Stream Habitat Measurement Techniques Day 2: Stream Survey

Cross-Section

Cross-section Overview

Cross-Section Instructions

Sample Cross-section Survey Notes

Cross-section Survey Forms

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Stream Habitat Measurement Techniques Day 2: Field Day

1

Figure A-5. Recommended cross-section locations for bankfull cross-sectional area measurements.

Riffle / Pool SYSTEM

Point BarFLOW

FLOW

Cross-Sections

Cutbank / Outside Turn Area

Step / Pool SYSTEM

POOL

STEP

RUN

POOL

1

2

3

4

43

21

PLAN VIEW CROSS-SECTION VIEWS

PROFILE VIEW

The location of cross-section 3 is recommended for “bankfull” measurements.

Cross-Section LocationsAppropriatelocationstomeasurebankfullwidthscorrespondingtoaconsistentnormalhighflow(bankfull)stageareindicatedforriffle/poolandstep/poolchannelsinFigure A-5.

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Stream Habitat Measurement Techniques Day 2: Field Day

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Figure A-7. Bankfull width and Cross-sectional area obtained from the riffle cross-section.

Figure A-6. Typical channel features for a C Stream Type in a terraced, alluvial Valley Type VIII.

Figure A-8. Bankfull mean depth and bankfull maximum depth obtained from the riffle cross-section.

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Stream Habitat Measurement Techniques Day 2: Field Day

3

1

5

44

2

6

SURVEYOR’S ROD

FLOOD-PRONE AREA

BANKFULL STAGEMAX DEPTH

2 x MAX DEPTH

SURVEYOR’S LEVEL

Elevation / Width

STEPS: 1. Obtain a ROD READING for an Elevation at the “MAX DEPTH” Location.

2. Obtain a ROD READING for an Elevation at the “BANKFULL STAGE” Location.

3. Subtract the “Step 2” reading from the “Step 1” reading to obtain a “MAX DEPTH” value. Multiply the “MAX DEPTH” value by 2 for the “2 x MAX DEPTH” value.

4. Subtract the “2 x MAX DEPTH” value from the “Step 1 Rod Reading” for the FLOOD-PRONE AREA Location Rod Reading. Move the rod upslope, online with the cross-section until a Rod Reading for the Flood-Prone Area Location is obtained.

5. Mark the Flood-Prone Area (FPA) locations on each bank. Measure the DISTANCE between the two “FPA” locations.6. Determine the DISTANCE between the two BANKFULL Stage locations.

7. Divide the FPA WIDTH by the BANKFULL WIDTH to calculate the ENTRENCHMENT RATIO.

Figure A-9. Determining Entrenchment Ratio.

Figure A-10. Determining Width of the Flood-Prone Area (Wfpa).

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Stream Habitat Measurement Techniques Day 2: Field Day

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Cross-Section Instructions1. Setupthesurveyinginstrumentinalocationwheretheentirecross-sectioncanbeviewed.The

instrumentshouldbeplacedatanelevationhigherthanthehighestfeaturerequiredforthesurvey.Ideally,onlyoneinstrumentsetupwillberequiredtosurveytheentirecross-section;however,determiningthewidthoftheflood-proneareamayrequiremultipleinstrumentsetupsduetodensefoliage.

2. Stretchthetapeacrossthechannel(zero on left bank)makingsurethetapeisperpendiculartothebankfulldischargeflow–notthebaseflow.

3. Backsight(BS)abenchmarkorpermanentfeatureusedforrelocationorresurveyofcross-section.4. CalculateHeightofInstrument(HI);HI=BS+Elevation(knownorrelative).5. Obtainrodreadings(Fore-Sights)atmajorbreaksinbedelevationandkeyfeatures,suchasleftbankfull

(LBKF),leftedgewater(LEW),Thalweg(THL),rightedgewater(REW)andrightbankfull(RBKF).6. Recordthedistanceonthestationingtape,thecorrespondingrodheightandfeaturenotesinthe

cross-sectionforms(seeTable A-2forexample).7. Measuretheflood-proneareawidth(widthofthechannelatanelevationthatistwotimesthemaximum

bankfulldepth)(Figure A-10)‒besuretomeasureperpendiculartothefalllineofthevalley.8. Plotcross-section;calculatethebankfullcross-sectionalareaandbankfullwidth(Figure A-11,Table A-3).9. Calculatebankfullmeandepth,width/depthratioandentrenchmentratio(Table A-4).10. Usingtheappropriateregionalcurves,checktomakesurethecross-sectionalarea,bankfullwidthand

deptharereasonable.Makesurethebankfullvelocityisreasonable(velocity=bankfulldischarge/bankfullarea).

11. Recordalldataintheappropriateforms(Worksheet A-1andWorksheet A-3).

BM

86320

252221191612

5.0 1058.00

8.008.459.009.509.95

10.009.509.008.808.25

100

96.75

97.0096.5596.0095.5095.0595.0095.5096.0096.20

97.00BenchmarkLBKF

LEW

THLREW

RBKF

Lower Nevada Creek nr Helmville, MT

Team #4

8/8/06nr USGS Gauge # 12335500

10 20 00 02

SITE:Location:

Date:

Party / Notes:Distance,

Back-Sight Fore-Sight Height ofInstrumentPoint, or

STATION B S H IItem

F S Elevationftft 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

28

NOTES

REMARKSCOMMENTS

CROSS - SECTION 1SURVEY DATA

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

105.0

Table A-2. Form to record cross-section notes with example data.

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Stream Habitat Measurement Techniques Day 2: Field Day

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SITE:Location:

Date:

Party / Notes:Distance,

Back-Sight Fore-Sight Height ofInstrumentPoint, or

STATION B S H IItem

F S Elevationftft 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

28

NOTES

REMARKSCOMMENTS

CROSS - SECTION 1SURVEY DATA

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

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Stream Habitat Measurement Techniques Day 2: Field Day

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SITE: Date:

STATION B S H IItem

F S Elevationftft ftftft

29

30

31

32

35

38

42

46

33

36

39

43

47

49

53

51

55

34

37

41

45

40

44

48

50

54

52

56

NOTES REMARKSCOMMENTS

CROSS - SECTION 2SURVEY DATA

57

58

59