NATURAL STREAM - UNIFORM FLOW VER. 3-2007

CLIENT: COUNTY: DATE:

DSN BY: CHK BY: DATE: __________

COMMENTS:

~~ ~~~~~~~~~~ ~~~~~~~~ ~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~~

(sq mi) -YR DESIGN FLOW = (cfs)

CROSS SECTION

DISTANCE ELEVATION "n" UPSTREAM W.S. DOWNSTREAM W.S.

********* ********* ********* STATION ELEV STATION ELEV

(ft) (ft) (ft) (ft)

CHANNEL SLOPE(%)

(used) (computed)

W.S. EL.

MANNINGS "n"

(used) (computed)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Q, AVAIL VELOCITY

(cfs) (fps)

0 TOO LOW

Q,DESIRED

0 cfs

AREA p r END DISTS W.S. EL.

(sq ft) (ft) (ft)

~~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~ ~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~~

NOTES

*******

1. PROGRAM STARTS WITH AN ESTIMATED "n" OF 0.04. 2. ENTER UP TO 24 STATIONS PER CROSS SECTION.

PROGRAM COMPUTES THE COMPOSITE "n" FOR THE 3. USE ONLY ELEVATIONS.

SELECTED W.S. ELEV. MANUALLY ENTER THE 4. ENTER "n" FOR EACH STATION. ON INITIAL DATA

COMPUTED "n" AS THE USED "n" TO READ "Q". TO ENTRY, "n" AUTOMATICALLY REPEATS THE VALUE

ALTER "Q" ENTER A REVISED ELEV. AND RECHECK FROM THE PREVIOUS ENTRY. THEREFORE, YOU

"n" USED. NEED ONLY ENTER THE "n" WHERE IT CHANGES.

___________________

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 0.5 1 1.5 2 2.5

Ele

va

tio

n

Station

Plotted Cross section

Project/Site Name 0 Prepared by

Watershed Checked by

Tributary

Date 0

ftp://ftp-fc.sc.egov.usda.gov/WI/efh/efh-chapter3.pdf

1 Basic "n"

Earth 0.020

Rock 0.025

Fine Gravel 0.028

2 Irregular or Roughness of Channel Sides and Bottom

Smooth 0.000

Minor 0.005

Moderate 0.010

Severe 0.020

3 Changes in Size and Shape of Cross Section

Gradual Changes 0.000

Occasional Changes 0.005

Frequent and Wide Variation 0.010-0.015

4 Effect of Obstruction

Negligible 0.000

Minor 0.015

Appreciable 0.030

Severe 0.060

5 Effect of Vegetation

Low Retardance 0.005-0.010

Medium Retardance 0.010-0.025

High Retardance 0.025-0.050

Very High Retardance 0.050-0.100

SUBTOTAL, ns 0 0 0

6 Degree of Meandering 1 1 1

Minor 1

Appreciable 2

Severe 3

TOTAL n 0 0 0

Channel Coefficient of Roughness Determination ver. 3-2007

Manning's "n" Value

from EFH Notice 210-WI-77, 4/97

Minor: Lstream/Lvalley = 1.0-1.2

Appreciable: Lstream/Lvalley = 1.2-1.5

Severe: Lstream/Lvalley > 1.5

0

_

HELP SECTION

ABOUT NATURAL STREAM - UNIFORM FLOW SPREADSHEET

This spreadsheet assists you with determining the flow capacity of a

stream which varies in roughness across its profile. It allows you to

input as many as 24 sets of cross section data and assign a different

Manning's n to each, if need be.

Inputs include: watershed area, design storm frequency, design peak

flow rate, upstream and downstream water surface stations and elevations,

cross section data, including distance, elevation and Manning's n,

used Manning's n, and water surface elevation. The last

two inputs are adjusted iteratively until the design "balances" and

the stream capacity matches or exceeds the design peak flow rate.

Outputs include: computed channel slope, composite Manning's n, flow

velocity, wetted area, wetted perimeter, hydraulic radius, and end

distances.

This spreadsheet was developed by Joe Marter, USDA Natural Resources

Conservation Service - November, 1993.

Additions were made by Scott Mueller January 2005

Additions were made by Scott Mueller March 2007

PROJECT INFORMATION

CLIENT: Enter your client's name here.

DSN BY: Enter your name or initials.

COMMENTS: Enter any pertinent job information.

COUNTY: Enter the county where the project is located.

CHK BY:______ Filled in manually by the person checking your design.

DATE: Enters today's date

DATE:______ To be filled in manually when your design is checked.

DATA INPUT SECTION

W/S AREA: Enter the total area of land, in square miles, which drains

to this portion of the stream.

-YR DESIGN FLOW: Enter the design storm frequency before this heading,

and the design peak flow rate, in cubic feet per second, after it.

In block B12 through D35 enter the cross section data taken from the

survey of the stream shot at the location you are investigating. The

distance measurements are entered in feet from an arbitrary datum on

one bank or the other. Elevations are also entered in feet from the

datum. One caution is that the two end points must be higher than the

ones adjacent to them, or the program will route to infinity! Enter

Manning's n for that segment of the cross section in column D. The

program automatically repeats this value as you fill in the table, so

you only need to enter it where it changes.

Enter upstream and downstream water surface stations and elevations

in cells F12 through I12. These values are used by the program to

calculate the channel slope for this reach of the stream.

CHANNEL SLOPE (%): The program enters the computed slope

An entry is needed for the "used" slope. This is to allow you to change

the computed value without losing it, in case you wish to

do some "what if" trials.

MANNINGS "n": The program calculates a composite n value based on the

cross section data you provided and enters it under "computed". You

must manually enter the used "n" in cell F20 for the first

trial, and then adjust it in steps to bring it as close to the computed

n as possible.

W.S. ELEV: Enter your best first guess at the design water surface

elevation in cell F24. The program will use this value to calculate

all the remaining outputs. By comparing the Q, AVAIL in cell F28 with

the design flow from above you can see if the stream has sufficient

flow capacity. If Q, AVAIL is too low, raise the water surface eleva-

tion and adjust the used n to the computed n for trial 2. Continue to

adjust the elevation and n values until the available Q is equal to

or greater than the design flow and the used n is close to the computed

one. At this point your design is balanced and the output should be

representative of the stream flow at that location during a design

storm. If you can not reach a balanced design, the stream will not

handle the design storm.

A tab for the plotted cross section was added. It uses the entered

cross section data and the computed end points for the water surface.

If you have any questions about this spreadsheet, call Steve Struss

of Wisconsin DATCP at 608/224-4629. Good luck with your designs!

Or the NRCS State Office 608/662-4422

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