Evaluation of water quantity–quality, floodplain landuse, and land surface temperature (LST) of Turag River in Bangladesh: an integrated approach of geospatial, field, and laboratory analyses

Abstract

Rapid urbanization, industrialization, and development activities are posing numerous threats to the rivers of Bangladesh. In the recent decade, Turag River has been exposed to severe threats due to anthropogenic activities. The present research deals with the evaluation of water quantity–quality, landuse and landcover (LULC), and land surface temperature (LST) of Turag River and its floodplain by using an integrated approach of field study, laboratory analysis, and geospatial techniques. LULC mapping of the study area has been done using multi-temporal Landsat satellite images by unsupervised method, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index indices (NDWI) approach. From LULC classification, the study shows that the average reduction of water bodies from 1989 to 2019 is about 60–66%, and the rate of reduction is about 14.25 ha per year. Due to anthropogenic activities and rapid urbanization, a large number of water bodies have been depleting. The average temperature of the river water from filed observed data is 30.23 °C and from image processed data is about 28.32 °C. The minimum and maximum values of pH, EC, TDS, and Eh are 6.87–8.44, 808–1192 μs/cm, 406–739 ppm, − 31 to – 150 mV, respectively. The concentration ranges of cations (Na, Ca, Mg, K, Fe, and Mn) are 85.43–247.60, 28.59–39.47, 11.1–13.58, 5.21–13.26l, .07–1.14, .006–.47 mg/l consecutively. The ranges of anions concentration (HCO3−, Cl−, SO42−, NO3−) are 165.45–388.87, 54.81–194.07, 52.49–289.63, l9.63–126.93 mg/l, respectively. It is evident that HCO3−, NO3−, and Mn exceed the standard limit of Bangladesh Water Quality Standard (BWQS) and World Health Organization (WHO), indicating that the water of the Turag River is deteriorating that is not safe for human consumption and aquaculture purposes. The study will assist to take some effective measures to control the pollution and uphold the water quality and natural riparian processes. So, the outputs of the study will contribute to the future urban landuse planning in the river floodplain area to mitigate ongoing alarming pollution and unplanned industrialization.

Causes and Consequences of River Pollution: An Exploratory Study Along the Turag River Area, Tongi, Bangladesh

“…The respondents (12.9%) also recognized the use of river water in industries to operate machinery and cool it down as one of the most important causes of river pollution, as this nasty water, which includes chemical composition, is subsequently discharged back into the river (Observation; Photograph 1b) ended up with increasing river water temperature. The work of Tania et al (2021) confirmed that the excessive temperature of river surface water was due to the discharge of hot wastewater from industrial sources besides the Turag River. The respondents considered this factor as another cause of river pollution as the water used for cooling is warmer than the river water at normal temperature.…”

“…Multi-spectral satellite data has identified rapid conversion from agricultural cultivated land to urban land uses along the Turag-Tongi basin over the last few decades (Dewan et al, 2012;Dewan and Yamaguchi, 2009). However, the study by Tania et al, 2021;Hassan et al, 2019;Zaman et al, 2018;Saha et al, 2016;Guttikunda et al, 2013, etc. confirmed that local land uses are correlated with the deterioration of Turag River water quality.…”

Spatial Assessment of Post COVID Water Quality Status of Turag River for Sustainable Water Resource Management in Bangladesh

“…The area in which this research work was conducted is also known as "Tongi Heavy Industrial Area". For the last few decades there has been incredible industrial influx and development near the periphery of the Turag River and thus due to immense discharge of industrial effluents the water quality of this river has been severely degraded [28]. The Turag River has been avowed as one of the "Ecologically Critical Areas (ECA)" of this country by the Department of Environment Bangladesh [29].…”

“…In addition, insufficient monitoring and law enforcement by government officials were recorded in textile companies. Prioritize the execution of the existing laws and effective governance including all stakeholders in order to ensure improved water sources for all[28,15]. It is necessary to ensure the prevention of illegal encroachment, the marking of river channel borders, and the dredging of severely narrow and shallow riverbeds.…”

Study the Relationship Between LULC, LST, NDVI, NDWI and NDBI in Greater Arba Minch Area, Rift Valley, Ethiopia

“…By providing timely and synoptic views of land-based coverage, remote sensing images more suitable for monitor NDVI, NDWI, and NDBI [19], [20], [21], [22]. types and times [23], [24], [25], [26], [27], [28] [29], [30], [31], [32]. There are various methods for measuring the LST by using field measurements, but that's very complex and expensive.…”