Environmental Challenges 6 (2022) 100423 Contents lists available at ScienceDirect Environmental Challenges journal homepage: www.elsevier.com/locate/envc Eco-environmental assessment of the Turag River in the megacity of Bangladesh Alamgir Kabir ∗ , Hosney Jahan Sraboni , Md. Mahmudul Hasan , Raihan Sorker Department of Environmental Science, Bangladesh University of Professionals, Dhaka 1216, Bangladesh a r t i c l e i n f o Keywords: Turag river Megacity Physicochemical parameters Water quality index (WQI) River Habitat Survey (RHS) a b s t r a c t 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 lo- cations 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 qual- ity 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. 1. Introduction Water is essential for the survival of all living beings on the earth (Rothschild and Mancinelli, 2001). However, a total of 780 million of world’s population are living without access to improved water sources (World Health Organization (WHO) 2014). World’s water security is at risk due to the modification of ecosystem and the discharge of pollutants into the rivers (Kibria, 2016). Within the different sources of water, river water is one of the most influentials to humans because of its multipur- pose uses (domestic, industrial and agricultural) and values (transporta- tion, tourism and recreational) on livelihood (Venkatramanan et al., 2014). Around 187 million people rely on surface water for drinking (World Health Organization (WHO) 2014). The dependency on river water has been increasing with the increasing population, rapid ur- banization and industrialization [(World Health Organization (WHO) 2014; Richey et al., 2015; Dike et al., 2004; Wang et al., 2020)]. The in- creasing global demand for surface water to meet overall human needs will impose immense pressure on the natural resources and ecosystem (World Water Assessment Programme WWAP, 2018). The urbanization process changes the land use-land cover (LULC) pattern and thereby af- ∗ Corresponding author. E-mail address: alamgir.kabir@bup.edu.bd (A. Kabir). fects the water quality and limits the availability of freshwater resources (Zhao et al., 2015; Sun et al., 2013). Water quality deterioration of river is also linked with industrialization as the process often discharges untreated or partially treated effluents into the river (Bansal, 2018; Ebenstein, 2012). Because of the pollution and encroachment of surface water, ensuring sustainable access to clean and safe water for all will be at risk in future (Yogendra and Puttaiah, 2008). In developing coun- tries particularly, providing safe water is becoming challenging as both ground and surface water are becoming contaminated due to the lack of convenient wastewater treatment and drainage facilities (United Na- tions 2010; World Water Assessment Programme (WWAP) 2009). Over 80% of sewage in developing countries is discharged directly into the water bodies without treatment (UN-Water Decade Programme on Ad- vocacy and Communication (UNWDPAC) 2012). The degraded water quality poses threats in achieving UN Sustainable Development Goals (SDGs) in developing countries (United Nations Educational, Scientific and Cultural Organization UNESCO, 2015). About 80% of the conta- gious diseases of the world are associated with unsafe water and around 3.4 million people, predominantly children, die because of waterborne disease every year (Smet and van Wijk, 2002; United Nations Chil- https://doi.org/10.1016/j.envc.2021.100423 Received 2 September 2021; Received in revised form 15 November 2021; Accepted 7 December 2021 2667-0100/© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)