HYDRAULICS BRANCH OFFICIAL FILE COPY

PAP-566

WHIN BORROWED RETURN PROMPTLY

CALIBRATION OF SMALL PARSHALL FLUMES FOR USE IN MOUNTAIN STREAMS

THE MATERIAL FOR PROJECT NWM-USBR-HP-1,RO IS PERMANTLY RETAINED IN THIS PAP FOR COMPLIANCE WITH QUALITY ASSURANCE REQUIREMENTS.

CONTENTS:

1. COPY OF SCIENTIFIC DATA BOOK

2. TECHNICAL PROCEDURE

3. NNWS1 - USBR QA CALIBRATION FORMS

4. FINAL REPORT R-90-03

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' M I N • DI• ' I' •

Calibration of small Parshall flumes for use in mountain streams

Uman..•.

1.1 To determine the accuracy of small Parshall flumes for measuring mountain stream flow. This procedure provides a guide for USBR personnel and contractors to perform the described activity. From this procedure, the Department of Enemy (DOE) and the Nuclear Regulatory Camission (NRC) can evaluate these activities for meeting requirements of the NNWSI Project, and competent, trained personnel can reproduce the work.

1.2 This procedure describes the components of the work, the principles of the methods used, and their limits. It also describes the detailed methods to be used for calibration, operation and performance verifi-cation of any equipment. In addition, it defines the requirements for data acceptance, documentation, and control; and it provides a means of data traceability.

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2.1 This procedure applies to all USBR personnel and their contractors who may perform work referred to in Para. 1.1, or use data obtained from this procedure if it is deemed to potentially affect public health and safety as related to a nuclear waste repository.

2.2 All data derived from this procedure that are presented to support licensing of the NNWSI Project repository, and any equipment calibra-tions or recalibrations that may be required shall be in accordance with this technical procedure. Variations are allowed only if and when this procedure is formally revised, or otherwise modified, as described in Section 8.

3.0 PERSONNEL, RFSpCNSIBITTTiTTF_4. The Principal Investigator (PI) is responsible for assuring full compliance with this procedure. Per QMP-2.02 and QMP-2.03, the PI shall require that all personnel assigned to work under this procedure shall have the necessary technical training, experience, and personal skills, to adequately perform this procedure; and they shall have a working knowledge of the USBR QA Manual. Responsibilities of others including the reviewer(s), contributing investigators, QA Office and the Technical Program Officer as described in QUIP-5.01.

4.0 DETAIIED Pte. This work contributes to USGS efforts to accurately determine streamflow rates for site characterization on the NNWSI Project.

4.1 Objective: Calibration of Parshall flumes for or used in high mountain streams.

NWM USHR-HP-1, RO Page 2 of 6

4.2 Methods Used: A 16 foot long- by 8 foot wide- by 3 foot deep box will be used to contain a fixed representation of a mountain stream channel with channel shape, slope, and roughness (3/8 to 6 inch particle roughness).

For some tests actual and/or representations of large boulders up to about 2 feet in diameter will be placed in cluster conformations on the fixed channel bed to provide enemy dissipation.

Each Parshall flume will be assembled and checked for dimensional tolerance conformity. If the flume dimensions are within + 1% of throat width and approach flow can be made to be uniformly distributed then the standard USBR Water Measurement Manual calibrations for properly set and installed Parshall flumes will be adopted as target calibrations. If the target calibrations can not be accomplished by crest elevation set and boulder cluster enemy dissipation, then unique calibrations will be done using the control weirs.

For the laboratory calibration checks, the control measuring station heads will be measured using rules with IT= minimum division (QUIP exempt 12.01 Par 5.5). To attain the potential accuracy of ± 3% for a 6-inch Parshall flume to within _+ 6mm at 3.00 cfs. The V-notch weir for potential accuracy of ± 1% would have to be read to within ± ]nun at 1.0 cfs. The rectangular weir for potential accuracy of _+ 1% would have to be read to within _+ 1.5m at 5 cfs. Head measuring rule zero reference elevations will be determined using spirit levels and rules (QMP exempt 12.01 Par 5.5). For information purposes, laboratory readings of head will be compared to digital recording equipment that will be used in the field. This equipment will be checked for hysteresis, linearity, float lag, and sensitivity. Digital recording equipment calibration procedures may be provided by others if used in other technical procedures.

