Research Papers - Department of Civil Engineering

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End date: 2025Subject: search.filters.subject.Sri Lanka

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    PublicationOpen Access
    Profiling Microplastic Pollution in Surface Water Bodies in the Most Urbanized City of Sri Lanka and Its Suburbs to Understand the Underlying Factors
    (Springer, Cham, 2023-02-23) Bandara, R. M. L. S.; Perera, M. D. D.; Gomes, Pattiyage I. A.; Yan, Xu-Feng
    This study investigated the microplastic pollution of surface waters in and around the most populated and urbanized city in Sri Lanka from 2019 to 2022. The sampling regime was designed to cover the rainfall-driven hydrology and varying levels of urbanization approximated by the built area fraction. Mass and particle concentrations of microplastics ranged from undetected to 0.01 g/L (average ± standard deviation: 0.00464 ± 0.00528 g/L) and from 2 to 36 particles/L (5.3 ± 6.9), respectively. The highest microplastic pollution was observed in the lake; however, in many cases it was without a statistically significant (P < 0.05) difference with canals. Concentrations in the dry state (i.e., at least 30 days after no rainfall) were about 1.5 times more than the wet state (i.e., at least 50 mm/day rainfall for 10 days) in the lake and in the semi-urban canal, but again, the differences were not significant; however, in urban canals, the concentrations were similar in both states. Over 80% of the microplastics were fibre and fragments. Mass concentrations of microplastics showed moderately positive (Pearson’s r > 0.6) correlations with the built area fraction of the contributing catchment in both states but was significant (P < 0.1) only in the dry state. In the case of particle concentrations, none showed even a weak correlation. The independence of microplastic content against built area fraction and rainfall, as well as twice the concentrations found in point source inputs against the surface waters, gave the following insights. Microplastic content in our study area was governed mostly by the modified catchment hydrology spearheaded by stormwater drainages (some cases trans-catchment) and diffusion factors such as non-residential population.
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    PublicationOpen Access
    Spatio-Temporal Rainfall Variability and Concentration over Sri Lanka
    (Hindawi, 2022-09-28) Pawar, U; Karunathilaka, P; Rathnayake, U
    Changes in precipitation patterns significantly affect flood and drought hazard management and water resources at local to regional scales. Therefore, the main motivation behind this paper is to examine the spatial and temporal rainfall variability over Sri Lanka by Standardized Rainfall Anomaly Index (SRAI) and Precipitation Concentration Index (PCI) from 1990 to 2019. The Mann–Kendall (MK) trend test and Sen’s slope (SS) were utilized to assess the trend in the precipitation concentration based on PCI. The Inverse Distance Weighting (IDW) interpolation method was incorporated to measure spatial distribution. Precipitation variability analysis showed that seasonal variations are more than those of annual variations. In addition, wet, normal, and dry years were identified over Sri Lanka using SRAI. The maximum SRAI (2.27) was observed for the year 2014 for the last 30 years (1990–2019), which shows the extremely wet year of Sri Lanka. The annual and seasonal PCI analysis showed moderate to irregular rainfall distribution except for the Jaffna and Ratnapura areas (annual scale-positive changes in Katugastota for 21.39% and Wellawaya for 17.6%; seasonal scale-Vavuniya for 33.64%, Trincomalee for 31.26%, and Batticaloa for 18.79% in SWMS). The MK test, SS-test, and percent change analyses reveal that rainfall distribution and concentration change do not show a significant positive or negative change in rainfall pattern in Sri Lanka, despite a few areas which experienced significant positive changes. Therefore, this study suggests that the rainfall in Sri Lanka follows the normal trend of precipitation with variations observed both annually and seasonally.
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    PublicationOpen Access
    Global warming potential of English brick manufacturing in Sri Lanka: A cradle to gate analysis
    (IEEE, 2021-07-27) Herath, I; Karunaratne, S; Dharmarathna, D
    Clay bricks are one of the most commonly used walling materials in Sri Lanka. The brick manufacturing process poses a notable impact on the environment. Clay excavation leads to resource depletion while diesel fuel utilized for excavation and clay transportation pollutes the air. Additionally, tree cutting for wood fuel contributes to deforestation whilst wood burning promotes air pollution. Thus, this research aimed to quantify the global warming potential due to English brick manufacturing using cradle to gate Life Cycle Assessment (LCA) approach. The functional unit used was one-meter square of the brick wall area. Data collection, analysis and interpretation of results were done by the ISO 14044/14040 standards. Primary life cycle inventory data was gathered via brick kiln owners and workers. The LCA assembly was modelled using the ‘OpenLCA’ software. Three product systems were defined according to the brick bond types and wall thicknesses. The global warming potential related to brick production was assessed using the ‘GWP 100a’ method. Clay excavation, clay transportation and wood chamber firing emerged as emission hotspots. The study revealed that the global warming potential of 225mm brick wall and 115mm brick wall as 11.9 and 5.9 kg CO2-eq/m 2 , respectively. Through this study, local clay brick industry can be driven to improve the overall sustainability of the brick manufacturing sector.
