Seasonal Variation of Water Qualities in River, Lake and Waterfall in Rangamati and Khagrachhari Hill Tracts, Bangladesh

This study was conducted to investigate the seasonal variation of water qualities for drinking and conservation of aquatic organisms from river, lake and waterfalls in Chattogram Hill Tracts of Bangladesh during pre-monsoon, monsoon and post-monsoon seasons from the period of March 2021 to February 2022. Water samples were collected from four sampling locations and analysed in the research laboratory of the Department of Environmental Science and Resource Management, Mawlana Bhashani Science and Technology University. Results were recorded on the parameters like temperature, EC, TDS, DO, BOD, pH, total alkalinity and total hardness in Kaptai Lake, Chengi River, and Shuvolong and Risang Waterfalls. The study revealed that the temperature, EC, TDS, BOD and pH were higher in pre-monsoon than monsoon followed by post-monsoon seasons. On the other hand, total alkalinity and total hardness were higher in post-monsoon than monsoon followed by pre-monsoon seasons. In the waterfalls, DO was higher in monsoon season when compared to pre-monsoon and post-monsoon seasons. The study provides baseline data on physiochemical water qualities in lake, river and waterfalls at the Chattogram Hill Tracts, which contributes to the long-term conservation of those aquatic ecosystems for human consumption and fisheries management.