The control discharge measurement will be done with Kindsvater type v-notch and contracted weirs, dimensionally set and calibrated according to the National Bureau of Standards Special Publication Number 421, pages 24 to 30. The geometric control for weirs and flumes will be by rules (QUIP exempt 12.01 Par 5.5) checked before and after calibration series and adjusted when needed.

A summary of the method used is as follows:

(a) Build simulation of a cleared out portion of a mountain stream and install control measuring weirs, (b) Set Parshall flume at test elevation, (c) obtain calibration check data by varying flow and compare with standard manual calibration, (d) If Weir flow comparisons deviate more than 6% and accuracy cannot be improved by resetting flume, then do stage discharge check calibration, (e) Collect additional data for oonplete calibration, (f) For some tests place individual and combinations of boulders at varying distances from the

NWM USSR-HP-1, RO Page 3 of 6

entrance to establish velocity approach effects and determine required distance upstream from the flume, (g) Determine hydraulic installation instructions for the setup of small Parshall flumes in mountain streams.

4.3 Alternative Method(s) Considered: There are no other methods appropriate to this work.

4.4 Materials/Equipment Required:

Spirit levels and rules with minimum divisions of lim (QMP exempt 12.01 Par 5.5) will be used to measure heads. Kindsvater V-notch and contracted rectangular weirs (National Bureau of Standards Special Publications Number 421 pages 24 to 30) will be used to measure discharge. The V-notch weir with potential accuracy of _+ 1% would have to be read to within _+ im at 1.0 cfs. The rectangular weir with potential accuracy of _+ 1% would have to be read to within + 1.5mm at 5 cfs.

4.5 Assumptions Affecting the Procedure: That Parshall flumes can be set high enough and far enough from boulder disturbances so that the standard potential accuracy error span is not increased by no more than 2 percentage points or that non-standard approach flow can be made stable enough for unique calibration.

4.6 Data Information: No site characterization data comes from this procedure.

4.6.1 Quantitative/Qualitative Criteria - Standard prefab Parshall flumes can be purchased and assembled and calibrated according to USER Water Measurement Manual page 43 through 85 and page 273 or NBS Special Publication Number 421 page 24 through 30. Deviation of throat width can be compensated by area proportion.

4.7 Limitations: Discharge limits for the weirs are from 0.046 to 5 cfs.

4.8 Other: None.

5.0 CAITTRMON REQUIREMENTS. calibration is required as a part of this technical procedure. When calibrations are required, all instruments and methods when applicable, will be calibrated in compliance with the Instrimlent Calibration Procedure (NNWSI-USBR-QNP-12.01) prior to obtaining data that will be cited to support licensing the NNWSI Project.

5.1 Calibration Responsibility: The PI is responsible for calibrations required by this procedure. Calibration will be in accordance with procedures described or referenced in Para. 5.2. Maintenance of all calibration records described in Para. 5.3 may be done by a con-tributing investigator under the direct supervision of the PI.

NWM-USBR-HP-1, RO Page 4 of 6

5.2 Calibration Procedure: V-notch weir and rectangular weir.

5.2.1 Calibration of the weir dimensions and gage rule zero elevation relative to crest will be determined by spirit level and rules (QMP exempt 12.01 Par 5.5). Discharge calibrations will be determined from the as built dimensions as per NBS Special Publication Number 421, 1975, pages 24 through 30. Calibration will be done before work begins and after work is complete.

5.3 Calibration Records: Calibration data will be entered in a notebook or other organized documentation. A field notebook will be used if the test equipment is used in the field. These notebooks or other documents shall be maintained as described in the Document Control Procedure (NNWSI-USSR-QMP-6.01) and stored in accordance with the QA Records Management Procedure (NNWSI-USBR-QMP-17.01). Minimum data will include instrument type, its identification and location, cali-bration procedure used, its date, the standard used, its range and accuracy, recalibration due date, responsible division subunit, any pertinent observations and the name of the person calibrating the instrument. Calibration entries shall be signed and dated by the person performing the calibration and filed with the QA Office.

