Integrated Approach to Quantify the Impact of Land Use and Land Cover Changes on Water Quality of Surma River, Sylhet, Bangladesh

This study aims to assess the impacts of land use and land cover (LULC) changes on the water quality of the Surma river in Bangladesh. For this, seasonal water quality changes were assessed in comparison to the LULC changes recorded from 2010 to 2019. Obtained results from this study indicated that pH, electrical conductivity (EC), and total dissolved solids (TDS) concentrations were higher during the dry season, while dissolved oxygen (DO), 5-day biological oxygen demand (BOD5), temperature, total suspended solids (TSS), and total solids (TS) concentrations also changed with the season. The analysis of LULC changes within 1000-m buffer zones around the sampling stations revealed that agricultural and vegetation classes decreased; while built-up, waterbody and barren lands increased. Correlation analyses showed that BOD5, temperature, EC, TDS, and TSS had a significant relationship (5% level) with LULC types. The regression result indicated that BOD5 was sensitive to changing waterbody (predictors, R2 = 0.645), temperature was sensitive to changing waterbodies and agricultural land (R2 = 0.889); and EC was sensitive to built-up, vegetation, and barren land (R2 = 0.833). Waterbody, built-up, and agricultural LULC were predictors for TDS (R2 = 0.993); and waterbody, built-up, and barren LULC were predictors for TSS (R2 = 0.922). Built-up areas and waterbodies appeared to have the strongest effect on different water quality parameters. Scientific finding from this study will be vital for decision makers in developing more robust land use management plan at the local level.

An Analysis of the Morphological Changes of Surma River in Sylhet District Using Multitemporal Remote Sensing Images

The Surma River is one of the most important rivers in the northeastern part of Bangladesh, which has changed significantly throughout history. Very few studies have taken place to understand this river's complex behavior, which characterizes its morphology. The core objective of this research is to analyze the river dynamics to understand the morphological changes of the river from 1978 to 2021. Remotely sensed satellite images of 1978, 1989, 1999, 2011, and 2021 were secondary data. The whole working procedure is the correction of satellite images, application of normalized difference water index (NDWI), demarcation of the river bank line using bank line methods, quantification of the erosion-deposition using an overlapping method, demarcation of central line shifting, measurement of the river width and finally the sinuosity index metering for 43 years. The river has changed significantly in several locations within the period in Sylhet District. Ten bends, three segments, and 200 points were taken to quantify the change dynamics. The overall analysis found that the left bank shifted more than the right bank. According to the findings, the deposition rate (80.98m/year) of river Surma is almost double the erosion rate (42.11m/year), which causes a significant decline in river width from 163m in 1978 to 123m in 2011. After counting 200 sample points, the result concluded that the average central line shifted more than average (79.50m) at 38 points indicates three major locations- Kanaighat, Dakshin Banigram, and Lalargaon. Finally, the sinuosity index found that the river became more meander following its shifting movement except the ninth bend near Kandigaon. The riverine people indicated several anthropogenic factors, e.g., encroachment, illegal construction, pollution, illegal sand extraction, as the key issues which should be intervened and take necessary action.

Assessment of Water Quality of Surma River and Its Impacts on Urban Residents: The Case of Sylhet City Corporation

This study intends to assess the current water quality of the Surma River alongside Sylhet City and its impacts on urban residents. The water quality has been assessed by laboratory analysis considering a total of seven water quality parameters, viz. pH, DO, BOD, COD, TS, TSS and TDS and water samples were collected from four stations. The impacts of water quality on human health, fishing, the soil, agriculture and the surrounding environment are analyzed based on primary data collected through questionnaire survey covering a total of 200 respondents who resides at the bank of the river. The average values of parameters are DO 11.15 mg/l, BOD 1.77 mg/l, COD 25.27 mg/l, pH 7.2, TSS 131.5 mg/l, TDS 26.47 mg/l and TS 158 mg/l. Among of them only pH is within standard value. Respondent of the study area opined that they have no waste dumping station where they can put their waste. For that reason they compelled to dump waste into the river.Inadequate waste management system and lack of proper waste management initiatives accelerating the pollution exponentially. The scenario can be improved by implementing the recommendations made by the study, which can have the positive changes in the human and aquatic life, environment and ecosystem of the river area.