Browsing by Author "Dikkumbura, H.K.U.S."

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    Rainfall-Runoff-Inundation (RRI) model for flood analysis in Attanagalu Oya basin, Sri Lanka
    (Department of Zoology and Environmental Management, University of Kelaniya, Kelaniya, Sri Lanka., 2016) Dikkumbura, H.K.U.S.; Weerasinghe, V.P.A.
    Floods are one of the most critical forms of natural hazard in global and local context. In the case of large scale flooding, it is important to identify the flood inundation areas and map the areas that undergo flooding for future flood management plans. This study analyzed rainfall-runoff and inundation in the Attanagalu Oya basin with the Rainfall-Runoff-Inundation (RRI) model that simulates the rainfall-runoff and inundation processes simultaneously based on two-dimensional diffusion wave equations. The applicability of RRI model to simulate flood inundation areas over the Attanagalu Oya basin was also investigated. RRI model simulation was conducted with satellite-based topographical data and daily satellite-based rainfalls for the period of 15th to 18th May of 2010 which was the most recent destructive flood occurred in Sri Lanka.Water depths on slope, water depths on river and river discharges at a specific time step were obtained as output. The model performance was evaluated using satellite-based vector flood map in 2010 obtained from the Disaster Management Centre and river discharge data at Dunamale obtained from the Department of Irrigation, Sri Lanka. The simulation results showed 74.31 % accuracy in downstream flood inundation extent with vector flood map. The simulation under-predicted the flood inundation in upstream areas and tributaries due to the coarse resolution of digital elevation model. The relative error of river discharge data shows some underestimation of simulated flow discharges as it is -20.17 %. The model simulation was found to be capable of obtaining the peak flood inundation extent in downstream of basin due to its flat topography. RRI model can be used for the ungauged basins with no flow data available as its simplicity, requiring only rainfall input.
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    Role of the coastal community and the government in sustainable utilization and management of coastal resources in Unawatuna, Sri Lanka
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Moragoda, M.K.N.P.; Ranasinghe, O.R.; Dikkumbura, H.K.U.S.; Kalaotuwawe, K.M.B.P.; Karunapala, H.M.B.N.; Dilini, R.M.A.; Gamanayake, B.G.N.N.; Kuruppuarachchi, H.D.; Chandrasekara, W.U.
    Unawatuna is a coastal town in southern Sri Lanka, and its safe sandy beach is popular among local and overseas tourists. Since this beach generates a considerable amount of income through tourism, it is of paramount importance to manage and sustainably utilize its coastal resources in order to improve tourism and quality of life of the local community. With this view, a field survey was carried out on this location in October 2014 to assess the role of the local coastal community and the local government authorities in sustainable utilization, management and governance of coastal resources in Unawatuna beach. In this survey, a questionnaire based survey on the local community (n = 20) as well as on randomly selected individuals (n = 15) on the beach was carried out by holding face-to-face interviews. In addition, a questionnaire survey on the chief executive officers of the local authorities in the area viz. Area Engineer’s office of Coast Conservation Department (CCD) in Unawatuna, Southern Provincial Office of Central Environmental Authority (CEA), Habaraduwa Police Station and Habaraduwa Pradeshiya Sabhawa was also carried out by holding face-to-face interviews. Data obtained from both components of the survey were subjected to analyses and a SWOT analysis was carried out. The major strengths identified by the analysis included the presence of a variety of natural resources and cultural attractions on the beach. The educational level of people in the beach surroundings was high where 58.8% had above O/L educational qualifications. Further, the beach is cleaned daily by organized groups in the community (58.82%) so that the cleanliness of the beach was high (76.47%). The local community also received a fairly high income from tourism (73.33%). The CCD and CEA are strongly involved in coastal erosion prevention programmes, conducting awareness programs for the stakeholders on the beach area, implement policies, plans, projects and strategies to conserve the coastal resources in the area. The tourist police unit of Habaraduwa police station maintains law and order in the area and take strict legal actions against illicit drug and liquor trade and use. Further, the Habaraduwa Pradeshiya Sabhawa carried out public utility services including daily removal of garbage from the surrounding area. The major weaknesses identified were lack of awareness (15.21%) and lack of commitment (19.56%) of stakeholders on coastal resources management practices and difficulties in implementing laws and regulations (6.52%). There are opportunities for improvement of recreational, beach protection and development activities, and involving unemployed persons of the local community (23.53%) in tourism. The major threats were beach pollution by sewage and solid waste (25%), interferences by external parties such as large scale hotel owners and politicians (20.83%), high government taxes (37.5%), illegal constructions on the beach façade (20.83%) and coastal erosion due to unplanned construction of a break water. The present study highlights the involvement of a co-management strategy in Unawatuna beach area on the governess and management of coastal resources with positive inputs from both the local government authorities and the stakeholder community. Reinforcing and strengthening the existing co-management strategy is recommended for the proper governess, management and sustainable utilization of coastal resources in the Unawatuna coastline.