Question

A catchment is having total area of 60 hectares. The rainfall intensity relation with duration for this catchment is given by the relation I = 100/(t+20), where I is in cm/h and t is duration of rain in min. (a) Draw the graph of rainfall intensity relation with duration at 10 min interval? (b) What will be the storm water runoff from this catchment if the average imperviousness factor is 0.63, and time of concentration is 35 min? (c) If population density of the area is 350 persons per hectare and water consumption is 170 LPCD, what will be the design discharge for separate system and combined system?

Answer 1

Catchnment areo, A Go hectane Gi and dunctiont) anfell nlensity Co iven elction ship 100 t → noin moin I O 3.33 a. 5 1.61 .42 1.25 1-1l 50 8O 0.9o Average inopero vious fado ,,I-K = 0.63 ine concentration) tc - 35 noin "aationdl fonmula @ R-Rainfall is!ensity in mhD stoam clunodion ' is not given, then conmsider t-t

Page :2 ational Joomm la c 3Smin AIR A Pne a in ha) Cro/s) R- Reinfall intensiy A: ooha 1ニ0.63 , , , inlenat +20 35+20 360 oun hence stoom water nunoft o pulation density350 personsha . Total Population -350 6 waters consunoption - 10 0pcd a pont of cocders supplied is Convented into wcaste od en

Ca pen capitcu sewoage flous per copita voato aupply x fa ctor that me ans 80% 액 supplied cocdero :. pen capta Sewage flow = 0.8 x1700pcd= 136,0 pcd Dry wecrthen slow CHWF= Population x Per capita CpwF) sewage slous 1Pyou are consider셩/ facto-O 8 hen, DWF and it you Considen a peak f AC40イ Q, then cd0wF033052- -

Sepcucde systen not cons idena e ca 2 Comobined syo leno O. 0662 + 1 . 9 | If you consider a peak actor 2

RAINFALLINTENSITY - TIME CURVE 6 5 4 3 1 0 0 20 40 60 80 100 120 TIME MIN