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    PublicationOpen Access
    Forecasting Electricity Power Generation of Pawan Danavi Wind Farm, Sri Lanka, Using Gene Expression Programming
    (Hindawi, 2022-05) Herath, D; Jayasinghe, J.M.J.W; Rathnayake, U
    is paper presents the development of a wind power forecasting model based on gene expression programming (GEP) for one of the major wind farms in Sri Lanka, Pawan Danavi. With the ever-increasing demand for renewable power generation, Sri Lanka has started harnessing electricity from wind power. ough the initial establishment cost of wind farms is high, the analyses clearly showcased the economic sustainability of wind power generation in long term. In this context, forecasting the wind power generation at Sri Lankan wind farms is important in many ways. However, limited research has been carried out in Sri Lanka to predict the wind power generation against the changing climate. erefore, to overcome this research gap, a model was developed to forecast wind power generation against two climatic factors, viz. on-site wind speed and ambient temperature. e results showcased the robustness and accuracy of the proposed GEP-based forecasting model (with R2 0.92, index of agreement 0.98, and RMSE 259 kW). Moreover, the results of the study were compared against three dierent forecasting models and found comparable in terms of the model accuracy. e GEP-based model is advantageous over machine learning techniques due to its capability in deriving a mathematical expression. As an acceptable relationship was found between wind power generation and climatic factors, the proposed model facilitates the future projection of wind power generations with forecasted climatic factors. ough the application of GEP in the eld of wind power generation is reported in a few research publications, this is the rst research in which GEP is employed to model the power generation with respect to weather indices. e proposed prediction model is advantageous than machine learning models as the relationship between the wind power and the weather indices can be expressed.
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    PublicationOpen Access
    Multidecadal Land Use Patterns and Land Surface Temperature Variation in Sri Lanka
    (Hindawi, 2022-05-16) Samarasinghe, T; Rathnayake, U; Makumbura, R. K
    Agricultural land conversion due to urbanization, industrialization, and many other factors is one of the significant concerns to food production. Therefore, analyzing the temporal and spatial variation of agricultural lands is an emerging topic in the research world. However, an agrarian country like Sri Lanka was given weaker attention to the temporal and spatial variation of the land use, including the agricultural lands. This study presents an extended analysis of temporal and spatial variation of land use patterns in Sri Lanka, specifically looking at the agricultural land conversion and land surface temperature (LST) change. Remote sensing techniques and geographic information system (GIS) were used for the presented work. The satellite images from three Landsat’s were analyzed for 2000, 2010, and 2020 to identify the potential land use conversions. In addition, LSTs were extracted for the same period. Significant and continuous increases can be seen in the agricultural lands from 33.94% (of total area) in 2000 to 43.2% in 2020. In contrast, the forest areas showcase a relative decrease from 38.51% to 33.82% (of total area) during the analyzed period. In addition, the rate of conversion from agriculture to settlements is higher in the latter decade (2010–2020) compared to the earlier decade (2000–2010). Only general conclusions were drafted based on the LSTs results as they were not extracted in the same months of the year due to high cloud cover. Therefore, the results and conclusions of this study can be effectively used to improve the land use policies in Sri Lanka and lead to a sustainable land use culture.
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    PublicationOpen Access
    Evaluation of Satellite Rainfall Products over the Mahaweli River Basin in Sri Lanka
    (Hindawi, 2022-04) Perera, H; Fernando, S; Gunathilake, M. B; Sirisena, J; Rathnayake, U
    e availability of accurate spatiotemporal rainfall data is of utmost importance for reliable predictions from hydroclimatological studies. Challenges and limitations faced due to the absence of dense rain gauge (RG) networks are seen especially in the developing countries. erefore, alternative rainfall measurements such as satellite rainfall products (SRPs) are used when RG networks are scarce or completely do not exist. Noteworthy, rainfall data retrieved from satellites also possess several uncertainties. Hence, these SRPs should essentially be validated beforehand. e Mahaweli River Basin (MRB), the largest river basin in Sri Lanka, is the heart of the country’s water resources contributing to a signi cant share of the hydropower production and agricultural sector. Given the importance of the MRB, this study explored the suitability of SRPs as an alternative for RG data for the basin. Daily rainfall data of six types of SRPs were extracted at 14 locations within the MRB. ereafter, statistical analysis was carried out using continuous and categorical evaluation indices to evaluate the accuracy of SRPs. Nonparametric tests, including the Mann-Kendall and Sen’s slope estimator tests, were used to detect the possibility of trends and the magnitude, respectively. Integrated MultisatellitE Retrievals for Global Precipitation Measurement (IMERG) outperformed among all SRPs, while Precipitation Estimation from Remotely Sensed Information using Arti cial Neural Networks (PERSIANN) products showed dire performances. However, IMERG also demonstrated underestimations when compared to RG data. Trend analysis results showcased that the IMERG product agreed more with RG data on monthly and annual time scales while Tropical Rainfall Measurement Mission Multisatellite Precipitation Analysis–3B42 (TRMM-3B42) agreed more on the seasonal scale. Overall, IMERG turned out to be the best alternative among the SRPs analyzed for MRB. However, it was clear that these products possess signi cant errors which cannot be ignored when using them in hydrological applications. e results of the study will be valuable for many parties including river basin authorities, agriculturists, meteorologists, hydrologists, and many other stakeholders.
