Browsing by Author "Soysa, VAN"

Now showing 1 - 3 of 3

item: Conference-Extended-Abstract
Assessment of the stormwater drainage engineering in expressway design a hydrologic and hydrodynamic analysis of colombo-katunayake expressway using hydrodynamic modelling
(2009) Soysa, VAN; Wijesekera, NTS
Road designs need to forecast the hydrologic system performance in order to implement effective solutions for proper stormwater management. Field assessment and hydrologic analysis were carried out in Kalu Oya catchment (54.5 hn2) for the input data requirement of the hydrodynamic model. A satisfactory hydrodynamic model was developed using HEC-RAS with a calibration error of 55% and a verification error of 46%. Verified model was used to sensitivity analysis and management scenario modeling for achieving optimum expressway and hydrologic design.
item: Thesis-Abstract
Coastal and environmental impacts arising from major coastal infrastructure development projects
Soysa, VAN; Samarawickrama, SP; Hettiarachchi, SSL
Sri Lanka being an island state, strategically located in the Indian Ocean, has a high potential for the developments of its economy in the coastal zone. During the reason past, there have been major development projects undertaken by the Government of Sri Lanka including the developments of ports, tourism industry and urban development. At the same time, it must be noted and recognised that the coastal zones are environmentally very sensitive and have to be conserved in order for well-being of unique coastal eco-system, This conflict between development and conservation has raised major issues among the environmental protectionist. Such groups have raised concerns of the impacts of development project on the coastal zone. Although many coastal region development projects have been undertaken, hardly any project has been monitored to study its impact on the environment. In this respect, planned monitoring of Colombo South Harbour (CSH) project, one of the largest engineering projects to be undertaken in Sri Lanka, provided an excellent opportunity to study the impacts arising from appreciable disturbances to the seabed and neighbouring regions. The analysis of this monitoring, which is the major part of this research study identifies the extent of impact arising from mega coastal projects. Both CSH and associated Loading Out Point (LOP) at Wadduwa have therefore been considered, In addition, it focused on the Kirinda Fishery Harbour project, which failed in the first instances as well as after rehabilitation. The impact on vessels manoeuvring during extreme hazardous condition was investigated via the case study of Shimoda port Japan, undertaken by the researcher during a training programme at Port and Airport Research Institute, Japan. From this research study, it is concluded that no significant coastal environment impacts are raised due to CSH project as far as sea water quality, air quality and suspended particles levels are concerned. However, threshold values for noise levels were frequently exceeded at quarry site. Further, LOP at Wadduwa indicated severe erosion at northern sections, and significant accumulation at southern sections. Observed data and calculations revealed that with the beach nourishment, for duration of a month, still amount of over 900 m3 of volume for a stretch of 50 m along the coastline, eroded around 0+150 N to 0+500 N and the value decreases to 250 m3 around 0+750 N to 0+900 N. From the results of numerical simulations for drifting bodies at Shimoda port, specific locations were identified as the safest and most suitable locations to be developed for berth and moor purposes at Shimoda port minimizing the intensity and probability of collision hazard. It is expected that detailed research studies will high-light the extent of impacts on the coastal zone of large civil engineering projects which interact with coastal water. Such interaction includes dredging, reclamation, construction of major coastal works, and its impact on livelihood of the coastal community during and after construction. In the absence of detailed monitoring during and after construction, one would only speculate the long term impacts without cross comparison with prevalent condition away from projects.
item: Article-Abstract
Stormwater drainage in expressway design analysis of Colombo Katunayake expressway at Kalu Oya
Soysa, VAN; Wijesekera, NTS; Hydrologic analysis; Hydrodynamic Modelling; Sensitivity analysis
Flooding hasI been identified as the most costly and damaging natural hazards when lth magnitude and frequency is considered, assessment of stormwater drainage systems is very important to manage flooding. Most of the new infrastructure development projects such as (Instruction of expressways obstruct natural drainage paths. Therefore, when designing such projects, lie attention should be paid to identify potential impacts. Field assessment, hydrologic analysis, and hydrodynamic modelling play key roles in identifying the flow dynamics in case of engineering infrastructure developments such as roads, bridges or causeways. The present work describes the hiydrologic and hydrodynamic modelling case study of Colombo Katunayake Expressway (CKE) at Ill' intersection of Kalu Oya. A systematic field assessment, hydrologic analysis and a hydrodynamic modelling exercise was carried out. Data were collected through field work, agency visits, and illlitarature surveys. Hydrologic analysis was carried out to estimate the design discharge for different 'durn periods for both existing and future conditions incorporating rapid variation in land use mttern due to development activities. A hydrodynamic model was developed, calibrated, and irified. Design alternatives were considered through various possible scenarios modeled with a satisfactory hydrodynamic modelling having model calibration and verification errors of 55 % and 46 % respectively.