Author : Arthi .T 1
Date of Publication :29th November 2017
Abstract: Drainage is removal of undesirable excess water from a region; crop land, city streets, dwelling place, playground, airport etc. The drainage need is expressed in terms of drainage coefficient. Drainage coefficient is expressed as the depth in centimetre of water drained off from a given area in 24 hours. Daily rainfall data was analysed to obtain one to four consecutive days maximum rainfall. One to four consecutive days maximum rainfall data were arranged in descending order. Accordingly ranks are given for each year 1991 to 2014. Then by lognormal, Weibull and Gumbel distributions probabilities corresponding to maximum rainfall were found out. Excepted values for one to four consecutive days were estimated by three most widely used probability functions namely Gumbel, lognormal and extreme value type-III distribution. One to four consecutive days rainfall valves were computed for R.I of 5,10,15 and 20 years. The drainage coefficients were calculated by subtracting basic infiltrations rate from consecutive days rainfall for RI of 5, 10, 15 and 20 years
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