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.
 Research Publications |  Thesis & Dissertation |  E- Books |
 UoM Journal Publications |  UoM Conference Proceedings |  Articles published in Scimago's Q1 journals |  UoM Research Reports |  Other Articles authored by UoM staff |
Recent Submissions
item: Conference-Extended-Abstract
Sustainable spot treatment for Sri Lanka's highway curves
(Department of Civil Engineering, University of Moratuwa, 2026) Thenuwara, HV; Chandrathilaka, K
Sri Lanka records nearly 38,000 road crashes annually, causing over 3,000 deaths and 8,000 serious injuries, with losses equal to 3 to 5 percent of national gross domestic product (GDP). Roughly 45 percent of fatal and grievous crashes occur where excessive speed meets hazardous horizontal curves in the central highlands, yet existing safety measures rely mainly on driverbehaviour campaigns and civil works rather than pavement friction restoration. This study examines whether locally sourced aggregate can support High Friction Surface Treatment (HFST) as an affordable, low-carbon spot treatment for such curves, reducing dependence on imported bauxite and proprietary resins. Local quarry samples were tested against UK and AASHTO aggregate specifications, and three resurfacing options, hot-mix asphalt overlay, double bituminous surface treatment, and polymer-resin HFST, were compared using a tenyear Life-Cycle Assessment and Life-Cycle Cost Analysis. Quarry sources from Kandy and Anuradhapura met required friction and durability thresholds. HFST produced the lowest tenyear carbon footprint, despite a higher initial cost, and offered wet-weather crash reduction of 60–83% versus 15–25% for conventional treatment, with service life exceeding ten years. These results empirically indicate that domestically manufactured HFST, applied selectively at high-risk curves, offers a durable, economical, environmentally favourable safety solution for Sri Lanka's mountainous highway network, further warranting pilot-scale field trials on systemlevel
performance.
item: Conference-Extended-Abstract
Climate-informed spillway design for Horuwila Wewa under future rainfall uncertainty
(Department of Civil Engineering, University of Moratuwa, 2026) Hassan, MDR; Perera, C; Wijayaweera, N; Chandrathilaka, K
Intensity-Duration-Frequency (IDF) curves for water infrastructure are traditionally developed assuming climate stationarity. However, human-induced climate change has altered extreme rainfall patterns in recent decades, rendering historical curves untenable and raising global flood risk. Horuwila Wewa, an ancient reservoir in Anuradhapura with a catchment area of 26.4 km2 within Sri Lanka's Dry Zone tank cascade system, faces growing challenges managing extreme rainfall under future climate change. This study aims to quantify climate projection uncertainty in future extreme rainfall and assess its implications for Horuwila Wewa's spillway design. Using observed rainfall (1995–2024) and downscaled projections from three Coupled Model Intercomparison Project Phase 6 (CMIP6) general circulation models (GCMs) (CNRMCM6- 1, HadGEM3-GC31-LL, MRI-ESM2-0) under shared socioeconomic pathways (SSPs) SSP2-4.5 and SSP5-8.5, 50-year return-period IDF curves were developed for 2041–2060 and 2081–2100. Daily extremes were estimated using the Gumbel distribution and disaggregated into sub-daily intensities using regional temporal distributions. The resulting IDF curves were incorporated into an uncalibrated HEC-HMS model to simulate reservoir inflows and determine the spillway length required to maintain target peak-pool stage under a 0.8 m bundheight increase. Peak inflow varied from −13.1% to +57.8% relative to the 283.8 m³/s baseline, reflecting substantial inter-model uncertainty. The most severe scenario (MRI-ESM2- 0, SSP5-8.5, 2081–2100) required an 84% increase in spillway length. The results demonstrate that climate projection uncertainty can substantially influence spillway design requirements. Incorporating multiple GCMs and SSPs into climate-informed IDF analysis can provide a more robust basis for adapting reservoir infrastructure to future extreme rainfall.
