Institutional-Repository, University of Moratuwa
Welcome to the University of Moratuwa Digital Repository, which houses postgraduate theses and dissertations, research articles presented at conferences by faculties and departments, university-published journal articles and research publications authored by academic staff. This online repository stores, preserves and distributes the University's scholarly work. This service allows University members to share their research with a larger audience.
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Recent Submissions
item: Conference-Extended-Abstract
Integration of climate-informed flood hazard modeling and community perceptions for adaptive flood risk management in the Maha Oya river basin, Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2025) Vithurshika, J; Perera, GMCA; Chandrathilaka, K
The Maha Oya River Basin (MORB) in Sri Lanka experiences recurring floods threatening more than one million residents. However, flood management has traditionally emphasized physical hazard assessment, with limited integration of climate projections and community risk perceptions. This study develops a climate-informed flood hazard modelling framework and examines how exposure to hazard maps influences community risk perception, trust, and adaptive intent. Historical rainfall observations from four stations were quality-controlled, and bias-corrected CNRM-CM6-1-HR projections under SSP1-2.6 and SSP5-8.5 characterised future extreme rainfall. Gumbel frequency analysis and intensity-duration-frequency relationships generated 50-year design storms for historical and near-, mid-, and far-future periods, with the mid-future period selected as the critical period for both SSP1-2.6 and SSP5-8.5. HEC-HMS 4.13 and 2D HEC-RAS 6.6 generated flood hazard maps, achieving an accuracy of 0.92 and bias score of 0.99 during calibration against the May 2016 flood, and 0.83 and 1.42 during validation against the November 2025 flood. Simulated inundated area was 41.72 km² historically, rising to 51.26 km² (+22.86%) under SSP1-2.6 and 46.00 km² (+10.25%) under SSP5-8.5. Six flood-prone GN divisions in Pannala and Divulapitiya were identified, and 40 households within mapped inundation zones were purposively surveyed, giving a 97.6% response rate. Following exposure to the hazard maps, 87.5% of respondents reported improved understanding of flood risk, 85% reported increased concern about future flooding, and 97.5% expressed willingness to adopt adaptation measures. These findings highlight the potential value of integrating climate-informed hydrological and hydrodynamic modelling with participatory risk communication to improve risk awareness and support adaptive flood-risk management in the MORB.
item: Conference-Extended-Abstract
A Comparative analysis of inter-regional air pollution trends in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2026) Wickramasinghe, USN; Imbulana, SM; Manatunge, JMA; Chandrathilaka, K
Air pollution is a major environmental and public health concern in Sri Lanka, yet island-wide comparative evidence covering both fine and coarse particulate matter remains limited. This study evaluated spatial and temporal patterns of PM2.5 and PM10 using daily observations from twenty National Building Research Organisation monitoring stations from March 2020 to December 2024. Daily rainfall records were available for nine stations and were used to examine the relationship between precipitation and particulate concentrations. Descriptive statistics, annual and seasonal comparisons, Pearson correlation and compliance assessment against World Health Organization guidelines and Sri Lankan national standards were applied. Mean PM2.5 concentrations ranged from 15.10 μg/m³ at Nuwara Eliya to 28.28 μg/m³ at Badulla, while mean PM10 concentrations ranged from 21.86 μg/m³ at Nuwara Eliya to 40.11 μg/m³ at Jaffna. All twenty stations exceeded the World Health Organization annual guidelines for both pollutants, although period-average concentrations remained within the Sri Lankan national annual standards. The lowest annual concentrations occurred in 2021, followed by substantial increases from 2022 onwards. Both pollutants were consistently higher during the northeast monsoon period. Rainfall showed only weak negative-to-negligible relationships with particulate concentrations. The results demonstrate substantial spatial and temporal variability and indicate that regional transport and seasonal atmospheric processes are important considerations for particulate pollution management in Sri Lanka.
