ce 7995 lab report: flow and velocity measurements in a river

7/25/2019 CE 7995 Lab Report: Flow and velocity measurements in a river

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CE 799Lab#

Flow and Velocity Measurements


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1.0 INTRODUCTION

%)e &ollowing data was collected on May 1/ $015 in t)e nort) branc) o& t)e Clinton

4ier assessed &rom t)e olcott Mill Metro+ar:Farm in 4ay Mic)igan' %)e

assessment included one cross section at a run ;ust downstream o& a rier crossing'

*mbient air tem+eratures were a++ro


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Figure 2 Hand-Drawn Setch

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2.0 METHODS AND ASSUMPTIONS

%)e data collection site was 101 &t' downstream o& t)e rier crossing' %)is site was

c)osen due to t)e stability o& t)e stream at t)is location since t)is section did not

a++ear to be aAected by t)e crossing nor was it near t)e bend in t)e stream' %)e

Bow a++eared to be steady and t)e water was not turbid at t)is location'

Four diAerent met)ods were utilied to determine t)e Bow at t)is cross8section wit)

elocity o& t)e water at a +articular location widt) and de+t) being t)e data

collected &or eac) Bow calculation' First ocular estimates were made as eac) team

member became acDuainted to t)e stream estimating elocity o& t)e water along

wit) widt) and aerage de+t) o& t)e cross section' 6eeld measurements were

made using leaes and &oam to calculate elocities a&ter measuring t)e widt) o& t)e

cross section and de+t) at t)e re+resentatie +oint along t)e cross section' ot)

measurements allowed &or a better understanding o& t)e stream3s moement on

t)is +articular day )oweer t)ey are not meant to be used &or &uture calculations

and determinations'

%)e t)ird Bow measurement made was done using a mec)anical elocity meter'

%)e mec)anical meter measures elocity ia reolutions o& t)e +ro+eller'

Limitations o& t)is deice include +ossible ariations in elocity measurements due

to disturbances in Bow caused t)e +ro+eller as well as t)e instrument3s ineciency

&or measuring turbulence' %)e >nal Bow measurement was made &rom elocity

determined using an *coustic "o++ler Velocity *"VG meter' "ue to t)e deice3semission o& acoustic signals to measure t)e reBection o& t)e sound waes t)e Bow

o& t)e stream remains undisturbed at t)e +oint o& data collection' %)e stream )ad

sucient turbidity to reBect t)e signal bac: to t)e *"V' For Bow determinations

made using bot) t)e mec)anical Bowmeter and *"V t)e cross section was diided

into two8&oot bins and t)e meter was +laced at t)e center o& eac) bin' (t was

assumed t)at t)e center o& eac) bin +roided t)e re+resentatie de+t) o& t)e entire

bin' %)e >nal bin &or eac) measurement )ad ery low Bow and t)e bin was only 1'5

&t wide rat)er t)an $ &t'

%o ma:e our >nal calculation o& Manning3s roug)ness coecient we also needed to

determine t)e slo+e o& t)e water sur&ace' %o do t)is a stretc) o& rier was used

slig)tly u+stream &rom t)e cross section used to ma:e measurements &or t)e Bow

determination' %)e stretc) used began at a riHe .92 &t' u+stream &rom t)e Bow8

determination cross section and ended at t)e ne


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u+stream &rom t)e Bow8determination cross section' (t was assumed t)at t)e slo+e

o& t)is stretc) o& rier re+resented t)e slo+e at t)e cross section'

