cee5734_week2_2011

cee5734_week2_2011 - CEE 5734 Urban Hydrology and...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Glenn E. Moglen Department of Civil & Environmental Engineering Virginia Tech 1. Complete Rational Method Design 2. Introduction to SCS / NRCS Methods CEE 5734 – Urban Hydrology and Stormwater Management Week 2
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Questions Review of Week 1 Finish Rational Method Design Start – SCS Methods Introduction Definitions/Concepts Major quantities Curve Number Time of Concentration SCS Graphical Method Today’s Agenda
Background image of page 2
If submitting homework electronically: Submit via “Digital Dropbox” (please do NOT use the “Assignment” link) Naming scheme: Please use something like: “xxxx_Homework_#.pdf” when submitting Submit a single document preferably a .pdf or .doc file. Multiple file submissions are unwieldy. If sending an email, please include “5734” in the subject line. Some Administrative Stuff
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Need to get velocity in 27 inch pipe. Use circular geometry table (see website): From table, y/d = 0.77. (also note that A/d 2 = 0.6489), therefore: Travel time in pipe is 600 ft / 1.2 ft/s = 500 s (8.3 min) Sample Rational Method Calculation – Pipe 1-2 (cont.) ( 29 2930 . 0 ) 001 . 0 ( 49 . 1 030 . 0 ) 0 . 4 ( 25 . 2 1 49 . 1 1 2 / 1 3 / 8 2 / 1 3 / 8 3 / 8 3 / 2 = = = S n Q d d AR ft/s 2 . 1 ) 25 . 2 ( 6489 . 0 0 . 4 2 2 2 = = = = d d A Q A Q v
Background image of page 4
Sample Rational Method Calculation – Area 2 Runoff to Inlet 2: From Blacksburg IDF curve, precipitation intensity is: 4.72 in/hr (for 10-year, 9 minute duration- interpolated) A 1 = 5.3 C 1 = 0.20 T c,1 = 15 min A 2 = 7.2 C 2 = 0.40 T c,2 = 9 min A 3 = 6.4 C 3 = 0.60 T c,3 = 7 min L 1-2 = 600 ft T t,1-2 =8.3 min L 2-3 = 500 ft T t,2-3 = ??? Pipe 1-2 Pipe 2-3 Pipe 3… s ft 14 s ft 5936 . 13 ) 2 . 7 ( ) 72 . 4 ( ) 40 . 0 ( 3 3 = = = = ciA Q p
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
You might think Pipe 2-3 carries 4 + 14 = 18 ft 3 /s. But longest T c controls. T c coming from Area 1 is 15 + 8.3 = 23 minutes T c coming from Area 2 is 9 minutes. T c = 23 minutes controls. Sample Rational Method Calculation – Pipe 2-3 A 1 = 5.3 C 1 = 0.20 T c,1 = 15 min A 2 = 7.2 C 2 = 0.40 T c,2 = 9 min A 3 = 6.4 C 3 = 0.60 T c,3 = 7 min L 1-2 = 600 ft T t,1-2 =8.3 min L 2-3 = 500 ft T t,2-3 = ??? Pipe 1-2 Pipe 2-3 Pipe 3…
Background image of page 6
Calculated weighted c value: For T c = 23 minutes, i = 3.23 in/hr Since 14 ft 3 /s from Area 2 alone is greater than the combined area, 14 ft 3 /s is the design discharge for pipe. Sample Rational Method Calculation
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 43

cee5734_week2_2011 - CEE 5734 Urban Hydrology and...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online