Browsing by Author "Rajapakse L"

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    Integrated flood risk management for urban resilience: A multi-method framework combining hazard mapping, hydrodynamic modelling, and economic impact assessment
    (Elsevier B V on behalf of the College of Civil Engineering, Tongji University, 2025-09-01) Jayawardane P; Rajapakse L; Siriwardana C
    Flooding has become an emerging global catastrophe, generating considerable damage to both infrastructures and lives. Despite the critical need for quantitative assessments of both flood damage and the effectiveness of flood mitigation measures, most existing studies have focused on isolated aspects of flood risk. Only a very limited number of studies have comprehensively integrated hazard mapping, hydrodynamic simulations, and economic damage estimations to evaluate the real-world impact and effectiveness of flood mitigation measures (FMMs). This study presents a multi-method approach to evaluate the performance of such established structural FMMs. Initially, hazard assessments for two selected case study areas, the Colombo Metropolitan Area in Sri Lanka and Auckland, New Zealand, two flood-prone cities with contrasting geographical contexts. Flood inundation mapping for the Madiwela South Diversion, Colombo, Sri Lanka, was performed using hydrodynamic modeling to demonstrate the reduction in flood inundation area and depth after the implementation of the measure, considering six (6) design return periods (RPs). Subsequently, tangible and intangible property damage estimations for “without FMMs” and “with FMMs” were evaluated to identify the benefit of responding to flood conditions, utilising a vulnerability-based economic analysis. In addition to damage estimations, the study adopts a novel approach by conducting an investment viability analysis to find the Benefit-to-Cost ratios and Net Present Value of nine (9) selected FMMs implemented by Sri Lanka Land Development Co-operation (SLLDC). The FMMs implemented by SLLDC were selected from Colombo, Sri Lanka. The quantified damage estimates revealed a reduction in flood damages ranging from 39 % to 63 %, alongside a decrease in flood inundation depths between 9 % and 12 %, and the results underscore the significant effectiveness of FMMs in managing urban flooding and minimising its impacts. This cross-disciplinary methodology enables a transferable framework for resilience-oriented urban planning in diverse hydrological and geographical contexts.
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    Systematic Mapping of Global Research on Disaster Damage Estimation for Buildings: A Machine Learning-Aided Study
    (MDPI (Basel, Switzerland), 2024-06-20) Rajapaksha D; Siriwardana C; Ruparathna R; Maqsood T; Setunge S; Rajapakse L; De Silva S; Witt E; Bilau AA; Sun B
    Research on disaster damage estimation for buildings has gained extensive attention due to the increased number of disastrous events, facilitating risk assessment, the effective integration of disaster resilience measures, and policy development. A systematic mapping study has been conducted, focusing on disaster damage estimation studies to identify trends, relationships, and gaps in this large and exponentially growing subject area. A novel approach using machine learning algorithms to screen, categorise, and map the articles was adopted to mitigate the constraints of manual handling. Out of 8608 articles from major scientific databases, the most relevant 2186 were used in the analysis. These articles were classified based on the hazard, geographical location, damage function properties, and building properties. Key observations reveal an emerging trend in publications, with most studies concentrated in developed and severely disaster-affected countries in America, Europe, and Asia. A significant portion (68%) of the relevant articles focus on earthquakes. However, as the key research opportunities, a notable research gap exists in studies focusing on the African and South American continents despite the significant damage caused by disasters there. Additionally, studies on floods, hurricanes, and tsunamis are minimal compared to those on earthquakes. Further trends and relationships in current studies were analysed to convey insights from the literature, identifying research gaps in terms of hazards, geographical locations, and other relevant parameters. These insights aim to effectively guide future research in disaster damage estimation for buildings.