3.0 OCULAR ESTIMATES

Eac) team member &or t)e selected cross8section conducted an ocular

estimate o& t)e c)annel Bow' -cular estimates can be a aluable tool &or an

engineerI t)ey +roide an a++ro


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!a"le 2 Field $easurement

Data

$.0 MECHANICAL %ELOCIT&

MEASUREMENT

Velocity measurements were

ta:en across t)e stream using a

mec)anical meter in two8&oot interal

bins' "ue to t)e ariability in stream

Bow elocity measurements were collected once eery >e seconds until

eig)t measurements were collected &or eac) bin' )en ta:ing

measurements &or eac) bin t)e measurement location )eig)t was /0 +ercent

o& t)e de+t) &rom t)e water sur&ace' %)e +articular mec)anical elocity

meter used was a to+ setting wading rod allowing ad;ustment o& t)e

measurement de+t) wit)out getting your )ands wet' %)e elocity

measurements were aeraged &or eac) bin and t)e aerage elocity were

eac) used to calculate t)e Bow rate o& t)e stream' %)e mec)anical elocity

meter data collected is +roided in %able ,'

Stat'o"

ft

De(t)

ft

%elo't* 1

ft/se

%elo't* 2

ft/se

%elo't* 3

ft/se

%elo't* #

ft/se

%elo't* $

ft/se

%elo't* +

ft/se

%elo't* ,

ft/se

%elo't* -

ft/se

Ae!ae

%elo'

t*ft/se

Flft3

$ 0'70 0'5 0'7 0'/ 0'7 0'/ 0'7 0'/ 0'7 0'/ 0

. 1'00 0'9 1'0 1'0 0'2 1'0 0'2 0'9 1'1 0'9 1

/ 1'$5 0'9 0'9 0'2 0'2 0'2 0'9 0'9 0'9 0'9 $

2 1'$0 1'0 1'1 1'0 1'1 1'1 1'0 0'9 1'0 1'0 $

10 1',0 1'$ 1'1 1'0 1'0 1'1 1'1 1'0 1'1 1'1 $

1$ 1'$0 1'. 1'. 1', 1', 1'. 1'1 1'1 1'. 1', ,

1. 1'$0 1'1 1'. 1'5 1'1 1'1 1', 1'. 1'$ 1', ,

1/ 1'10 1'. 1'. 1'. 1'$ 1'1 1', 1'. 1'$ 1', $

12 1'00 1', 1'. 1'. 1'$ 1', 1'5 1', 1'5 1'. $$0 1'10 1', 1'5 1'. 1'$ 1'$ 1'5 1'5 1'. 1'. ,

$$ 1'10 1', 1'$ 1', 1'$ 1'1 1'$ 1'0 1'. 1'$ $

$. 0'90 1'5 1'5 1'. 1'1 1'$ 1'1 1'. 1', 1', $

$/ 1'10 1'. 1', 1'. 1'1 1'. 1'1 1', 1'$ 1', $

$2 1'15 1'. 1'1 1'$ 1'1 1'$ 1'0 1'1 0'9 1'1 $

,0 0'/0 1', 1'. 1'. 1'5 1'5 1'5 1'. 1'. 1'. 1

,$ 0'20 1', 1'1 1'1 1'$ 1'1 1'$ 1'$ 1'1 1'$ 1

Page /

't)ft

De(t)ft

%elo't*

ft/se

Flowft3/se

.,'5 1'02 1'1/ 5.'.7

.,'5 1'02 1'., /7'11

.,'5 1'02 1',1 /1'.1

.,'5 1'02 1'$, 57'2$

.,'5 1'02 1'.$ //'22

.,'5 1'02 1'$9 /0'/$

.,'5 1'02 1'.5 /2',,

*erage 1',, /$',2


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,. 0'20 1'$ 1'1 1'$ 1'1 1'1 1'1 0'9 0'9 1'1 1

,/ 0'25 0'2 0'7 0'2 0'2 0'7 0'9 0'7 0'7 0'2 1

,2 0'90 0'7 0'7 0'7 0'2 0'2 0'2 0'9 0'9 0'2 1

.0 1'00 0'5 0'/ 0'7 0'5 0'7 0'7 0'. 0'/ 0'/ 1

.$ 0'90 0'1 0'0 0'1 0'1 0'1 0'1 0'0 0'1 0'1 0

., 0'75 0'0 0'0 0'0 0'0 0'0 0'0 0'0 0'0 0'0 0

TotalFlow

#

!a"le % $echanical &elocit' $eter Data

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+.0 ACOUSTIC DOPPLER %ELOCIMETER MEASUREMENT

Velocity measurements were also collected across t)e stream using an

acoustic do++ler elocimeter *"VG in t)e same two8&oot interal bins used in

t)e mec)anical elocity meter analysis' %)e ma;or adantages to t)e *"Voer t)e mec)anical unit were being able to measure Bow w)ile not

disturbing t)e region being measured and being able to measure

turbulence' %)e *"V unit used was also to+ setting similar to t)e

mec)anical elocity meter' %)e elocity measurements &or eac) bin were

used to calculate Bow' %)e mec)anical elocity meter data collected is

+roided in %able .'