item: Conference-Extended-Abstract
Advancing SDG 6 through integrated water conservation in Sri Lanka: a review-based framework and implementation pathway
(Department of Civil Engineering, University of Moratuwa, 2026) Edirisinghe, CN; Manatunge, JMA; Imbulana, SM; Chandrathilaka, K
Sri Lanka has several existing water conservation measures, including rainwater harvesting, wastewater reuse, demand-side efficiency, green building provisions and policy instruments. However, these measures are often implemented separately, limiting their collective effectiveness and contribution to Sustainable Development Goal 6. This study examines how existing conservation measures can be better integrated within the Sri Lankan context. A structured review-based qualitative thematic synthesis was conducted using journal articles, Sri Lankan policy documents, technical guidelines, project reports and international best-practice sources, with evidence organised and coded to identify recurring conservation measures, implementation barriers and enabling mechanisms. The thematic synthesis resulted in four themes: water supply, treatment and reuse systems; demand-side water use and end-use efficiency; built environment and design-based strategies; and governance, policy and economic instruments. The synthesis identifies fragmented implementation, institutional coordination gaps, inadequate monitoring and inconsistent user adoption as recurring constraints across the four thematic areas. Based on these findings, a Multi-Layer Water Conservation Framework is proposed to connect policy and governance, infrastructure and design, technology and systems, and user and demand considerations. A phased Implementation Pathway Framework further translates these components into short-, mediumand long-term actions aligned with relevant national SDG 6 targets and water-sector priorities. Together, the frameworks provide a structured basis for moving from isolated conservation measures towards more coordinated water conservation planning in Sri Lanka, thereby supporting progress towards SDG 6.
item: Conference-Extended-Abstract
Developing an empirical relationship between rainfall characteristics and microplastic emissions in an urban river
(Department of Civil Engineering, University of Moratuwa, 2026) Abeysekara, T; Imbulana, S; Chandrathilaka, K
Rainfall runoff transports microplastics into urban rivers, but concentration responses vary between events. This study analysed a secondary dataset from the Takano River, Kyoto, Japan, to evaluate river flow as a predictor of microplastic concentration. Records for particles between 10 and 300 micrometres were examined using time series, correlations and regression. Light rainfall produced an early concentration peak, moderate rainfall showed coincident flow and concentration peaks, and heavy rainfall produced delayed peaks during flow recession. A power-law model fitted to the light and moderate events explained 84 percent of the variation in log-transformed particle concentration. Leave-one-out cross-validation gave a coefficient of determination of 0.81. River flow therefore provided a useful predictor within the observed event domain. However, the model estimates total concentration at the monitoring site without separating upstream inputs from local rainfall wash-off. Transfer to other catchments requires validation because land use, surface resistance and microplastic sources can alter transport. Heavy rainfall requires consideration of storage, remobilisation and delayed delivery.
item: Conference-Extended-Abstract
Assessing the effects of consecutive extreme rainfall events under future climate scenarios on reservoir storage and spillway requirements: a case study of Manankattiya reservoir, Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2026) Malwattegedara, J; Gunawardhana, L; Rajapakse, L; Chandrathilaka, K
Irrigation reservoirs in the dry zone of Sri Lanka are designed for a single design flood, so the damaging condition arises when a second heavy storm arrives while the reservoir is still full. This study examines how consecutive extreme rainfall events change under future climate scenarios and affect the storage and spillway of Manankattiya Reservoir. Daily observed rainfall from 1994 to 2024 generated 12 projection series from three global climate models, under two shared socioeconomic pathways and two future periods, giving 60 model-years per scenario; as record lengths differ, counts are compared as events per year. An extreme event was defined by a 200 mm event depth and a compound event by two extremes less than seven days apart. Of 50 compound events identified, 22 were routed through a HEC-HMS rainfall runoff model. By 2081-2100, compound events become over four times more frequent under the high-emission pathway, rising from 0.06 to 0.30 events per year, and the share of storms qualifying as extreme rises from 3.2% to 8.3%. Each event delivers 25 to 47 million cubic metres (MCM) to a reservoir holding 6 MCM at full supply, and a crest length near 24 m is indicated to keep the peak level below the bund top. As the routing uses daily rainfall for a catchment with a 185-minute lag and a derived elevation-storage relationship, this is a screening value requiring confirmation against the probable maximum flood. Reservoir safety and spillway design must therefore account for consecutive extremes rather than a single design flood.