Browsing by Author "De Silva, K. V. N. T."

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Assessment of level of public knowledge, attitude, and perception towards sustainable mangrove forest conservation: a case study from Negombo region, Sri Lanka
(Assessment of level of public knowledge, attitude, and perception towards sustainable mangrove forest conservation: a case study from Negombo region, Sri Lanka, 2023) Wickramasingha, W. S. B.; Perera, W. W. A. M. R.; Kodithuwakku, K. C.; De Silva, K. V. N. T.; Karunarathne, D. M. S. D.
Mangroves have been an essential vegetative component not only in sustaining the balance of ecosystems but also in providing significant socio-economic benefits to the local communities such as fish, timber, and tourism opportunities to the local communities. Quantifying knowledge, attitudes, and perception (KAP) supports sustainable mangrove conservation by informing conservation efforts to address local needs and priorities and monitoring interventions' effectiveness over time. Thus, this study aims to determine the level of knowledge, attitudes, and perceptions of the public toward sustainable mangrove forest conservation in the Negombo region, Sri Lanka. Prior to data collection, a pilot study was conducted in the study area with 40 respondents and Cronbach's alpha (α = 0.819) reliability test was followed to test the reliability of the data. Data were collected via face-to-face interviews with randomly selected 395 respondents living near and around the northern region of the Negombo lagoon, which involved 8 Grama Niladhari Divisions. 51.39% of the individuals were male, while the remaining 48.61% were female, reflecting a commitment to gender equality. A Likert scale and correlation analyses were implemented using SPSS version 26 software to determine the community's knowledge, attitude, and perception (1-lowest and 5-highest). The finding shows that the level of knowledge of the community on the importance of sustaining mangrove forests was high from 3.92 to 4.72, the level of attitude was between 3.2 to 4.88, and the perception components from 4.47 to 4.83. There were significant gender differences in both attitude and perception toward mangrove forest conservation, with the female respondents achieving better scores than the male respondents, although there was no significant difference in their knowledge levels. Also, about 96.2% of respondents agree that the loss of mangroves will have negative impacts on the environment and the economics of the livelihood. Furthermore, most respondents believed that chemical pollution, illegal clearing, and development activities have a significant impact on the degradation of mangroves in the area. The correlation test showed that there was a strong positive correlation between knowledge and attitude (r = 0.901, p < 0.001), knowledge and perception (r = 0.795, p <0.001), and attitude and perception (r = 0.864, p < 0.001) respectively. They suggest that the most effective approach for preserving this ecosystem's survival is to engage in mangrove replanting through proper scientific monitoring, while also recommending the rectification of policy deficiencies and the execution of comprehensive strategies for mangrove conservation. The findings from this study may provide valuable information for future research, as well as assist government and stakeholders in enhancing the effectiveness of campaigns and programs focused on the sustainable management of mangrove forests.
Characterization of the water quality in the Rekawa lagoon, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) De Silva, K. V. N. T.; Wijeyaratne, W. M. D. N.
Rekawa lagoon is located in the Hambantota district in the Southern province of Sri Lanka. The lagoon is of high ecological and socio economic significance and is heavily utilized for aquaculture and fisheries purposes. The present study was conducted to assess the pollution status of selected sites in Rekawa lagoon in terms of water quality indices. The data was collected from five sampling sites in the lagoon; Site A: canal mouth, Site B: adjacent to residential areas, Site C: adjacent to agricultural lands, Site D: adjacent to hotels and shrimp farms, Site E: adjacent to mangrove forests. The water samples from each sampling site were analysed monthly for a period of six months from August 2023 to January 2024 to measure the water pH, salinity, turbidity, conductivity, DO (Dissolved Oxygen), TDS (Total Dissolved Oxygen), BOD5(Biological Oxygen Demand), temperature and Cr, Cd, Pb concentrations taking 5 replicates for each sample. In-situ parameters such as pH, salinity, turbidity, conductivity, DO, TDS, temperature were measured using multiparameter. The BOD5 values were measured according to APHA 2017. Heavy metal concentrations were measured using GBC SavantAA. The spatial and temporal variation of water quality parameters were assessed using one – way ANOVA followed by Tukey’s pairwise comparison by Minitab 17 software. Water quality index (WQI) was calculated from the water