5.4 Labeling of Equipment Calibration Status: In compliance with NNWSI-USBR-QMP-12.01, a sticker will be affixed to each piece of equipment used in this procedure denoting the calibration status according to one of the following three categories:

a) Equipment identification, date calibrated, date recalibration is due, procedure number and calibrator;

b) Equipment identification, "OPERATOR To CALIBRATE", and the procedure number; or

c) Equipment identification and "NO CALIBRATION REQUIRED".

6.0 T'TCATION AND CONTROL OF SAMPIFS. Samples will not be collected as part of this procedure.

7.0 QUALI'T'Y ASSURANCE Rte. All information collected and recorded under this procedure that is to be used in support of the NNWSI Project licensing process is required to be a part of the official USBR record. Input needed to process the information as a record includes: title or description, subject, originator, date of the document, and whether it is an original, a revision or an addendum.

Specific items from this procedure that will constitute a record are test notes, data and calibrations, USER Hydraulics Branch data files (FL numbers), Denver; copies of calibrations, data and approved procedures relating field installation and use. All records except final reports will be kept in a scientific notebook.

NWM-USBR-HP-1, RO Page 5 of 6

7.1 Notebooks or other organized documentation will be prepared as appro-priate by the PI or a contributing investigator to record data from this procedure and shall include any information considered by the originator to be pertinent. When data are kept in loose-leaf form, each page will be numbered consecutively and chronologically. All documents will be signed or initialed and dated by the investigator on a daily basis when entries are made. Any revisions will be lined out, initialed, and dated.

7.2 All data collected and the applicability of methods used in this procedure will be reviewed and cosigned by a peer or supervisor of the investigator knowledgeable with the objectives of this procedure in accordance with NNWSI~JSBR-QMP-6.01, Para. 4.2.2; and as such are acknowledged by both the investigator and the reviewer to be accept-able and meaningful data that meet appropriate quantitative and qualitative acceptance criteria. Unacceptable data shall be iden-tified appropriate to the form of the data.

8.0 MDMCATIONS. When field modifications become necessary, per Para. 4.8, QMP-5.01, the PI shall fully document the changes, submit the documentation for the same review signature and distribution process as for the original procedure, and indicate whether the change should result in a subsequent revision to the technical procedure. The documentation will be reviewed within 30 days.

None.

10.0 ATTACHMENTS. The following attachments are included with this technical procedure for the purpose of examples as described:

Copies of pertinent parts of references and manuals:

(a) USER Water Measurement Manual, pages 43 through 85 and page 273.

(b) Bureau of Standards Special Publication Number 421, pages 24 to 30.

Phil Burgi

NWM-USBR-HP-1, RO Page 6 of 6

11.0 APPROVAL. This technical procedure shall become effective upon its approval as noted by completion of all the following signatures and dates.

Prepared by: Russ Dodge' Date

TPO, NNWSI/USB9:' David Harris

Quality Assurance: Robert Peterson

N~lf Date

91 Date

._-/ _g(~ Date

NNWSI-USBR-QMP-12.01, RO Attachment 1 Page 1 of 1

NNWSI-USBR QA CALIBRATION FORM

Instrument Description 3 C RcL,cl y\! it- o-y- we-, fi Nc,e e-

Identification Number U S Q R - ELCr— 3 0

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Calibration Range and Accuracy G , -4 O ~~, , U U "S

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Comments: LOe- w Alvn,,--vi si con S 56Lt~~ CLCUd V-

NNWSI-USBR-QMP-12.01, RO Attachment 1 Page 1 of 1

NNWSI-USBR QA CALIBRATION FORM

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R-90-03

EFFECTS OF MOUNTAIN STREAM I TOPOGRAPHY ON THE ACCURACY

OF SMALL PARSHALL FLUMES

February 1990

U.S. DEPARTMENT OF THE INTERIOR Bureau of Reclamation

Denver Office Research and Laboratory Services Division

Hydraulics Branch

7-2090 (4-81) Bureau of Reclamation TECHNICAL REPORT STANDARD TITLE PAGF

I. REPORT NO. ~V HAi. - N'1' lty7w• G '1i 3. RECIPIENT'S CATALOG NO.

R-90-03 TITLE AND SUBTITLE 5. REPORT DATE

February 1990 EFFECTS OF MOUNTAIN STREAM 6. PERFORMING ORGANIZATION CODE TOPOGRAPHY ON THE ACCURACY OF SMALL PARSHALL FLUMES D-3750

7. AUTHOR(S) S. PERFORMING ORGANIZATION

Russell A. Dodge REPORT NO.

