Browsing by Author "Manathunga, JMA"

Now showing 1 - 5 of 5

item: Thesis-Abstract
Comprehensive guideline for sustainable involuntary resettlement : special case study on problematic Tsunami resettlement site in Galle district
Senevirathna, AD; Manathunga, JMA
Resettlement has a long history in the world. According to the way of resettling, it can be categorized in to two. Depending on the method of resettlement it can be categorize in to voluntary and involuntary resettlement. Several Law enacted by parliament, guidelines and policies at the different occasions of resettlement history. In fact, there was large scale resettlement program in Srilanka after the Tsunami devastation in December 2004. For the post Tsunami recovery program, the National Housing Development Authority (NHDA), under the Ministry of Housing & Construction, formulated a detail guideline to be used by the prospective house builders in the disaster prone coastal belt in Sri Lanka. Apart from this, Nongovernmental organizations and international organizations prepared guidelines and policies regarding the resettlement program. However there are several policies and guidelines available for resettlement, it was not happening in effectively. As a result involuntary resettlement sites have become partially and completely abandoned. This may attributed to the prevailing social, environmental, socio economic problems. The main issue is whether in voluntary resettlement has been correctly address by the resettlement project plan. Most resettlement projects not correctly follow the available guidelines correctly. Beside some guidelines developed by the government bodies do not to address the real ground level situation. In this research, the prevailing environmental, social, socio economic and physical problems of in involuntary resettlement have been identified and suggestions have been made to enhance NHDA guideline in to a comprehensive and more practical guideline for sustainable resettlement by considering the ten years experience of Tsunami resettlement in Galle district.
item: Thesis-Abstract
Development of a drinking water quality index for dry zone of Sri Lanka : application to Kala-Oya basin
Jayaratne, LI; Manathunga, JMA; Athapaththu, BCL
Water Quality Indices have been developed to assess the suitability of water sources for its intended uses which give the status of water quality in water sources. Over past few decades, deterioration of water sources in Sri Lanka is getting critical. Ground water plays a significant role as a drinking water source in rural communities of dry zone while surface water is not that vital. In such circumstances, feasibility of use of water from traditional village irrigation tanks for drinking is utmost importance. To assess the surface water in dry zone, Drinking Water Quality Index was developed following four steps; (1) Selection of parameters considering their importance to the assessment study and availability of data. (2) Development of sub-indices by converting different units and rangers of water quality measurements for selected parameters into common scale, (3) Assigning weighting to the selected parameters considering their contribution to final index, (4) Aggregation of sub- indices and weightings using aggregation equations producing final index. Drinking Water Quality Index was then applied to Kala-oya basin in order to characterize the spatial and temporal variability of surface water quality in the basin. Kala-oya basin, located in the north-western dry zone of Sri Lanka is irrigational watershed which supplies water to agriculture, recreation and domestic purposes including drinking. Drinking Water Quality Index was calculated from ten physicochemical parameters; pH, Conductivity, Total Dissolved Solids, Turbidity, Hardness, Nitrate, Phosphate, Sulfate, Fluoride, Biochemical Oxygen Demand, Chemical Oxygen Demand, Total Coliform and Faecal Coliform periodically measured at 16 sampling sites in three reservoirs in Kala-oya basin; Kalawewa, Dambulu-oya and Bowathenna, from January to December 2014. The results revealed that Drinking Water Quality Index scores varied between 38 to 80 indicating deterioration of water quality. It was observed that surface water samples from 78% of sampling locations were categorized as ‘Marginal’ water quality. Results of remaining locations showed ‘Fair’ and ‘Poor’ water quality. In none of the locations, the score of the DWQI was determined as ‘Good’ or ‘Very Poor’. Water quality analysis done for assessing the level of treatment showed all the locations need advanced water treatment. The Drinking Water Quality Index shows an overall suitability of water bodies for drinking with level of treatments. Proposed Drinking Water Quality Index can be applied for watersheds in other parts of the country.