Stat'o"ft

De(t)ft

%elo't*

ft/se

Flowft3/se

$ 0'75 0'/9 1'55

. 1'10 0'7, 1'/1

/ 1',0 1'00 $'/0

2 1'$0 1'$$ $'9,

10 1',0 1'$5 ,'$5

1$ 1'$5 1'$9 ,'$,

1. 1'$0 1',. ,'$$

1/ 1'$0 1',, ,'19

12 1'10 1',, $'9,$0 1'05 1'.1 $'9/

$$ 1'10 1'$2 $'2$

$. 0'25 1',9 $',/

$/ 1'00 1'19 $',2

$2 1'10 1'12 $'/0

,0 0'70 1',. 1'22

,$ 0'20 1'02 1'7,

,. 0'90 0'92 1'7/

,/ 0'90 0'21 1'./

,2 0'90 0'20 1'...0 1'05 0'50 1'05

.$ 0'90 0',5 0'/,

., 0'.0 0'01 0'01

A!ea#3.+,

$ ft2

Flow #,.$,ft3/se

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!a"le ( AD& $eter Data

,.0 ATER SURFACE SLOPE

%)e water sur&ace slo+e was calculated by sureying t)e eleation at two +ointscorres+onding to an u+stream and downstream riHe' %)e diAerence in )eig)t

between t)e two riHes was 1'$13 and t)e distance between t)e two riHes was ,/73'

%)e resulting water sur&ace slo+e was calculated to be 0'00,, &t&t' %)e surey data

collected to calculate water sur&ace slo+e is +roided in %able 5'

Stat'o"ft

Relat'eate!

S!faeEleat'o"

ft

Slo(eft/ft

Notes

8,97 /',. 888 +stream riHe &or slo+e measurement

8,0 5'1,0'00,$

97urey station ;ust u+stream o& road riercrossing at riHe

0 888 888tart o& surey ta+e ;ust u+stream o& riercrossing

11 888 888 Centerline o& road to cross rier in riHe

101 888 888 Cross8section &or elocity measurements in run

!a"le ) Slo*e Surve' Data

-.0 CALCULATION OF MANNIN4S ROUHNESS COEFFICIENT

%)e measured stream +arameters elocity Bow slo+e etc'G were used to

calculate Manning3s roug)ness coecient &or t)e cross section o& t)e rier

e


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n N 1'.9O4$,O1$G*G

Pa!a6ete! %ale U"'t

-cular EstimateFlow G /0'$0 &t,secField Estimate FlowG /$',2 &t,sec

Mec)anical Flow G ..'/2 &t,sec

*"V Flow G .7'57 &t,sec

idt) .,'5 &t

*erage "e+t) 1'00$, &t

Qydraulic 4adius 4G 0'9521 &t

*rea *G .,'/0 &t$

ater ur&ace lo+eG

0'00,$97 &t&t

Ma""'"7s Ro)"essCoe8'e"t

%ale

-cular Estimate n0'0/0

$

Field Estimate n0'052

1

Mec)anical n0'021

$

*"V n0'07/

$

Ae!ae0.0+-

9

9.0 NARRATI%E

%)e mec)anical Bow measurements and *"V measurement were ery similar

wit)in /R o& eac) ot)er' %)e >eld estimate and ocular estimate were ,1R and $7R

diAerent t)an t)e *"V measurement res+ectiely' Considering t)e general

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ce 7995 lab report: flow and velocity measurements in a river

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