longitudinal profile -...

Stream Habitat Measurement Techniques Day 2: Stream Survey

Longitudinal Profile

Longitudinal Profile Overview

Longitudinal Profile Instructions

Plan and Profile Diagram of Longitudinal Profile, Figure A-7

Sample Longitudinal Profile Survey Notes, Table A-4

Longitudinal Profile Survey Forms

Copyright © 2013 Wildland Hydrology

Stream Habitat Measurement Techniques Day 2: Field Day

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Longitudinal ProfileThelongitudinalprofilecharacterizesaveragestreamslopesanddepthsofriffles,pools,runs,glides,rapidsandstep/pools.Theaveragewatersurfaceslopeisrequiredfordelineatingstreamtypesandisusedasanormalizationparameterfordimensionlessratios(Figure A-12).Thewatersurfaceslopesofindividualbedfeatures(facetslopes)canbecomparedusinglongitudinalprofiledata(e.g.,rifflefacetslopevs.poolfacetslope).Inaddition,thelongitudinalprofilecanbeusedtoobtainmaximumdepthofindividualbedfeaturesandbedfeaturespacing.Theaveragewatersurfaceslopeismeasuredbetweentwobedfeaturesofthesametype(e.g.,topofriffletotopofriffle)overadistanceof20to30bankfullchannelwidths.Tocalculateaverageslope,dividethechangeinwatersurfaceelevationbythestreamlengthbetweenthetwofeatures.Longitudinalprofilesrequirebasicsurveyingskillsandequipment.Becauselongitudinalprofilescoveralargedistance(20to30bankfullchannelwidths),multipleinstrumentsetupsareoftenrequired.Longitudinalprofilesaremeasuredinthedownstreamdirection.Typically,a300-foottapeislaidalongthecenterlineofthechannel(notThalweg)toobtainstreamlengthstationing.Iftheflowvelocityordepthdoesnotallowthetapetobestableatthechannelmid-point,thenstationthetapealongonesideofchannelatlowflowedgeofwater.Anelevationmeasurementandtheassociateddistancealongthetape(station)aretakenatmajorbreaksinthebedtopographyandgenerallyatthestart,mid-pointandendoffeatures(e.g.,start,mid-pointandendofriffle).Fourtypesoffeaturesaremeasuredateachstation:1.Thalweg(deepestpartofchannel)(THL),2.WaterSurface(WS),3.Bankfull(BKF)(ifagoodindicator),and4.LowBankHeight(LBH)(ifthelowestbankheightisgreaterthanbankfullstagetoindicatedegreeofincision).TheThalwegandwatersurfacemeasurementsshouldreflectbedelevationandwatersurfaceslopechangesasthestreamprogressesthroughabedfeaturesequence(e.g.,riffle,run,pool,glide).Notethestationingofthecross-sectionlocationsalongtheprofile.AnexampleprofilesurveywithsurveynotesandaplottedprofileareshowninTable A-5andFigure A-13.



2

Longitudinal Profile Instructions1. Setuptheinstrumentwithaclearlineofsighttoabenchmark.Thefirstsetupshouldreference(backsight)abenchmark(BM)ofknownelevation.Approximatethenumberandlocationofeachsetupneededbasedonpotentialline-of-sightlimitations.Theinstrumentshouldbeplacedatanelevationhigherthanthehighestfeaturerequiredforthesurvey.

2. Backsight(BS)thebenchmark(placetherodonthebenchmarkandobtainarodreading).Determinetheheightoftheinstrument(HI).HI=BMelevation+BSrodreading.

3. Startingattheupstreamendofthereach,positiona300-foottapealongthecenterlineofthechannelifflowpermitsoralongedgeofwatertoobtainstreamlengthstationing.

4. PlacetherodattheThalwegatstation0onthetape.Obtaintherodreadingandrecordthevalueintheforesight(FS)columnasshowninTable A-5.Recordwatersurface,bankfullandlowestbankheightmeasurements(iflowestbankheightisgreaterthanbankfullstage)perpendiculartothetapeatstation0asshowninFigure A-12.(Note: LBHinFigure A-12atstation0+00isthesameasBKF).

5. Continuethesamesequencedownstreamtothestart,mid-pointandendofmajorbedfeaturesandrepeatthesamemeasurementsatthenewstations.

6. Atcross-sectionintersectionlocations,notethedistance(station)onthelongitudinalprofiletape.Whenusingmultipleinstrumentsetups,takeameasurementontopofbothcross-sectionendpointstoobtaincommonelevationsofthecross-sectionandlongitudinalprofile.

