properties of water quality, such as biological oxygen demand (BOD), dissolved oxygen (DO) and nutrients, nitrate and phosphate) within the modeled domain. Water samples were retrieved from six different stations, spanning from (i) the mouth of Naf River, (ii) Shahparir Dwip jetty ghat, (iii) Near Jaliapara, (iv) Sabrang, (v) Teknaf and (vi) Kewari ghat Teknaf. The comparison of Model data with in-situ records showed a satisfactory agreement between the two datasets The highest surface elevation was found at 1.28 m in Kewari ghat and Teknaf because of the narrow area interested by the greatest value of high tide, while the highest current speed was 1.20 m/s in Shahparir Dwip jetty ghat area and lowest 0.0598 m/s in the river upstream area during low tide. Values of BOD close to 1.12 mg/L were found in Teknaf due to sewage and boat waste dumping from the surrounding towns. The DO concentration was as high as 5.89 mg/L in the downstream area. The highest nitrate concentration was equal to 1.58 mg/L in the upstream area of Kewari ghat and the highest phosphate concentration was 1.64 mg/L in the Sabrang area. The water-quality degrading components like nitrate (standard value 0.03-3.0 mg/L) and phosphate (standard value 0.1- 1.0 mg/L) were within acceptable ranges, suggesting that the Naf estuary conditions are suitable for the productivity of aquatic flora, fauna, and for a healthy estuarine environment.