Browsing by Author "Gomes, P.I.A."

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Deflectors to introduce heterogeneity to canals
(Faculty of Graduate Studies and Research, 2017-01-26) Gomes, P.I.A.; Kumara, G. H. V. S.; Wijethilaka, M. A. D. K.; Randima, W. A. H.
Canals are manmade lotic water systems constructed for flood control, navigation, irrigation, etc. In general, canals are eco-hydrologically homogeneous. As such, a canal might have the same prismatic cross section and an even bed profile along its course. Such characteristics do not support rich biota, something a sustainable society expects. Several past studies have attributed heterogeneity to be an important factor for a healthy stream. In this study the deflectors were used to introduce the heterogeneity in canals. In tandem studying flow complexity by deflectors, their role with respect to sediment (sand) and seed transport, and fisheries were also studied. The model canal's (laboratory flume) homogenous velocity of 0.4 m/s changed to a range of values from 0.1 to 0.7 m/s after placing deflectors. Similarly, water depth changed from a uniform 30 mm to a range from 20 mm to 70 mm. This resulted in formation of flow patches similar to flow patches formed by meso-scale physical habitats such as pools and riffles. Sediment deposition was patchy and seemed to be stable as only a minor bedload movement was observed for prolonged durations. This meant it is possible to achieve a quasi-equilibrium state in field canals where upstream brings sediments. Seed trapping was weak for floating type seeds, whereas non-floating seeds managed to get deposited with sediment. Fishes quickly migrated to the pool like areas that resulted from deflectors. The results suggested the role of deflectors in transforming a homogenous channel to heterogeneous channel that has the potential to have rich biota which is essential in ecological rehabilitation works.
Open Access
Health, safety, and environmental impacts of road infrastructure projects in Sri Lanka; Impact analysis on ongoing and temporarily suspended road works
(Sri Lanka Institute of Information Technology, 2023-03-25) Kariyawasam, D.D.S.A.; Gomes, P.I.A.
Road networks are considered to be the primary mode of transport in Sri Lanka. Road infrastructure plays an important role in the country’s economy. The work environment of construction projects is generally considered one of the most dangerous places for work. The current economic recession faced by Sri Lanka has led to the temporary suspension of road works. The aim of this study is to identify the main types of health, safety, and environmental issues that occur in the construction of different ongoing and suspended road infrastructure projects in Sri Lanka. Questionnaire surveys, discussions, and site observations were carried out to collect data from road projects of different classes. Data analysis was done using the SPSS (Version 28) statistical software. The findings of the research indicated that vehicle collisions were the most common type of occupational accident faced in road construction in Sri Lanka. The fatality rate caused due to poor health and safety management of road construction works was compared with the construction of buildings and other developing countries. The results obtained from the study also identified that negligence was the main factor that influenced low safety standards on-site, which in turn impacted the performance of the construction project. Measures taken by construction companies of different grades to improve health and safety standards were also studied in the research. It was also evident that suspended road projects had an adverse effect on the environment, as it was seen that these sites possessed a loss in diversity, high chances of sediment erosion, and a rise in mosquito breeding locations. The findings of this research highlight the need of prioritizing health and safety in road projects and also enable construction companies to handle construction work in a way that minimizes environmental damage occurs.
Open Access
Microplastic Content in Non-Point Source And Point Sources of Colombo And Suburbs – Experimental Study on the Impact of Seasonal Variation
(Sri Lanka Institute of Information Technology, 2023-03-25) Ariyawansha, R.B.V.K.; Gomes, P.I.A.
Microplastics, which can enter aquatic environments through various sources, are small plastic pieces that are less than 5 mm in length. There are two types: primary and secondary microplastics. Sri Lanka has limited studies on microplastics in inland water bodies, so this research aims to quantify the levels of microplastic pollution in Colombo's surface waters in a spatiotemporal manner. Samples were taken from Beira Lake, Dutch canal network, Talangama canal, in wet and dry seasons. Microplastic concentrations were determined using NOAA guidelines and an optical microscope. Statistical analysis was performed using IBM SPSS version 21, including One-way Anova and Pearson correlations to identify significant differences and correlations. The study found that Dutch Canal had the highest average microplastic concentration of 12.7 mg/L during the wet season, and the lowest of 4.2 mg/L during the dry season. Both Dutch Canal and Talangama canal showed significantly higher microplastic concentrations during the wet season than the dry season, while the opposite was found in Beira Lake. The statistical analysis showed significant differences between microplastic concentrations in wet and dry seasons in all three water bodies. The microplastic levels in Beira Lake were higher on the surface water during the dry season (4.32 mg/L) and wet season (13.77 mg/L) compared to point sources (4.05 mg/L and 11.68 mg/L, respectively). Furthermore, Dutch canal's point sources showed higher during the dry season (8.47 mg/L) than the wet season (11.51 mg/L) and concentration of microplastics on the surface water was higher during the wet season (5.73 mg/L) than the dry season (7.16 mg/L). Talangama canal had similar patterns to Beira Lake. The study found microplastic contamination in urban and semi-urban surface waters at levels comparable to some industrialized countries, highlighting a concerning issue.