Effect of Diurnal Tides on the Water Quality Parameters of a Coastal River Connected with the Bay of Bengal

To study water quality changes and tidal effects, hourly samples were collected on 17-18 June 2022, in the Andharmanik River, Bangladesh. Parameters measured included temperature (28.8-30.6 °C), salinity, dissolved oxygen (5.9-6.33 mg/L), pH (7.15-7.98), TDS, conductivity, alkalinity, and hardness. Temperature, DO, and pH showed minimal correlation with water height, while salinity peaked at low tide due to evaporation and no freshwater inflow. Strong correlations were between TDS and conductivity, and water height and several parameters. Most measurements varied with the tide, offering a key baseline data for the region.