item: Thesis-Abstract
Development of flocculating paddles in mobile water treatment plants
(2014-07-11) Fernando, HCS; Manathunga, JMA
Water is precious for every living being. It covers almost 75% of the earth's surface, t Only about 3% of the water on earth exists as fresh-water and most of it is not easily available to men. Freshwater sources are polluted by activities of men, animals and by natural disasters. Water pollution is dominated by industrial and domestic wastes through channels and drains. Treating this water to meet standards of drinking quality is a huge task and a costly process. ^ Many countries face the problem of providing safe drinking water rapidly when faced with disaster situations like thousands of refugees as a result of civil disturbances, or natural disasters such as tsunami-related events, earthquakes, landslides, droughts or in an event of floods. The main issue is to construct water treatment plants which are heavy concrete structures in a shorter period of time in a limited land space. •The R & D section of the National Water Supply and Drainage Board (N.W.S.& D.B) has designed and fabricated a moveable water treatment plant using locally available materials and expertise within an affordable capital cost . Three of these mobile type water treatment plants have being installed in Pugoda, Mahiyangana and Allauwwa. This type of water treatment plants can dismantle into separate sections. They are fabricated steel tanks as middle stages of water treatment plant array. These sections can be transported to another place, re-assembled and re-located. The Pugoda plant has a mechanical flash mixer and three speed mechanical tapered flocculators. Flocculating is done by four paddle rotors rotated by geared motors in three speeds in three adjacent tanks. These paddle wheels (rotors) are mounted on a horizontal axis * inside the tank. The two ends of axel are sealed and supported by two end bearings housed beside the tank steel wall. This arrangement of the paddle wheels gives many operational and maintenance difficulties when dismantling the bearings and water seals. Very frequently chemically mixed water leaks through the water seals and bearings. This leads to reduce productivity by reducing bearing life, equipment safety and increasing down time, power requirement and operational cost. It needs a substantial quantity of water to remove the sludge in the bottom bed by washing them out. The objective of this special study is to study the ways and means of improving the present installation arrangements of flocculator paddle wheels and to propose an alternative arrangement eliminating above operational difficulties. Objective is to find an efficient alternative mechanical flocculator system to be used in package-type water treatment plants. This report discusses about conventional water treatment arrangement, a brief study of floe forming phenomena, specification of the mobile water treatment plant, flocculator types and other arrangement types of mechanical flocculators used elsewhere in the world. The report includes theoretical aspects of power requirement for rotating paddles. The study also proposes a vertical arrangement of flocculating. This is by fabricating frame and a plate to mount the gear box and motor. This frame is fitted on to the top frame of the tank. The axes of the paddle wheel is supported by two bearings, one is top of the channel section and the other is submerged in the water. The housing shall be fixed to fabricated plate to bottom of tank. The bearing shall be water resistant type and fully water tight by seals. The advantages expected from this arrangement are to prevent water leaks, long life of seals, bearings and couplings and to reduce operational and maintenance difficulties thus reducing operational costs and reducing the amount of sludge washing water.
