Master of Engineering in Environmental Water Resources Engineering and Management

Permanent URI for this collectionhttp://192.248.9.226/handle/123/16122

Browse

Browsing Master of Engineering in Environmental Water Resources Engineering and Management by Subject "DROUGHT MITIGATION-SRI LANKA"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    item: Thesis-Abstract
    Drought mitigation using rainwater harvesting in the dry zone of Sri Lanka
    Kumari, DMCS; Wickramasuriya, SS
    The government of Sri Lanka proposed to provide safe drinking water to all by 2025. However, this proposal is becoming a challenging task due to depletion and pollution of water resources combined with a growing demand and conflict among users. On the other hand, pipe borne water to all households is becoming costly due to the high level of investment required and increased operation & maintenance cost. Due to this situation, a large percentage of the both urban and rural population would be deprived of any form of safe drinking water. Therefore it becomes nationally important to look for low cost options which could be managed and afforded by the communities themselves. A rainwater based water supply system is an alternative option to solve this problem./ The objective of this research work is to investigate the more suitable storage volume required for rooftop rainwater harvesting system and determine the probability of success of practicing rainwater harvesting for domestic use in the dry zone of Sri Lanka./ The analysis uses thirty years of daily rainfall data (1968-1998) from Puttalam, Hambantota and Anuradhapura districts in the dry zone of Sri Lanka. The results show that the probability of success of a rainwater harvesting system shows a bimodal pattern during the year./ It has been found that the more suitable tank capacity required is 5 m3 corresponding to a roof area between 75m2 to 100 m2. Such a system can provide 120 liters per capita per day to a household of five persons and give an overall probability of success of approximately 30%. At 300 liters per day per household (ie. 50% of demand), the probability of success improves significantly to 50%.Thus rainwater harvesting can be a valuable tool of drought mitigation within the dry zone. The probability of success of a system varies throughout the year due to the seasonal variation of rainfall. In particular, during the period February to March and June to September a rainwater harvesting system alone will not be able to meet the required demand. The percentage saving of monthly water bills for urban schemes can vary from 25% - 33% considering the subsidy given by NWS & DB, and for consumers in rural schemes the amounts are 25% - 35%. These rainwater harvesting systems utilize 5 m3- 7.5 m3 tank capacities with 75 m2 - 100 m2 roof areas.
  • Thumbnail Image
    item: Thesis-Abstract
    Improved water conservation practices using rain water harvesting in the wet and intermediate zones of Sri Lanka
    Ranasinghe, RKWK; Wickramasuriya, SS
    Fresh water is a limited and precious resource that is often taken for granted. However many areas of the developing world suffer a lack of safe water. Therefore, water bome diseases account for an estimated 80% of all illnesses in developing countries. In addition, millions of women and children walk several kilometers every day just to fetch a minimum quantity of water for their families. Furthermore, the Sri Lankan government also faces many problems in finding safe water sources to meet the growing water needs of the entire population. Roof rainwater harvesting is the only feasible option in some parts of the country, to deal with this issue to a certain extent where no other water sources are available./ The research is targeted to study the water conservation practices using Rainwater Harvesting in the wet and intermediate zones of Sri Lanka. To analyze performance of a selected roof rainwater harvesting system, thirty years (1968-1998) of daily rainfall data from Galle, Rathnapura, and Kurunegala districts have been used. The roof sizes considered were 50 m2,75 m2, 100 m2 & 200 m2 and tank capacities considered were 1 m3, 2 m3, 5 m3 & 7.5 m3 for family size of five members. The daily water demand is taken as 120 liters per capita per day./ The results show that there is a 79% probability of success in the Galle district for supplying 300 liters of water per day per family (i.e. 50% demand fulfillment) by using a 5 m3 tank with a roof catchment area of 75 m2. The equivalent result for Rathnapura is 93% while for Kurunegala it is approximately 71%. Hence, the results clearly show that rainwater harvesting is an excellent alternative option for the partial fulfillment (50%) of daily domestic water demand within the wet and intermediate zones of Sri Lanka./ Finally, it can be concluded that roof rainwater harvesting is a very promising alternative solution for increasing water demand of the country. However, the research also shows that during a few months in the year, domestic users will be unable to survive comfortably only with rainwater harvesting.