Pa ge 1 Pa ge 35 American Journal of Environment and Climate (AJEC) Surface Water Quality Assessment in the Different Coastal Regions of Bangladesh Rubinoor Islam1*, Maisha Maliyat Aronna2, Md. Abdullah Al Arafat1, Md. Zakir Hossain1 Volume 4 Issue 3, Year 2025 ISSN: 2832-403X (Online) DOI: https://doi.org/10.54536/ajec.v4i3.4435 https://journals.e-palli.com/home/index.php/ajec Article Information ABSTRACT Received: May 22, 2025 Accepted: June 30, 2025 Published: September 11, 2025 The study evaluated the suitability of surface water for routine utilization in the coastal regions of Bangladesh during the period from February to May 2023. Water samples were collected at 11 sampling stations near the river in 7 distinct districts and analyzed at NGO Forun in Dhaka using Standard APHA methods. The results indicated that the pH, TSS, DO, nitrate, and BOD readings were within acceptable limits according to WHO’11 standards. The TDS, chloride, hardness, and EC values at all sites exceeded the allowable range. The TDS and EC values were 25,300 mg/L and 50,570 µs/cm at Kutubdia, while chloride and hardness were 5,984 mg/L and 9,810 mg/L at Bhatiary, which were the highest values among all stations. The minimum values recorded for TDS, chloride, hardness, and EC were 330 mg/L, below 60 mg/L, 90 mg/L, and 645 µs/cm, respectively. GIS was used to understand the scenario of acceptability of surface water in the coastal region. The correlation analysis revealed a high positive correlation between the EC value and the hardness, chloride, BOD, and TDS readings. Surface water EC values may increase due to saline intrusion caused by rising sea levels, decreased upstream flow, natural disasters, and increased groundwater exploitation. Keywords Coastal Regions, Electrical Conductivity and WHO’11, GIS, Water Quality 1 Department of Civil Engineering, European University of Bangladesh, Dhaka-1215, Bangladesh 2 Environmental Engineer, Imam and Associates, Mirpur-06, Dhaka-1216, Bangladesh * Corresponding author’s e-mail: rubinoor@eub.edu.bd INTRODUCTION Safe and accessible water is essential for the existence of life on Earth. Potable water can enhance the environment, health status, economy, and food production (Jain, 2011). Approximately 36% of individuals residing in urban areas and 65% living in rural areas did not have access to potable water (Sharma & Mishra, 2022). One of the most significant challenges in contemporary global development is guaranteeing sustainable water security (Srivastava et al., 2022). By 2021, the number of individuals residing in water-stressed nations has surpassed 2 billion. This predicament is projected to worsen in specific areas due to the combined effects of climate change and population expansion (Marzi et al., 2021). The ecological and socio-economic significance of marine ecosystems is crucial for both wildlife and human populations, with their benefits being contingent upon maintaining high water quality (Suarez et al., 2024). The Coastal zones of Bangladesh are characterized by their hydrological nature, since they are included by the Ganges, Brahmaputra, and Meghna (GBM) river system, as well as the Bay of Bengal. The coastline region encompasses 32% of the country’s total land (Ahamed et al., 2020). Most of Bangladesh’s coastal towns are situated along the shores of low-lying tidal zones, with an average elevation of 1.0– 1.5 meters above sea level (Rahman & Rahman, 2015). The coastal population of Bangladesh in these regions heavily depends on rivers, tube wells (groundwater), and ponds for the purposes of washing, bathing, and obtaining drinking water (Habiba et al., 2013; Abedin et al., 2018; Khan & Paul, 2023). The circular and aqueous environment of the southwestern coastal regions of Bangladesh, known as SWCRB, is highly vulnerable to the infiltration of saltwater caused by cyclones and storm surges (Raknuzzaman et al., 2016; Ashrafuzzaman et al., 2022). The overall saline area has expanded to around 1.056 million hectares, up from 0.833 million hectares during the past four decades (Hasan et al., 2019). The salinity intrusion in the coastal zone of Bangladesh is caused by several factors, including the country’s critical geographical location, reduced river flow due to a barrage in the upstream neighboring country, inadequate management of coastal polders, rising