WATER QUALITY ASSESSEMENT USING GEOGRAPHIC INFORMATION SYSTEM TECHNIQUES
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Abstract
The study addressed the critical challenge of ensuring safe and sustainable borehole water quality in the University of Benin, Benin City, Edo Satae, Nigeria, where contamination risks from anthropogenic and environmental factors threaten public health. The study aimed to assess spatial variations in borehole water quality, evaluate compliance with national and international standards such as the NSDWQ and WHO standard and visualize contamination risk zones using GIS techniques.
Geographic coordinates were obtained using a GPS navigation tool called coordinate and water samples for laboratory analysis were collected at three borehole sites: A, B and C and their respective distribution points. Thirty-four physicochemical and microbial parameters were analyzed in accordance with the APHA standard laboratory procedures. The Weighted Arithmetic Water Quality Index (WAWQI) method was applied to compute the WQI for each sampling point. The results were integrated into ArcGIS Pro software, where shapefiles were created and thematic maps generated to show spatial distribution of WQI and individual parameters relative to environmental features such as septic tanks and drainage channels. The results of the pH, electrical conductivity, turbidity, total dissolved solids, values ranged from 4.8 to 6.0, 110 to 305 µS/cm, 3.48 to 4.04 NTU and 56 to 153 mg/L respectively. Calcium and Magnesium ranged from 2.87 to 7.14 mg/L and 1.61 to 4.00 mg/L respectively corroborating the low hardness values of 13.8 to 37.6 mg/L.
Concentrations of iron, manganese, zinc, copper ranged from 0.210 to 0.327 mg/L, 0.045 to 0.070 mg/L, 0.107 to 0.167 mg/L and 0.017 to 0.026 mg/L respectively. Microbiological results revealed that total heterotrophic bacterial counts were present in Borehole B and distribution points A and C at 10 × 10³ CFU/mL, all samples tested negative for coliforms and E. coli, indicating the absence of fecal contamination. Boreholes points A and B had WQI values of 61.27 and 57.30, inferring good quality, while Borehole C, distribution points A, B and C exhibited higher WQI values of 73.94, 82.79, 79.64 and 98.80 respectively reflecting post-storage contamination and influence from surrounding activities having a water quality grade of poor in line with the WHO and NSDWQ standards. The study concluded that GIS proved highly effective in visualizing spatial water quality variations and identifying areas at risk of contamination.
Geographic coordinates were obtained using a GPS navigation tool called coordinate and water samples for laboratory analysis were collected at three borehole sites: A, B and C and their respective distribution points. Thirty-four physicochemical and microbial parameters were analyzed in accordance with the APHA standard laboratory procedures. The Weighted Arithmetic Water Quality Index (WAWQI) method was applied to compute the WQI for each sampling point. The results were integrated into ArcGIS Pro software, where shapefiles were created and thematic maps generated to show spatial distribution of WQI and individual parameters relative to environmental features such as septic tanks and drainage channels. The results of the pH, electrical conductivity, turbidity, total dissolved solids, values ranged from 4.8 to 6.0, 110 to 305 µS/cm, 3.48 to 4.04 NTU and 56 to 153 mg/L respectively. Calcium and Magnesium ranged from 2.87 to 7.14 mg/L and 1.61 to 4.00 mg/L respectively corroborating the low hardness values of 13.8 to 37.6 mg/L.
Concentrations of iron, manganese, zinc, copper ranged from 0.210 to 0.327 mg/L, 0.045 to 0.070 mg/L, 0.107 to 0.167 mg/L and 0.017 to 0.026 mg/L respectively. Microbiological results revealed that total heterotrophic bacterial counts were present in Borehole B and distribution points A and C at 10 × 10³ CFU/mL, all samples tested negative for coliforms and E. coli, indicating the absence of fecal contamination. Boreholes points A and B had WQI values of 61.27 and 57.30, inferring good quality, while Borehole C, distribution points A, B and C exhibited higher WQI values of 73.94, 82.79, 79.64 and 98.80 respectively reflecting post-storage contamination and influence from surrounding activities having a water quality grade of poor in line with the WHO and NSDWQ standards. The study concluded that GIS proved highly effective in visualizing spatial water quality variations and identifying areas at risk of contamination.
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