item: Conference-Abstract
Framework for sustainable management and utilization of wetland resources: a case study of Madinnagoda marsh
(Department of Civil Engineering, University of Moratuwa, 2021-11) Pathirana, HA; Manathunga, JMA; Hettiarachchi, P
Wetlands, the lands of areas saturated with water throughout the year or seasonally, are the caretakers of the earth due to the reason that they provide an unparalleled range of environmental benefits. Wetlands actively contribute to making this world liveable. However, the sad truth is that wetland habitats continue to be lost entirely or progressively degraded at an alarming rate, regardless of the multitude of benefits that the wetlands provide. Wetlands are badly subjected to environmental pressures as a direct consequence of anthropogenic activities, which are the driving forces that lead to ecosystems damage. In turn, the state of such ecosystem changes subsequently impact the natural environment as well as the society. Madinnagoda wetland is one such valued ecosystem embracing the sad truth of wetland degradation that had occurred persistently during the past few decades. Close proximity to a highly urbanized area thus receiving a high value on its land extent, the severe shortage of land for economic development in the city, availability of a large extent of land in this wetland, and its location in the heart of Colombo make this wetland becoming a populated and rapidly developing area of Colombo District attracting more urban life. The exploitation of this wetland resource has vast negative consequences if this trend continues. Based on such concerns, issues of sustainability have been in focus lately, with Colombo’s wetlands declared as Ramsar sites. The necessity of a proper mechanism has arisen to maintain these ecosystems as they were. Therefore, this research was carried out to develop a framework for sustainable management and utilization of wetland resources at Madinnagoda Marsh. The DPSIR framework was used for the study, one of the best tools recognized to analyse environmental problems and devise sustainable solutions. However, it has been subjected to critiques in the literature. Although the confusion between the terminologies is identified as the main reason for such criticism, the framework has been subjected to many evolutions to give the best output. After analysing the Madinnagoda wetland with nested DAPSI(E1 and S1)R(M1) framework, a development plan was proposed, and its capability of sustainably managing and utilizing the wetland resources was measured as per the level to which its strategies fulfil the 17 Sustainable Development Goals. For this purpose, scorecards were developed under each weighted sustainable goal to assign the development plan with scores, and then, a methodology was developed to calculate the sustainability score. Finally, a wetland rating system was proposed to decide the level of sustainability of the Madinnagoda Marsh. Since there is no ongoing development plan for Madinnagoda Marsh targeting its sustainable development, this research study leaves the validation phase as a future work - though a hypothetical situation is proposed to ensure that the procedure and the validity of the framework that have been proposed is well demonstrated. Therefore, it is possible to modify the proposed development plan, proposed framework, and rating system to comply with the future settings aiming at achieving sustainable utilization of wetland resources. Even so, the beneficiaries of the wetland resources and the public at large should make sensible decisions to determine how they are going to sustainably manage and conserve this valued ecosystem.
item: Conference-Abstract
Water footprint assessment for a proposed integrated solid waste management facility: an application to Beruwala UC
(Department of Civil Engineering, University of Moratuwa, 2021-11) Bamunuarachchi, BASN; Manathunga, JMA; Hettiarachchi, P
Water can be considered one of the essential resources to sustain life on earth. For human use, reliable access to clean and affordable water is regarded as one of the humanitarian goals. It is alarming to note that humans consume freshwater resources at a rapid rate, which is unarguably considered as unsustainable. Hence, the global concern is focused on more effective means to protect and conserve freshwater resources for all the current and future needs. During their entire life cycle, buildings and civil engineering structures consume large amounts of freshwater, leading to various strategies adopted for conserving it. However, most of these strategies are only used at the facility operating stage, while the water utilized in the construction phase is grossly overlooked and ignored. This research investigates the significance of preoperational embodied water through analysing a case study of a proposed integrated solid waste management (ISWM) facility at Beruwala UC and attempts to establish the importance of innovative and sustainable design practices. To compute water embodied in the construction materials, five types of materials, which are soil/rockfill, brick, concrete, steel, and ceramic tiles, were considered. To compute the inherent embodied water content, the quantities of building material extracted from the Bill of Quantities were multiplied by the embodied water coefficients of each material from past literature. Operational water usage was calculated considering all the activities at the period of operation of the ISWM facility. After that, it was converted to a 30-year life cycle period. To determine the significance of embodied water, it was compared with water consumed during the operational period. The study determined the pre-operational embodied water as 7 kL/m2. This represents 22% of operational demand for water, considering a life cycle of 30 years. Also, few strategies to reduce water usage in pre-operational and operational stages were identified in this research. The study indicates that the water embodied in producing the construction materials is significantly greater than the actual water usage during construction. Sustainable strategies for construction, in general, and sustainable on-site water use, in particular, are relatively low priority sectors in the construction industry. However, with the increasing scarcity of freshwater resources, strategies should be implemented to reduce water usage in the construction industry. Choice of materials and their water efficiency plays a significant role in the total embodied water density of any construction. In practice, determination of total embodied water density ignores specific components of buildings, however, proper attention should be paid to each element in the design to ensure sustainable practices for saving freshwater sources.