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
Evaluating irrigation water supply reliability under variable rainfall: the role of reservoir regulation and managed diversion in the Nachchaduwa sub-catchment, Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2026) Heshani, T; Perera, C; Chandrathilaka, K
Irrigation water availability in Sri Lanka’s dry zone is affected by seasonal and inter-annual rainfall variability, but reservoir storage and trans-basin diversions can buffer these fluctuations. This study evaluates the role of reservoir regulation and managed diversion in irrigation water reliability in the Nachchaduwa sub-catchment, Sri Lanka. A continuous semidistributed HEC-HMS model was developed using historical rainfall, reservoir-level and diversion data to represent rainfall–runoff processes, storage and managed water transfers. The model reproduced reservoir-level dynamics with NSE values of 0.453 and 0.626 for calibration and validation, respectively, with RSR of 0.70 and 0.60 and PBIAS of 0.36% and 0.05%. Although calibration performance was limited for short-term variability, the low PBIAS indicated close agreement in overall water balance. Seven-day cumulative rainfall showed the strongest, but weak, association with diversion, indicating that diversion is also influenced by reservoir storage and operational decisions. Despite rainfall variability, irrigated area remained comparatively stable, highlighting the buffering role of reservoir regulation and managed diversion. The results demonstrate that irrigation reliability is governed by the interaction of local rainfall, external water transfers, reservoir storage and operational management.
item: Conference-Extended-Abstract
Development of a wastewater management framework for environmental laboratories in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2026) Godagamapala, DGMA; Imbulana, SM; Manatunge, JMA; Chandrathilaka, K
Laboratories conducting environmental analyses generate highly toxic wastewater containing strong mineral acids, heavy metals, organic solvents, and residual analytical reagents. Yet, no specific national guidelines exist for managing and discharging it. This study assessed wastewater management practices at six major environmental laboratories in Sri Lanka through questionnaire surveys and site assessments, and conducted physicochemical and heavy-metal analyses of effluent from two representative sites. Survey results show that 66.7% of laboratories discharged wastewater without treatment, while 80% were unaware of applicable regulations. Laboratory analyses recorded pH = 3.11 ± 3.68, low biodegradability (BOD/COD <0.3), and heavy-metal concentrations exceeding Central Environmental Authority (CEA) Schedule I inland surface-water discharge standards, with maximum exceedances of 7 times for iron, 5 times for chromium, and 7 times for manganese. The chemical oxygen demand (COD) analysis was identified as the principal source of chromium contamination of laboratory wastewater. Based on the empirical findings of the study, a five-pillar and three-tier wastewater management framework was proposed, incorporating Green Analytical Chemistry, five-stream waste segregation, tiered on-site treatment, documentation of regulatory compliance, and institutional capacity building. The framework is scalable from small-scale academic laboratories to large government institutions and uses locally available materials and existing regulatory infrastructure, offering a practical pathway toward safer and more responsible laboratory wastewater management.
item: Conference-Extended-Abstract
Optimising building design for cinnamon oil refinery centres: a study of air circulation and occupational safety
(Department of Civil Engineering, University of Moratuwa, 2026) Hapuarachchi, P; Madusanka, P; Siriwardana, A; Kalanika, VLE; Chandrathilaka, K
Cinnamon oil refinery centres in Sri Lanka are commonly operated in naturally ventilated, semi-enclosed buildings where boilers, steam distillation units and cinnamon leaf storage can create localised heat accumulation and weak airflow regions. This study optimised the building design of such refinery centres by evaluating existing layout conditions, measured thermal and airflow data and computational fluid dynamics (CFD)-based design alternatives. Twelve refinery centres were initially observed and one representative refinery at Berathuduwa, Galle was selected for detailed investigation. Field data were used to prepare and validate an ANSYS Fluent model. The validated model was then applied to compare design variants including storage arrangement, boiler relocation, inlet opening, outlet opening, inlet-outlet combination, monitor roof, roof rise and optimised layouts. Results showed that one-sided ventilation improvements were not sufficient. The best performance was obtained by combining a clear inlet to outlet airflow corridor, non-obstructive storage placement, side-based boiler location and supportive roof volume. The study proposes practical guidelines for improving natural ventilation, reducing worker-zone thermal exposure and supporting occupational safety in small- and medium-scale cinnamon oil refinery centres.
item: Conference-Extended-Abstract
Indoor air quality assessment in cinnamon oil refinery centres in Sri Lanka using PTM 600: identifying ventilation-related health risks
(Department of Civil Engineering, University of Moratuwa, 2026) Lakshitha, K; Madusanka, P; Siriwardana, A; Kalanika, E; Chandrathilaka, K
This field-based case study assessed indoor air quality and ventilation-related occupational exposure conditions in a selected cinnamon oil refinery centre in Beruthuduwa, Galle, Sri Lanka. A preliminary questionnaire survey was conducted among 48 respondents from 12 refinery environments (24 workers, 12 owners and 12 community members), including questions on symptoms experienced during refinery operation. Detailed monitoring was then carried out at one selected refinery during one complete, approximately seven-hour cinnamon oil distillation cycle. A PTM 600 portable monitor was used at five repeated operational points and one supplementary elevated leaf loading point to measure CO₂, CO, SO₂, NO₂, O₃, VOC, PM₂.₅, PM₁₀, temperature and relative humidity; inlet and outlet air velocities were also measured. The highest CO process cycle mean occurred at the boiler zone (P2: 29.81 ppm), while the strongest particle levels occurred at the boiler and oil separator zones (PM₂.₅: 415 and 404 μg/m³ at P2 and P3; PM₁₀: 433 and 435 μg/m³ at P2 and P3). The supplementary leaf loading point identified a short-duration, task-based pathway for hot humid vapour and particles. Measured mean air velocity was approximately 2.20 m/s at the inlet and 0.23 m/s at the monitored outlet; these point measurements indicate a large local airflow difference but do not by themselves quantify overall ventilation effectiveness. Among workers, headache, eye irritation and cough were reported by 100%, nasal symptoms by 95.8%, and dry/sore throat by 62.5%. These self-reported symptoms were used as supporting evidence and do not establish pollutant-specific causality. The findings support source control at the boiler and vessel opening, improved exhaust pathways, safer leaf loading practices, personal protective equipment, worker rotation and follow-up monitoring.
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.