R-90-03 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NO.

Bureau of Reclamation Denver Office 11. CONTRACT OR GRANT NO. Denver CO 80225

13. TYPE OF REPORT AND PERIOD COVERED

12. SPONSORING AGENCY NAME AND ADDRESS

Same

14. SPONSORING AGENCY CODE

DIBR 15. SUPPLEMENTARY NOTES

Microfiche and hard copy available at the Denver Office, Denver, Colorado.

16. ABSTRACT

Full-scale 6- and 9-inch Parshall flumes were tested in a 16-foot-long laboratory test facility that simulated steep mountain stream approach flow. Observations and tests indicated that the approach pool length should be cleaned out to limit rock and boulder protrusions to 3 inches. Then a prescribed boulder cluster should be placed at midpool length.

17. KEY WORDS AND DOCUMENT ANALYSIS

a. DESCRIPTORS— water measurement/ Parshall flumes/ steep channels/ large roughness/

accuracy

b. IDENTIFIERS— / Yucca Mountain

c. COSATI Field/Group COWRR: SRIM: 18. DISTRIBUTION STATEMENT 19. SECURITY CLASS 21. NO. OF PAGE

(THIS REPORT) 15 UNCLASSIFIED

20. SECURITY CLASS 22. PRICE (THIS PAGE)

UNCLASSIFIED

I

R-90-03

EFFECTS OF MOUNTAIN STREAM TOPOGRAPHY ON THE ACCURACY

OF SMALL PARSHALL FLUMES r

LD by Russell A. Dodge

Hydraulics Branch Research and Laboratory Services Division

Denver Office Denver, Colorado

February 1990

U - UNITED STATES DEPARTMENT OF THE INTERIOR * BUREAU OF RECLAMATION

7

ILO ACKNOWLEDGMENTS

D The continued help of Pat McKinley, USGS, during the tests, data analyses, and review of this report is greatly appreciated. Bob Richardson and Dave Harris guided and monitored the required Quality Assurance details. Pete Julius took the documentary

Q videos.

i.

In 1 Mission: As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our

nationally owned public lands and natural and cultural resources. This includes fostering wise use of our land and water resources, protecting our fish and wildlife, preserving the environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also promotes the goals of the Take Pride in America campaign by encouraging stewardship and citizen responsibility for the public lands and promoting citizen participation in their care. The Department also has a major responsibility for American Indian reservation communities and for people who live in Island Territories under U.S. Administration.

I n

H

CONTENTS Page

Purpose........................................................... 1

Background........................................................ 1

Conclusions........................................................ 1

Laboratory test facility ................................................ 2

Laboratory measurements ............................................. 3

Initial observations ................................................... 3

Test results ........................................................ 4

TABLES Table

1 Calibration curves developed from laboratory tests .................. 5 2 Comparison of percent error between equation fit discharge

and weir discharge ........................................ 5 3 Comparison of percent deviation between standard Parshall

flume equation discharge and weir discharge ..................... 5 4 Comparison of different head measuring methods ................... 6

FIGURES Figure

1 Placement of boulders in stream channel .......................... %I 2 The 16-foot-long test facility with Parshall flume and

V-notch weir ............................................. 7 3 Looking upstream at cobble roughness embedded in mortar ........... 8 4 Closeup view of V-notch weir .................................. 8 5 Downstream view of wing walls ................................. 9 6 Looking upstream at sandbags representing boulders ................. 9 7 Calibration for 9-inch Parshall flume with rock cluster ................ 10 8 Calibration for 9-inch Parshall flume without rock cluster ............. 10 9 Calibration for 6-inch Parshall flume with rock cluster ................ 11

10 Calibration for 6-inch Parshall flume without rock cluster ............. 11

iii

CONTENTS - Continued

APPENDIX

Page

Parshall flume head-discharge data ................................. 13

iv

PURPOSE

Through this study, the Bureau of Reclamation determined the discharge measurement accuracy

` of small Parshall flumes installed in steep, rough channels with shallow now. Possible methods to minimize errors caused by these effects were also investigated.