sea levels, cyclones and storm surges, backwater effects, precipitation, and shrimp culture (Ayers et al., 2017; Islam et al., 2017). Water quality is often categorized based on biological, physical, and chemical criteria, with multiple factors falling under each category (Akhtar et al., 2020). The physicochemical and biological characteristics of the aquatic environment directly influence the organisms inhabiting these water bodies and the overall aquatic ecosystem (Ebuete et al., 2023). So, the assessment of these three categories, utilizing parameters obtained by on-site monitoring of water samples, offers crucial data for discerning patterns, expanding the scope of understanding for water resource authorities, and making recommendations for future planning (Sutadian et al., 2016; Zainurin et al., 2022; Amon et al., 2022; Hassan et al., 2020). Multiple research studies have tested the water quality of the coastal zone in Bangladesh. The investigations have concentrated on groundwater hydro geochemical characterization, suitability for irrigation and drinking purposes, and the effects of shrimp farming and toxic algal blooms. The findings imply that water quality in the coastal region of Bangladesh differs based on the location and Pa ge 36 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(3) 35-42, 2025 characteristics examined. Some regions have groundwater that is potable and good for drinking and irrigation, while others are deemed unsuitable for human consumption. Shrimp farming operations have been identified as a possible source of water quality problems, including elevated ammonia and nitrogen levels. Harmful algal blooms have been seen in coastal waters, impacting aquatic ecosystems, fisheries, and public health. Additional study is required to enhance our comprehension and reduce the negative impacts of these blooms on the marine resources in the Bay of Bengal (Shaibur et al., 2023; Khan et al., 2022; Tajwar et al., 2023; Uddin et al., 2024; Hossain al., 2021; Akhter et al., 2023; Hossain., 2022). This study evaluated the geochemical features of surface water (SW) in the coastal region. The primary objective of this study was to assess if the water quality at the research locations is suitable for routine purposes. To accomplish this, the study had the following objectives: generating maps of the region using GIS, examining surface water’s parameters and co relation between them. MATERIALS AND METHODS Study Area According to Adhikary et al. (2012), Bangladesh has a 711-kilometer coastline that includes a vast system of river canals. In ten districts, including Chattogram, Cox’s Bazar, Khulna, Bagerhat, Satkhira, Barisal, Patuakhali, Laxmipur, and Bhola, the study was carried out in eleven villages and three upazilas (sub-districts) (Figure 01). Due to the restricted water supply, salinity, and other water quality criteria, certain coastal regions of the nation are having a very difficult time meeting their freshwater demands (Adhikary et al., 2012M. R. Khan et al., 2022). As shown in Table 1 below, samples are taken following the usual procedure for gathering water samples from a variety of districts and locations. Sampling Water sampling was conducted from February to May 2023, both during dry and pre-monsoonal months to control for temporal differences in water quality. Triplicate samples were collected at each of the 11 stations to reduce temporal sampling bias. Samples were collected using pre- cleaned 1000ml high-density polyethylene (HDPE) bottles, following standard APHA guidelines. The bottles were rinsed with sample water three times before collecting. Each sample was preserved immediately by storing it in a light-restricted icebox and transported to the laboratory within 12 hours to minimize degradation. Table 1: Sampling collection points from different locations to the related rivers Location Surface Water Collection Date Lat-Long Kokilmoni Java River 20 Feb 2023 21.946128° - 89.597579° Dobeki Araibegi River 22 Feb 2023 22.098412° - 89.228009 Char Manika Meghna River 2 April 2023 22.015178° - 90.664761° Koyra Sakbaria River 4 April 2023 22.210402° - 89.325218° Kutubdia Kutubdia Channel 22 Feb 2023 21.814728° - 91.869565° Nizampur Meghna River 2 April 2023 21.894699° - 90.137158° Nolian Shibdah River 11 April 2023 22.460082° - 89.436424° Ramgoti Meghna River 