Eco-environmental assessment of the Turag River in the megacity of Bangladesh

Abstract

River water quality in rapidly urbanizing Dhaka city threatens to achieve UN Sustainable Goals. Particularly, the Turag River, flowing along the periphery of the Dhaka megacity, is one of the most polluted rivers in the world. The accelerated economic growth based on industrialization, rapid urban expansion and population growth in this megacity pose numerous threats to the health of the Turag River. Therefore, the study aimed to conduct an eco-environmental assessment using Water Quality Index (WQI) and River Habitat Survey (RHS) to determine the physical, chemical and biological status of the Turag River. The study revealed that most of the water quality parameters i.e. pH, electrical conductivity (EC), salinity, total dissolved solids (TDS), major cations and anions were within the national and international (WHO) standards. Turbidity exceeded the desirable limit in all locations whereas, dissolved oxygen (DO) levels in 100% and 30% locations were below the standard for human consumption and sustaining aquatic community respectively. The calculated WQI confirmed that the water quality in most of the locations was poor due to intensive urbanization and industrialization though comparatively good water quality was evident in upstream. Thereby, the study ascertained that the water was not suitable for human consumption. The RHS indicated a poor habitat condition in the Turag River due to human interventions such as intensive channel modification, river encroachment, discharge of municipal and industrial sewage, etc. The findings of our study could be useful to develop urban river management plan to support sustainable river restoration.