International Research Symposium on Pure and Applied Sciences (IRSPAS)

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Author: search.filters.author.Dayananda, M. D. N. R.Has files: Yes

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    Investigation of spatial distribution of fluoride in drinking water sources in CKDu prevalence areas in Sri Lanka using GIS
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Dayananda, M. D. N. R.; Botheju, W. S. M.; Perera, W. P. R. T.; Liyanage, J. A.
    Chronic Kidney Disease of unknown etiology (CKDu) has identified as a significant health burden in rural dry zone areas in Sri Lanka. Fluoride is recognized as a nephrotoxic contaminant which deteriorates the renal functions progressively and the drinking water could be the major source which is responsible for the disease occurrence. Therefore, the present study attempted to investigate the spatial distribution of fluoride in drinking water sources in CKDu prevalence hotspots in Sri Lanka using Geographical Information System (GIS). Triplicated drinking water samples were collected from 30 sampling locations (from dug wells) in each Grama Niladhari Division (GND) including Wewelketiya GND in Anuradhapura district, Ambagaswewa GND in Polonnaruwa district, Naminigama GND in Mathale district and Buddhangala GND in Ampara district (Reference site) in dry season, Sri Lanka (February – March, 2019). Fluoride contents of collected samples were analyzed using ion chromatography (Metrom Eco_IC instrument). Spatial distribution patterns were interpolated using inverse distance weighted (IDW) and spatial autocorrelation (Moran’s Index- MI) tools in ArcMap 10.2.2 software. Results indicated that the mean fluoride levels of the collected water samples of Ambagaswewa and Wewalketiya areas were 1.37 ± 0.66 mg/L and 1.26 ± 0.65 mg/L respectively and those results exceeded the Sri Lankan drinking water standards (SLS 614: 2013) (1.0 mg/L) but the mean fluoride levels relevant to Naminigama area (0.82 ± 0.59 mg/L) complied with the SLS standards. Further 80% of the samples in Ambagaswewa GND and 95% of samples in Wewalketiya GND were highly contaminated with fluorides which were exceeded the SLS standard limits. Significantly higher Fluoride concentration levels were shown in Ambagaswewa GND (P= 0.103) and Wewalketiya GND (P= 0.704) compared to the reference area of the study.As well as fluoride concentration of the reference area was evenly distributed (MI= -0.005) in very low levels compared to the selected hot spots. Fluoride distribution were clustered with higher levels (MI = 0.31) in Wewalketiya GND, and Fluoride levels were evenly distributed with higher levels in Ambagaswewa GND and Naminigama GND with the Moran’s Indices of -0.12 and -0.07 respectively. It can be concluded that fluoride can be one of the risk factors affecting the prevalence of the CKDu. As the people are at a risk with the long-term exposure to the high fluoride concentrations, it is very essential to innovate a proper and affordable drinking water treatment technology for the affected areas and findings of this study can be used as background water quality data in the design process
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    Estimation of crop management factor and conservation support practice factor of RUSLE model to assess vulnerability to soil erosion in Kalu Oya and Mudun Ela basins using GIS
    (Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Lekamge, M. L. D.; Dayananda, M. D. N. R.; Weerasinghe, V. P. A.
    Soil erosion is a serious environmental problem, which emerges from intense anthropogenic activities, agricultural practices and improper land use management. River basin soil erosion assessment enables to plan, conserve and manage the watershed areas and associated ecosystems. Revised Universal Soil Loss Equation (RUSLE) model is the most widely used model to predict the long term erosion rates in an area using rainfall-runoff erosivity factor, soil erodibility factor, slope length and steepness factor, crop management factor (C factor) and conservation support practice factor (P factor). Present study has been conducted to estimate the C and P factor to assess the vulnerability to soil erosion in Kalu Oya and Mudun Ela basins located in Gampaha district, Western province, Sri Lanka. The total catchment area of Kalu Oya and Mudun Ela basins (7°7'60" N and 79°54'0" E) are about 78 km2. C and P factor of RUSLE model were estimated using land use map and 30m resolution LANDSAT 8 OLI/TIRS satellite images acquired on 17th February, 2018 to determine the vulnerability of erosion and conservation status. The C factor values for barren areas and well protected areas were assigned from 1 - 0 respectively, whereas 0 - 1 range was used for the good conservation (0) and poor conservation (1) status of the prevailing land use patterns using the field observations and literature reviews. Spatial join tool of overlay analysis was used to obtain the combined effect of C and P factors and two separate thematic maps were derived using ArcGIS 10.2.2 version to represent the spatial distribution of both C and P factors according to five classes; low, moderate, high, very high and extremely high which represent the vulnerability to soil erosion. The study identified 9.94% of the total area with 0.00 - 0.01, 80.56% with 0.01 - 0.14, 0.61% with 0.01 - 0.20, 8.03% with 0.20 - 0.63 and 1.86% with 0.63 - 1.00 of C factor and 0.01% with 0.20, 0.61% with 0.20 - 0.40, 82.57% with 0.4 - 0.5, 1.45% with 0.50 - 0.60, 15.35% with 0.60 - 1.00 P factor. Significantly higher amount of erosion vulnerability areas were observed besides the tributaries. The study identified 9.01% of the total area under low erosion (0.00 - 0.02), 79.56% under moderate erosion (0.02 - 0.14), 0.61% under high erosion (0.14 - 0.20), 8.03% under very high erosion (0.20 - 0.63) and 1.86% under extremely high erosion (0.63 - 1.00) for combined effect of C and P factor. Moderate erosion could be reduced using suitable agronomic practices. Appropriate conservation measures have to be implemented for the areas under high, very high and extremely high vulnerability to soil erosion within the Kalu Oya and Mudun Ela basins to reduce sediment transport.