Browsing by Author "Madhurshan, R"

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    Effects of covid-19 lockdown on lst, ndvi, lulc, and uhi: Dehiwala-Mount Lavinia case study
    (IEEE, 2023-12-09) Madhurshan, R; Mushmika, PAS; Edirisooriya, KVUI; Ishankha, WCA; Dauglas, DLPM; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
    The COVID-19 pandemic has had a profound global impact since its outbreak in late 2019. To curb the spread of the virus, measures were implemented to control its transmission, such as reducing human activities, shutting down industries, minimizing transportation, and practicing social distancing. A case study focused on the Dehiwala-Mount Lavinia suburb analyzed various environmental indicators during normal working days in April 2019 and the lockdown phase in April 2020. Landsat 8 (TIRS/OLI) images, processed with ArcMap 10.8.2 software, were used to examine the impact of the lockdown on environmental conditions by comparing Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI), Land Use/Land Cover (LULC), and Urban Heat Island (UHI). The results revealed a decrease in LST and an increase in NDVI during the lockdown. The analysis of LULC showed increased vegetation growth near the Aththidiya wetland area. A relatively cooler UHI was observed in 2020 compared to the year 2019. These findings underscore the influence of human activities on UHI and highlight the importance of urban planning and mitigation strategies to address UHI effects on local climates.
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    Enhancing operational strategies in water reservoir management through satellite imagery: analysing temporal anomalies in water surface variations for climate adaptation under seasonal changes
    (Business Research Unit (BRU), 2024) Madhurshan, R; Dhananjaya, KIK; Keerthi, T; Dassanayake, SM; Chao, Z
    Climate change variations have significant adverse impacts on water resources, particularly in regions where the water supply is primarily dependent on reservoir systems. For efficient management of water resources, it is essential to comprehend the dynamics of reservoir water levels and climate-driven anomalies. Quantitatively appraising the water budget is crucial for enhancing socio-economic water and energy demands. Analyzing fluctuations in water levels and cyclic patterns of drought seasons due to climate change can significantly aid in the pre-planning and managing reservoir systems. This study aims to enhance water reservoir management by using satellite imagery to identify drought periods through surface water area analysis. With the fusion of Landsat 8 and Sentinel-1 data, this research focuses on mapping water surface changes at the Victoria Lake reservoir, Sri Lanka, using the Normalized Difference Water Index (NDWI) from 2018 to 2023. Both satellite data were acquired and subsequently processed on the Google Earth Engine platform (GEE). The resulting maps were created using ArcMap desktop software. The correlation coefficient observed between Landsat 8 and Sentinel-1 NDWI area measurements is 0.771, indicating a strong relationship between the two datasets. This high correlation underscores the reliability of using both sources to comprehensively analyze water surface area. Factors such as sensor calibration, atmospheric conditions, and data processing techniques can affect recorded values and correlations. Results revealed a cyclic pattern in water levels, with a notable trough in March 2019, followed by a significant drop lasting until March 2022, and another rapid decline observed within the subsequent year. Integrating satellite imagery in monitoring and decision-making processes offers a valuable tool for addressing the challenges of water and energy management under climate anomalies.
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    Identification of optimum replacement ratio of processed quarry dust as a substitute for sand in cement plastering
    (Department of Earth Resources Engineering, 2023-08-28) Madhurshan, R; Anuttara, RNS; Kannangara, KKEU; Illankoon, IMTN
    The demand for sand is increasing due to construction activities. River sand scarcity causes illegal mining and environmental damage. The construction industry faces negative impacts if river sand becomes unavailable or scarce. Therefore, finding a suitable substitute is essential for the sustainability of the construction industry as well as preventing further degradation of the river ecosystem. Quarry dust, a byproduct of crushing is studied as a potential substitute. The investigation assessed the feasibility of using quarry dust as a partial replacement for river sand in wall plaster. Quarry dust was utilised to achieve the desired particle size distribution equivalent to that of sand. Five types of cement-sand-quarry dust wall plaster mortars were made. The volume ratios between sand and quarry dust were kept at 1:0, 4:1, 2:1, 3:2, and 0:1 while maintaining a constant cement amount for all mixtures. Then the strength and durability of plastering mortar were examined using destructive and non-destructive test methods. The obtained results were compared with wall plaster made from 100% sand. Results demonstrated that the optimal combination of strength, durability, and workability was achieved when using a sand-to-quarry dust ratio of 2:1. Also, this mixture reduced plastering mortar cost by 6%, recommending replacing 1/3 of the sand with resembled quarry dust for plastering mortar.