Browsing by Author "Jayasekara, J. M. P. M."

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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.
Investigating the effluent quality of a sewage treatment plant in the Kelaniya area: A temporal analysis
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Jayasekara, J. M. P. M.; Najim, M. M. M.
Sewage treatment focuses on effectively removing contaminants from sewage to produce an effluent that is safe for discharge into the environment or reuse. Monitoring the effluent quality of a wastewater treatment plant is crucial for maintaining the treated effluent quality. There are growing concerns about the potential environmental impacts of the selected sewage wastewater treatment plant (SWWTP). However, there is a lack of comprehensive research to assess the actual impact of SWWTP on the local environment. Hence, the current study investigated the quality of the effluent of the selected SWWTP. This study was conducted by analysing variations of effluent quality parameters over 6 months (August 2023 to January 2024). Water samples were collected monthly and analysed for key water quality indicators using APHA methods. Temperature, pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Total Dissolved Solids (TDS), conductivity, salinity, and flow velocity were measured as key water quality indicators. The values of each parameter were compared with the tolerance limits for the discharge of wastewater or effluent into Inland Surface Waters presented by the National Environmental (Protection and Quality) Regulations. The temporal variations of the studied parameters of water samples were statistically analysed using a One-way ANOVA. Results suggest that COD values exceeded the standard values in August (654±16.8 mg/L), October (336.5±35.4 mg/L), November (273±16.8 mg/L), and January (95.2±11 mg/L). TSS values exceeded the standard values in August (87±14.2 mg/L) and October (60±1.74 mg/L) and Dissolved oxygen did not reach the standard values in October (4.47±0.09 mg/L) and November (4.46±0.03 mg/L). Nitrate concentration exceeded the standard values in August (16±1.14 mg/L) and January (13.54±1.04 mg/L). All the other parameters lay within the range of standard values. The cluster analysis of water quality parameters was used to identify the similarities between the sampling sites, and it revealed that effluent released into the environment in August has very different water quality values than other sampling months. All the parameters except pH exhibit significant temporal fluctuations. Low DO level suggested limitations in the aeration process or overload of the organic matter. Low DO levels can affect microbial activities and chemical reactions. Ultimately this can lead to elevated levels of COD and BOD. In addition, sand filtration and carbon filtration are not sufficient to remove soluble organic matter in the water. Therefore, it can be concluded that this treatment plant has some environmental implications due to high COD, TSS, DO, and nitrate levels. Further analysis of each step of the wastewater treatment plant is needed to thoroughly understand the causes of variations in the water quality parameters.