Browsing by Author "Harshani, HMD"

Now showing 1 - 3 of 3

item: Conference-Extended-Abstract
Application of stormwater management modeling for ungauged watersheds in urban areas - a case study of the Matara municipal council area.
(2010) Harshani, HMD; Wijesekera, NTS
This paper is based on the studies of existing problems with regards to the storm water in Walgama area Matara Municipal Council and providing Engineering and Management options through a mathematical model EPA SWMM5. Several field visits were conducted to the study area in order to investigate the existing problems and collect the field data for model development. Model was verified with field survey data and the parameters observed \'odes and canal parameters were varied to identify' influence on output using most sensitive parameters, engineering options were proposed for storm water problems.
item:
Evaluation of cover soil properties of solid waste dumpsites in Colombo District, Sri Lanka
Harshani, HMD; Nawagamuwa, UP; Senanayake, A;
Landfill cover soils have to serve multiple purposes such as operational safety, environmental protection, recultivation and integration of the sites into the landscape. Cover soil properties must therefore be defined with respect to the thickness, bulk density, air permeability and the available field capacity. The primary objective of this study is to examine the cover soil properties of three selected landfill sites (dumpsites) in Sri Lanka in order to propose suitable cover soil properties for similar applications in future dumpsites. Soil samples were obtained from three landfill sites in and around the city of Colombo. Laboratory tests to establish compaction characteristics, air permeability, particle size distribution and Atterberg limits were performed to assess the suitability as landfill cover soils. The study showed that landfill covers with well graded soils comply with the dry density and air permeability values, as per the guidelines. In the absence of proper gas venting facilities, it is essential to study the permeability properties of the cover soil. All three landfill sites tested need to be retrofitted with leachate and gas collecting systems that meet the standards stipulated in the guidelines.
item: Article-Abstract
Stormwater management modelling for ungauged watershed in Matara municipality
Harshani, HMD; Wijesekera, NTS
Most urban areas are having flood problems due to human activities. It is not easy to model urban watersheds since very often they are ungauged. This paper describes the modelling of an ungauged watershed in the Matara Municipal Council Area of Southern Sri Lanka using the free SWMM5 model of the EPA. Several field visits were conducted to capture the model parameters and flood scenario for model development and calibration. The watershed delineation was done using 1:10,000 topographic maps and canal slopes etc were determined using the elevation data of these maps. This watershed with an area of 1.12 km2 was modelled and calibration was done for the order of magnitude of the outputs. The model shows reasonable results with the actual conditions in the absence of gauge data This work demonstrates that urban stormwater model SWMM5 can be used in Matara Municipal Council area to a satisfactory level with adequate field data collection. However, for accurate results, it is necessary to suitably gauge the stream flows and carry out field and engineering surveys for the measurement of physical parameters. The model demonstrated the capability to identify engineering and stormwater management options. Model outputs revealed that cleaning of canals was one option for reducing the flooding at nodes. For the considered storm, a reduction of canal roughness from 0.2 to 0.015 reduced the flood peak by 56% and no flood is happening after introducing a rectangular detention unit which is having 200m2 floor area.