item: Conference-Extended-Abstract
Quantifying reservoir capacity enhancement and spillway design under future climate scenarios in the Kattiyawa Wewa, Knuckles basin, Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2026) Rajapakse, RLHL; Ratnasooriya, H; Akhter, S; Chandrathilaka, K
This study assessed future climate impacts on Sri Lanka’s Kattiyawa Wewa Reservoir, located downstream of the Knuckles Basin. It quantified the reservoir capacity augmentation and spillway design upgrades required under those scenarios. Future daily precipitation projections from three Coupled Model Intercomparison Project Phase 6 (CMIP6) global climate models (GCMs) (CNRM-CM6-1, HadGEM-GC31-LL, and MRI-ESM2-0) under SSP2-4.5 and SSP5-8.5 scenarios were statistically downscaled to the watershed level for the 2041–2060 and 2081– 2100 periods using LARS-WG software. The downscaled daily data were disaggregated to subdaily durations using to develop Intensity-Duration-Frequency curves. These rainfall inputs were incorporated into the HEC-HMS hydrological model, configured with SCS Curve Number loss method and unit hydrograph transforms, to simulate design flood hydrographs and estimate critical peak discharges for various return periods. Results show peak discharges rising drastically, up to 1,378 m³/s under the HadGEM-GC31-LL SSP5-8.5 scenario by 2081– 2100, representing a 215% increase from baseline conditions. Using area–capacity curves derived from the non-dimensional relationship developed for small tanks in Sri Lanka, required storage enhancement ranges from 55% to over 200%, depending on the climatic scenario. Spillway capacity must be upgraded to 1,100–1,200 m³/s with concurrent storage expansion, or up to 1,380 m³/s without it. Existing infrastructure is shown to be inadequate under most scenarios. Adaptive strategies include reservoir capacity enhancement, combined with operational flexibility to manage variable inflows, preventing overtopping, reducing downstream flooding, and ensuring long-term dam safety.
item: Conference-Extended-Abstract
Assessing the influence of rainfall-intensity-dependent time of concentration on spillway design under future climate scenarios in the knuckles basin, Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2026) Rajapakse, RLHL; Gunasekara, NK; Zaman, ST; Chandrathilaka, K
Although conventional hydrological design treats time of concentration (Tc) as a static constant, Tc is inversely related to rainfall intensity, making its dynamic representation important under climate change. This study assesses how rainfall-intensity-dependent Tc affects spillway design under future climate scenarios in the Knuckles Basin, Sri Lanka. Future climate projections were obtained from three CMIP6 GCMs (CNRM-CM6-1, HadGEM3-GC31-LL, MRI-ESM2-0) under SSP2-4.5 and SSP5-8.5, statistically downscaled to watershed level for 2041–2060 and 2081–2100 using LARS-WG. The resulting daily rainfall series were then used to develop future Intensity-Duration-Frequency (IDF) curves, with daily rainfall values disaggregated using a regionally developed by Engr. Ponrajah. An existing rainfall intensity–Tc relationship, developed using Detrended Moving-Average Cross-Correlation Analysis (DMCA), was adopted to estimate rainfall-intensity-dependent Tc, and hydrological simulations were performed in HEC-HMS using the SCS Unit Hydrograph method. The dynamic Tc relationship was incorporated into design-storm simulations to evaluate hydrograph shape, peak discharge, and spillway response. Results demonstrate an inverse relationship between rainfall intensity and Tc, with Tc decreasing from approximately 2.5 to 1.0 hours as intensity increases from 25 to 45 mm/h. Projected peak discharge varied substantially across climate projections, ranging from 81.6 to 205.4 m³/s. MRI-ESM2-0 under SSP5-8.5 for 2081–2100 produced the highest projected peak, reaching 205.4 m³/s, approximately 2.5 times the baseline peak discharge of 82.2 m³/s. To convey this maximum inflow, the spillway design required an increase in crest length from 58 m to 80 m and crest elevation from 72 m to 73 m, which attenuated the reservoir peak discharge from a baseline of 525 m³/s to 179.6 m³/s. These findings highlight the importance of dynamic Tc and multimodel climate projections for climate-resilient spillway design.
item: Conference-Extended-Abstract
Evaluating the performance of GNSS RTK and UAV (drone) technologies under vrs mode in challenging environments
(Department of Civil Engineering, University of Moratuwa, 2026) Gallage, S; Hettiarachchi, C; Chandrathilaka, K
Reliable geospatial data acquisition in obstructed environments is important for engineering surveying, but buildings, vegetation, multipath, and operational restrictions can reduce positioning reliability. This field study compared Global Navigation Satellite System Real-Time Kinematic (GNSS RTK), an RTK-enabled unmanned aerial vehicle (UAV) using Virtual Reference Station (VRS) corrections, and handheld Simultaneous Localisation and Mapping (SLAM) across urban, forested, mixed-use, and semi-urban sites in Sri Lanka. Static GNSS and closed Total Station traverses established the reference coordinates. GNSS RTK was tested at all four sites, UAV RTK only in the urban corridor, and SLAM in the forested and mixeduse sites. Horizontal performance was assessed using root mean square error (RMSE), median, 95th percentile, maximum error, and availability. GNSS RTK RMSE values ranged from 0.064 to 0.121 m, UAV RTK recorded 0.106 m in the urban corridor, and SLAM recorded 0.160 m in the forest and 0.299 m in the mixed-use site. GNSS RTK gave the lowest errors where a stable FIX was available; UAV RTK provided rapid coverage, while SLAM maintained continuous mapping with higher drift-related error. Technology selection should therefore reflect required accuracy, coverage, access, and operating constraints.