Planning and Design of Roofwater Harvesting System

摘要

Water is the most widely distributed substance on our planet and it plays a vital role in both environment and human life. Global freshwater consumption rose six-fold between 2000-2010, more than twice the rate of population growth. According to United Nations, if the present trend continues, two out of every three people on earth will live in water stressed condition that is whose consumption exceeds 10% of total supply. Keeping in the view the effective use of rainwater, present study is conductedat College of Technology, G.B.P.U.A.T, Pantnagar, Uttarakhand, to test the feasibility of rainwater harvesting through roof-top of buildings. The present study is undertaken with the objective to design and cost estimation of rainwater harvesting systemto harvest the rain water from roofs of buildings. The rainfall data of last 49 years is analyzed to determine the probability of occurrence. The optimum size of tank is selected based on the water budgeting analysis of weekly rainfall data of monsoon season. The study reveal that one surface tank of 81 m3 (6m x 6m x 2.25m) size each for four hostels and four surface tank of 100 m~3 (8m x 5m x 2.5m) size are proposed for college buildings. The cost of construction of tank of size 100 m~3 is estimated tobe Rs 1,84,607 and of size 81 m3 is Rs 1,61,683. The total system cost is estimated to be Rs 69,24,660 including cost of guttering, conveyance, distribution of water and maintenance of the system till the end of the life of system (25 years). The B-C ratio and Pay-back period for college building, hostel building and for both are found to be 0.42, 1.75 and 1.01, and 60 years, 15 years and 25 years, respectively.