quality data. The WQI reflects moderate confidence due to the absence of microbiological parameters. The results of the present study indicated significant spatial variations of temperature, salinity, EC (Electrical Conductivity), pH, DO, BOD5, Cr, Cd, Pb and Zn concentrations. The highest mean surface water temperature was recorded at site C (32.5±0.11oC), highest mean surface pH at site A (8.35±0.06), highest mean conductivity at site A (28.48±0.28 mS/cm), highest mean water salinity at site A (10.31±0.21‰), highest mean DO at site A (8.09±0.01 mg/L), highest mean BOD5 at site C (4.77±0.02 mg/L), highest mean chromium concentration at site D (1899.00±0.00 ppb), highest mean cadmium concentration at site D (10.01±0.00 ppb), highest mean lead concentration at site D (157.02±0.00 ppb) and highest mean zinc concentration at site D (281.00±0.00 ppb). Salinity, EC, pH and temperature showed significant temporal variations among the sites. The highest mean surface water temperature was recorded in August, October and November (32.5 oC), highest mean salinity in August (12.00 ‰), highest mean conductivity in November (28.80 mS/cm) and highest mean pH in August (8.11). The highest WQI was recorded at site D (51.8) while the lowest was recorded at site E (26.6). According to the WQI the site D was categorized as poor while the other sites were categorized as good. The high load of organic pollutants released by the hotels and restaurants in the vicinity was identified as a possible cause for the degradation of water quality at site D as many point source wastewater outlets were identified at this site. Therefore, it is recommended to conduct adequate water quality monitoring and management activities in the Rekawa lagoon to ensure the continuous ecological and economic benefits acquired from the lagoon and to prevent the possible degradation.
Identification of soil erosion prone areas in Matale district in Sri Lanka using RUSLE model and bare soil index
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Jayasekara, J. M. P. M.; Mendis, C. C. D.; De Silva, K. V. N. T.; Kodikara, K. N.; Weerasinghe, V. P. A.
The Matale District is situated in the Central Province of Sri Lanka. It is roughly 1,993 km2 in size and is in the foothills of the central mountain range. Matale District is vulnerable to soil erosion, which causes serious problems for the local environment and agricultural activities. Soil erosion in Matale District is primarily caused by several factors, including rainfall, land use, slope, soil type and conservation practices. This study aims to assess the soil erosion vulnerability in Matale District, Sri Lanka, utilizing the Revised Universal Soil Loss Equation (RUSLE) model and Bare Soil Index (BSI). RUSLE Model, a Digital Elevation Model (15 * 15m), rainfall data, land use and land cover, soil maps, and cropping parameters were used to evaluate the severity of erosion throughout the Matale district. The RUSLE model was calibrated and utilized to determine the rates of soil erosion considering rainfall erosivity, soil erodibility, slope length and steepness, cover management, and conservation practices. Furthermore, the BSI was calculated using remote sensing techniques. The results of the study indicated that soil erosion vulnerability in Matale District varied significantly. The estimated annual average soil loss varied from 0 to 731.71t ha-1 yr-1 . Improved land management practices and forest cover were associated with lower rates of soil erosion, whereas steep slopes, poor vegetation cover, and intense land use practices were associated with higher rates. The BSI map further explains the soil erosion risk map. When comparing the BSI map with the soil erosion risk map, most of the areas with bare soil are prone to erosion. Paddy-cultivated areas, scrub lands, chena and other cultivated areas are prone to experience high levels of soil erosion when considering a land use map. The Red Yellow podzolic soil, Reddish Brown Earths, immature Brown Loams, Erosional remnants steep rock land, and various lithosols soil types are found in areas with severe soil erosion when comparing the soil and Soil Erosion Risk Maps. When comparing a slope map to a soil erosion risk map, areas with a high percentage of slope indicate high soil erosion. Areas with a low percentage of slope on a soil erosion risk map indicate less erosion. Based on the results, recommendations for soil conservation and sustainable land management strategies in the identified vulnerable areas in the Matale district include measures such as afforestation, contour farming, terracing, conservation agriculture practices, and education and awareness programs. This study contributes to understanding soil erosion vulnerability in Matale District and provides a foundation for further research and initiatives focused on sustainable land management and environmental conservation. Proper soil conservation practices should be implemented to safeguard natural resources, improve agricultural productivity, and assure long-term sustainability.