7. Profileyourentirereach(20to30bankfullchannelwidthsisnormallyusedasaminimumlongitudinalprofilelengthguideline).

8. Plotthelongitudinalprofile(Figure A-13).9. Plotthecross-sectionlocationandthecorrespondingbankfullelevationonthelongitudinalprofile(Figure A-13).

10.Drawalinethroughthewatersurfacedatapointsofthesamebedfeature(e.g.,topofriffletotopofriffle)torepresenttheaveragewatersurfaceslope.Drawabest-fitlinethroughthebankfulldatapoints.

11.Determinetheaveragewatersurfaceslopeandenterintoforms(Worksheet A-1andWorksheet A-3).DeterminebankfullslopeandenterintoWorksheet A-2. Note: The averagewatersurfaceslopeandthebankfullslopeshouldbeparallel.



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Figure A-12. Plan and profile views of a longitudinal profile indicating slope and bed feature measurement locations. Note: Stationing distance in this example is measured along right edge of water (REW).

Average Water Surface Slope (S): Elevationofwatersurfaceoverstreamlengthatthesamepositionabovebedfeaturesforseveralriffle/poolorstep/poolsequences(e.g.,elevationdifferencefromthetopofriffletotopofnextriffleoverthelengthofthestream).Thisvaluewillnormallyapproximatetheaveragebankfullslope.Average Bankfull Slope (Sbkf):Theelevationdifferenceofbankfullindicatorsalongthestreamlength.Theelevationdifferencesareobtainedfromabest-fitlinedrawnbetweenbankfullindicatorsalongthelongitudinalprofile,whichisgenerallyparallelandsimilartotheaveragewatersurfaceslope(S).



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SITE:Location:

Date:

Party / Notes:

Distance, Back-Sight

Fore-Sight

Height ofInstru-mentPoint, or

STATION B S H I F S Elev.ftft ftftft

1

2

3

4

7

10

14

18

5

8

11

15

19

21

25

23

27

6

9

13

17

12

16

20

22

26

24

NOTES

LONGITUDINAL PROFILE 1SURVEY DATA

HUC: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

F S Elev.ftft

F S Elev.ftft

Fore-Sight

Fore-Sight

Elev.F S

Fore-Sight

ft ft

Elevation Elevation Elevation Elevation

Glide

e.g.Riffle

RunPool

Thalweg Water Surface Bankfull Low Bank HI

Raccoon Creek

Page 1 of 3

3/4/07Reference Reach - Stationing 0+00 thru 3+60

191710

253032

Ri�e

504635

566972

5.83

6.05

5.91

6.17

6.25

5.02

98.0898.0798.00

98.0297.63

97.03

96.6396.4496.25

95.9896.0396.73

97.53

97.6697.71

97.6897.62

97.1696.37

95.78

96.87

96.4897.58

97.5097.4697.30

99.45

99.23

99.37

99.11

99.03

98.70

Run

Pool

Glide

757990

100105112117125129135152151161

Ri�e

RunPool

GlideRi�e

Run

7.207.217.28

7.267.65

8.25

8.658.849.03

9.30

9.258.55

7.75

7.627.57

8.41

9.50

8.918.12

7.667.60

8.807.70

7.787.826.42

98.5398.5298.39

98.3798.29

98.23

98.2298.2198.20

98.2098.1898.18

98.18

98.1898.18

98.1398.08

98.0097.98

97.98

97.98

97.9897.97

97.9097.8197.73

6.756.766.89

6.916.99

7.05

7.067.077.08

7.08

7.107.10

7.10

7.107.10

7.30

7.30

7.307.28

7.207.15

7.307.31

7.387.475.99

5.28 105.28BM1

Table A-5. Sample form to record longitudinal profile notes with example data.



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Figure A-13. Plotted longitudinal profile (RIVERMorph™, 4.3).



SITE:Location:

Date:

Party / Notes:


Fore-Sight



1

2

3

4

7

10

14

18

5

8

11

15

19

21

25

23

27

6

9

13

17

12

16

20

22

26

24

NOTES


HUC: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

F S Elev.ftft

F S Elev.ftft

Fore-Sight

Fore-Sight

Elev.F S

Fore-Sight

ft ft


Glide

e.g.Riffle

RunPool




SITE:Location:

Date:

Party / Notes:


Fore-Sight



28

29

30

31

34

37

41

45

32

35

38

42

46

48

52

50

54

33

36

40

44

39

43

47

49

53

51

NOTES


HUC: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

F S Elev.ftft

F S Elev.ftft

Fore-Sight

Fore-Sight

Elev.F S

Fore-Sight

ft ft


Glide

e.g.Riffle

RunPool


longitudinal profile -...

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