23 March 2023 22.678353° - 90.910816° Figure 1: The overall scenario of the study area in Bangladesh Pa ge 37 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(3) 35-42, 2025 Shoronkhola Panguchi River 30 March 2023 22.472419° - 89.860601° Bhatiyari Bay of Bengal 27 March 2023 22.511468° - 91.700591° Tojumuddin Meghna River 22 Feb 2023 22.414012° - 90.851517° Parameters and Analytical Method All tests were performed at NGO Forum, Lalmatia, Dhaka. Instruments for measuring physicochemical parameters (EC meters, DO meters, Spectrophotometers) were calibrated using standard solutions. The Table 2 shown below summarized the physicochemical parameters analyzed in this study, along with the respective analytical methods and standard protocols followed. Table 2: Analytical Methods for Water Quality Parameters Parameter Analytical Method Standard Protocol pH Digital pH Meter APHA 4500-H⁺ Total Dissolved Solids (TDS) Digital Conductivity/TDS Meter APHA 2540C Dissolved Oxygen (DO) Winkler Titration Method APHA 4500-O Nitrate (NO₃⁻) UV Spectrophotometry APHA 4500-NO₃ E Chloride (Cl⁻) Argentometric Titration APHA 4500-Cl⁻ B Total Suspended Solids (TSS) Gravimetric Analysis APHA 2540D Biochemical Oxygen Demand (BOD₅) 5-Day Incubation at 20°C APHA 5210B Electrical Conductivity (EC) Digital Conductivity Meter APHA 2510 Hardness (as CaCO₃) EDTA Titrimetric Method APHA 2340C RESULTS AND DISCUSSIONS Water Parameters The Surface water quality of the coastal regions of Bangladesh was evaluated by analyzing their physicochemical parameters and comparing them with established standards according to WHO (WHO’11). The pH values of surface water samples in the coastal region range from 7.1 to 7.9. According to WHO’11, these values were within the range of 6.5–8.5. Figure 2: pH concentration: (a) Spatial Distribution using GIS, (b) pH vs Locations. The average TDS value was remarkable high in the Kutubdia Channel, which was 25300 mg/L. In addition, the TDS values for the Meghna River in Ramgoti, Tajumuddin, Char Manika, Nizampur were 6430 mg/L, 2557 mg/L, 330 mg/L, and 7120 mg/L, respectively. On the other hand, the TDS values for the Java River at Kokilmoni, the Araibegi River at Dobeki, the Sakbaria River at Koyra, the Shibdah River at Nolian, the Panguchi River at Shoronkhola, and the Bay of Bengal at Bhatiyari were 13,160 mg/L, 13260 mg/L, 23000 mg/L, 3250 mg/L, 5840 mg/L, and 24000 mg/L respectively. According to WHO’10. The TDS readings for all surface waters, except Char Manika, were higher than the standard. The TSS value for all locations was within permissible limits. Pa ge 38 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(3) 35-42, 2025 The dissolved oxygen for all samples was within standard limits. The average value was the minimum for Jamuna River at Ramgoti, which was 5.5 mg/L, and maximum was 6.1 mg/L at Char Manika. The nitrate value was maximum for the Meghna River at Char Manika which was 2.3 mg/l and maximum was 15.5 mg/L at Tojumuddin for the same river. All values for other river water were within the standard limit according to standards. The value of chloride in every river’s surface water was higher than the recommended level, except for the Char Manika, which is less than 60 mg/l. The peak value was found at Bhatiary. At Bhatiary on the Bay of Bengal, the hardness and EC values are maximum, whereas at Char Manika, they are lowest. Others were found to be above the standard permissible limit. All BOD values, except for Tojumuddin and Nolian, were within the allowable range. These two stations had the same BOD result of 0.4 mg/L. Figure 3: TDS concentration: (a) Spatial Distribution using GIS, (b) TDS vs Locations. Figure 4: DO concentration: (a) Spatial Distribution using GIS, (b) DO vs Locations. Pa ge 39 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(3) 35-42, 2025 Figure 5: Nitrate concentration: (a) Spatial Distribution using GIS, (b) Nitrate vs Locations. Figure 6: Chloride concentration: (a) Spatial Distribution using GIS, (b) Chloride vs Locations. Figure 7: Hardness concentration: (a) Spatial Distribution using GIS, (b) Hardness vs Locations. Pa ge 40 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(3) 35-42, 2025 Correlation with All Parameters The co-relation matrix (Table 4) shows that conductivity is significantly linked with hardness, TDS, and