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    PublicationEmbargo
    Pavement maintenance management system for low volume roads in Sri Lanka
    (IEEE, 2019-07-03) Perera, M. Y. I; Pasindu, H. R; Sandamal, R. M. K
    In Sri Lanka there are about 150,000 km of roads and among those about 75% are considered as rural low volume roads [1]. These roads are essential in community development, transport of people, goods and services in the rural areas. Most of these low volume roads would be actively contributing to our country's economy and wellbeing by distributing the produces from rural areas to urban areas. Limited funding, subjective and ad-hoc maintenance decision making has resulted in suboptimal maintenance level for these road networks. There is no proper maintenance system available in Sri Lanka as in the foreign countries. Lack of technical expertise and shortage of human resources, equipment and funds to carryout detailed data collection and analysis makes use of existing Pavement Management Systems difficult for local road agencies. The study will be focused on developing an asset management system to manage rural and provincial road networks in Sri Lanka.
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    PublicationOpen Access
    Self-reported habitual practices and perceptions of young drivers in Sri Lanka
    (Sri Lanka Society of Transport and Logistics, 2021-03) Amarasingha, N; Firdhaws, H. M. M
    Crashes on the road have become a significant socio-economic problem. Younger generations, who have lesser experience in driving, are at greater risks of facing road accidents. It is therefore important to identify driving practices and perceptions of young and inexperienced drivers at an early phase of exposure so that factors that improve safe driving can be identified. This study analysed 400 young and inexperienced drivers’ self-reported habitual practices and perceptions based on a questionnaire survey. The questionnaire focused on supervision of early driving, limitation made by parents, accident and traffic offenses by these youngsters as drivers as well as other habitual driving practices. Analyses were done using reliability statistics, inter-item correlation, likelihood ratio tests, and parameter estimates. The highest inter-item correlation value was 0.467 for the pair of overtaking vehicles in restricted areas and taking the chance to speed and run a yellow light when it is about to change to red. Driving after alcohol consumption, mobile phone usage, taking an illegal U-turn at restricted areas, non-use of signals when changing lanes and overtaking a slow driver from the left side were influenced non-use of seat-belts by young drivers. These habitual practices while driving highlighted the importance of early intervention to improve road safety. In conclusion, there is always one or more habitual driving practices that have affect the other driving habits of a young driver.
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    PublicationOpen Access
    Risk Factors of Motorcycle Crashes in Sri Lanka
    (University of Moratuwa, 2016) Amarasingha, N
    The use of motorcycles has become a passion or even a way of life in many South Asian countries including Sri Lanka, for commuting to work or transporting goods, as they are easy to use and to cover short distances. In these countries, ownership and use of motorcycles and other two-wheelers are generally relatively high. Compared to drivers of other vehicles, motorcyclists are vulnerable road users as they often share the traffic space with fast-moving vehicles, they are less visible, and also they lack protection in the case of a crash. All Sri Lankan regulations for motor vehicles are applicable to motorcycles. The owners are required to register their vehicles and also obtain driving licences to operate motorcycles. They also are required to obtain annual revenue licenses. Motorcycles are popular among middle income and low income people in Sri Lanka and mainly used to commute to work and also used to transport goods, as well as for recreational purposes. The most common vehicles on Sri Lankan roads are motorcycles and the number of motorcycles is more than three times the number of the second most popular vehicle, namely the three-wheeler. The percentage of increase of registered motorcycles in Sri Lanka from year 2003 to 2012, was 152% [1]. As the number of motorcycles increase, so does the probability of their being involved in motor vehicle crashes.
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    PublicationOpen Access
    Characteristics of Railway-Roadway Level Crossings at Coastal Railway Line in Sri Lanka
    (KDU IRC 2017, 2017) Amarasingha, N; Gunathilaka, O. H. D. C; Ragulan, K; Aravinda, M. P. N; Fernando, W. S. H. R
    Rail transportation is a safe, efficient, continuously operating sustainable transportation mode, in all-weather conditions, and light conditions. Along with these advantages, the role of rail transport has become increasingly important. Therefore, it is important to investigate the characteristics of the railway-roadway level crossings in Sri Lanka. Railway-roadway level crossings at coastal railway line from Aluthgama to Ambalangoda were visited to collect the roadway, railway, traffic, environmental, and crash data. Out of 51 crossings that observed in this study, about 94.1% of railway-roadway level crossings were facilitated with active safety measures. About 7.0% of railway-roadway level crossings were without gates and among them 33.3% of crossings were facilitated with passive safety measures and other crossings were under unsafe conditions. Several problems related to railway-roadway level crossing were identified. The collected data could be utilized to develop various statistical models for identifying relationships between the number of crashes and level crossing characteristics. It could be used to identify potential highcrash prone railway-roadway crossings and key factors which increase the number of crashes.