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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
Copyright © 2013 Wildland Hydrology
Stream Habitat Measurement Techniques Day 2: Field Day
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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.
Copyright © 2013 Wildland Hydrology
Stream Habitat Measurement Techniques Day 2: Field Day
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1
5
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2
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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).
Copyright © 2013 Wildland Hydrology
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: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Copyright © 2013 Wildland Hydrology
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