chloride, negatively with BOD, moderately with pH, and poorly with nitrate and TSS. TDS, chloride, and hardness negatively affect pH. In addition to conductivity, Hardness is negatively correlated with pH and BOD and strongly positively correlated with link with TDS and chloride. Nitrate correlates negatively with DO and positively with TSS. Chloride has a negative correlation with BOD and pH and a positive correlation with conductivity, hardness, and TDS. DO is negatively impacted by concentration of nitrate. Figure 8: EC concentration: (a) Spatial Distribution using GIS, (b) EC vs Locations. Figure 9: BOD concentration: (a) Spatial Distribution using GIS, (b) BOD vs Locations Table 3: Correlation among different parameters Conductivity pH BOD Hardness Nitrate TSS Chloride TDS DO Conductivity 1.000 -0.341 -0.845 0.830 -0.246 0.067 0.836 1.000 0.011 pH -0.341 1.000 0.626 -0.505 0.150 -0.048 -0.515 -0.342 0.092 BOD -0.845 0.626 1.000 -0.749 0.182 -0.059 -0.756 -0.845 0.114 Hardness 0.830 -0.505 -0.749 1.000 -0.100 0.307 0.999 0.831 0.018 Nitrate -0.246 0.150 0.182 -0.100 1.000 0.655 -0.115 -0.247 -0.598 TSS 0.067 -0.048 -0.059 0.307 0.655 1.000 0.305 0.066 -0.215 Pa ge 41 https://journals.e-palli.com/home/index.php/ajec Am. J. Environ. Clim. 4(3) 35-42, 2025 CONCLUSIONS From the experimental Data, the pH, DO, and Nitrate were within the acceptable limits according to WHO’11, except for the CharManika, all tested parameters such as TDS, chloride, EC, and Hardness values were high for the surface water. The graph generated by ArcGIS 10.5 presented above displayed fluctuations in the various parameters that were assessed during the study. It helped with the simplification and explanation of all evaluated factors by illustrating the intensity of different parameters within the study area. The high EC value indicated that the water at the chosen sites was saline, posing a greater risk of human indigestion. High Total Dissolved Solids (TDS) levels might lead to odor issues and be aesthetically unsatisfactory. The high value of Hardness might be caused by problems associated with scale formation. From the correlation, it was found that the correlation coefficient values between conductivity and TDS, conductivity and Hardness, and conductivity and chloride ions were positive, showing that TDS, Hardness, and chloride rise as conductivity increased. The increase in conductivity was positively associated with the presence of chloride ions in water. This principle also applied to the relationship between conductivity and Hardness. In conclusion, the surface water in most studied regions is not suitable for routine domestic use without treatment, especially due to high salinity and mineral content. The study also emphasized generally the need of efficient water management techniques to solve salt intrusion, nutrient loading, and other water quality problems in coastal Bangladesh. While the study reiterated the need for legislative measures and integrated management of water resources to counteract salinity impacts, there is a need to understand predominant methodological shortcomings. These included limited seasonal coverage, absence of microbial or heavy metal data, and restricted longitudinal sampling. In addition, while spatial variability was traced well with GIS, hydrodynamic modeling and pollutant source tracing were not conducted. Future studies must incorporate with year-round surveys to assess seasonal dynamics; inclusion of toxicological parameters; hydrological modeling combined with remote sensing; surveys of community perceptions and uses of water. Relevant policy and stakeholder- specific recommendations are: • Setting up coastal buffer zones to reduce saline ingress. • Enforcing wastewater discharge regulations in upstream areas. • Investment in decentralized water treatment to remove saline for high salinity areas. • Regular monitoring for frameworks assisted by the government as well as local institutions. By addressing these areas, future studies can not only build upon the findings of this research but also improve water security and resilience in vulnerable coastal zones of Bangladesh. Acknowledgment The authors would like to thank Imam and Associates for its support REFERENCES Abedin, M. A., Collins, A. E., Habiba, U., & Shaw, R. (2019). 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