Browsing by Author "Balasooriya, T. A. P."

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    Land-use Change of Muthurajawela Wetland from 2013-2023 using Remote Sensing and Geographic Information System
    (Faculty of Science, University of Kelaniya Sri Lanka, 2024) Senanayake, S. A. S. J.; Balasooriya, T. A. P.; Vilvarashah, B.; Jayalal, H. A. N. A.; Pitawala, L. M. K. G.; Weerasinghe, V. P. A.
    Muthurajawela marsh, Sri Lanka's largest coastal saltwater peat bog, is located on the western coast and spans from Wattala to Negombo. This wetland, along with the Negombo Lagoon, forms a sustainable ecosystem and serves as an economical source and a drainage area. It has faced significant depletion due to industrialization and urbanization since 1997, with accelerated changes in the last decade. This signified a need to analyse land-use changes to develop effective conservation strategies. Remote sensing and GIS technologies were proposed for this assessment to formulate future conservation management plans. The main objective of the study involved identification of land-use patterns which occurred in the Muthurajawela wetland over the past 10 years. Specific objectives included the analysis and processing of necessary data to produce land-use maps via GIS and remote sensing and the quantification of land-use change over the study period. Landsat 8/9 OLI images of the Muthurajawela wetland for the years 2013, 2018 and 2023 were obtained from EOS Data Analytics (EOSDA) LandViewer and each image was analysed using ArcGIS software after pre-processing. Supervised classification was carried out on the clipped images under three classes: water bodies, marshlands, urbanization, and land-use maps were prepared. Areas and percentage differences of the selected classes were calculated. Accuracy assessment was carried out using Kappa coefficient. The analysis revealed that, from 2013 to 2018, water bodies decreased by 26.02% (from 0.3571 to 0.2642 km2), urbanization decreased by 16.71% (from 0.6827 to 0.5723 km2), while marshlands increased by 27.38% (0.2931 to 0.3734 km2). From 2018 to 2023, water bodies increased by 24.94% (from 0.2642 to 0.3301 km2), urbanization increased by 11.83% (from 0.5723 to 0.64 km2), and marshlands decreased by 10.69% (from 0.3734 to 0.3335 km2). From 2013 to 2023, water bodies have decreased 1.07%, marshlands increased by 16.7%, and urbanization decreased by 4.34%. Calculated Kappa coefficients were 89.17 for 2013, 74.25 for 2018, and 91.98 for 2023. These high Kappa values indicated a strong agreement between the classified maps and the ground truth data. The overall accuracy values were above 80% for all years (93.33% for 2013, 95.00% for 2018, 86.67% for 2023). Land-use of Muthurajawela marsh resulted in an increase in marshland area from 2013 to 2023, indicating growth of the marshland along with a slight percentage decrease in water bodies and a reduction in land development for urbanization. Although measures taken to restore marshlands appear successful, further measures to protect water bodies are recommended to be applied after further research. Therefore, this analysis has displayed the dynamic nature of the land-use of the wetland ecosystem along with its interactions with human activities.