Design of a Pipe 7 101 Runoff 102 1 Link 101 8 Inflow 102 102 9 Outflow 101 2 Link 102 3 10 103 11 Outflow 102 4 5 6 In a tree network, each node can have only one outflow link. Therefore we use the convention that link numbers are the same as the upstream node number.

Get the Maximum Inflow If no inflow hydrograph exists the user can specify a peak flow for the design Use Hydrograph|Add Runoff to update Inflow hydrograph

Uniform Flow in Pipes Solve for y0 using

Critical Depth in Pipes Solution for Ycr is based on the minimum energy criterion

A Trial Pipe Design Table of feasible designs for given Q and ‘n’ Double click on a row to test trial design Click [Design] to get results of part-full flow analysis

Surcharged Pipes Due to closed top boundary resistance increases as depth y approaches diameter D. At y = 0.81963 D Q = Qfull Q/Qfull When y = 0.93815 D Q = 1.07571 Qfull. y/D

Surcharged Pipes Q > Qfull Q = Qfull Q < Qfull Energy line Q > Qfull Water surface Q = Qfull Q < Qfull MIDUSS 98 assumes uniform flow for part-full pipes

Exercise 4 Design a pipe to carry 2 c.m/s when running 75% full with a gradient of 0.4% and n = 0.013 Check for surcharged hydraulic grade line if discharge increases to 3 c.m/s