BACKGROUND

The USGS (U.S. Geological Service) needs to measure small mountain stream flow to characterize drainage basins currently under investigation. Parshall flumes were chosen to measure the stream

-~ flows because of their history of satisfactory performance in measuring irrigation flow and their acceptance as standard water measuring devices. When installed to specifications, Parshall flumes have an accuracy of ±3 to 5 percent.' Most open channel water measurement structures require sufficient upstream pooling to provide good approach flow conditions and provide sufficient drop to prevent too much downstream submergence. Mountain streams often have natural drops where flumes can be perched; therefore, downstream submergence can be avoided for this case. However, poor approach conditions are common. A poor approach can cause large velocity and water surface fluctuations which prevent accurate water depth readings. Poor approach flow can also cause unbalanced channel flow where velocity is concentrated on one side. At the USGS field measurement sites the stream channel geology is pervious and thus subject to percolation of water around and under flow-measuring devices. To minimize the amount of flow that bypasses the measuring structure the depth of water upstream of the structure, the driving force for percolation, must be minimized. This is in direct conflict with the pooling requirements for attaining good approach conditions. Because of these problems, the USGS requested that Reclamation study measurement accuracy of 6- and 9-inch Parshall flumes under approach channel conditions (roughness, geometry, and slope) similar to the natural mountain stream channels at their steam gauging sites.

CONCLUSIONS

Conclusions and recommendations based on literature, observations and calibration data are as follows:

1 • Large boundary roughnesses can cause flow disturbances affecting flume head readings. The approach channel boulder and rock protrusions should be limited to about 3 inches from the general channel shape. The approach channel area covered by the pool at maximum discharge should be cleared down to this roughness limit. Even this prescribed limit can cause variable flow directions for low flows. Thus, in conjunction with the cleaned channel the Parshall flume should be set with the crest 3 inches above the channel invert.

• Although water measurement handbooks do not require 45° wing walls for flumes 6 inches and smaller, they improved the flow through the flumes considerably. The wing walls can be designed by proportioning the dimensions of the walls for a 9-inch flume.

' Water Measurement Manual, Bureau of Reclamation, Second Edition, 1981.

• Parshall flumes should be installed with the throat centered about the horizontal centroid of the flow section. This improves the flow approach and measurement on unsymmetrical stream channels that concentrate flow to one side.

• Properly placing boulder clusters (fig. 1) at the midpoint of the maximum approach pool length can improve poor approach channel conditions and reduce the expected discharge error. The comparison of the best fit equations with the weir data (table 2) indicates that the boulder clusters reduce the mean percent deviation and standard deviation.

• For measurement sites with rough approach flow, flume head measurements should be ( 1 made from a stilling well. In the laboratory tests, measuring head by visually reading the U flume wall staff gauge resulted in head measurement errors of up to ±2.5 percent (table 4) as compared to using hook gauges and stilling wells. The associated discharge ry error is ±4 percent. U

• The correlation coefficients in table 3 illustrate how the Parshall flumes can be calibrated for use in mountain streams. However, the equation coefficients and exponents are not

Q

the same as given by standard equations for tranquil flow.

• The standard deviations of the percent discharge (table 2) were equal to ±4.15 percent a or less if they are specifically calibrated for the approach channel conditions. The maximum absolute deviation magnitude was about 10 percent for the mountain stream flow calibrations.

• The mean discharge error using the standard equation rather than the calibration for mountain use (table 3) was from about 1.7 to 6 percent. The standard deviation ranged from 3.5 to 5.86 percent and maximum percent absolute deviation from 8.7 to 22 percent.

LABORATORY TEST FACILITY

The Parshall flumes were installed in the end of a 16-foot-long by 8-foot-wide by 3-foot-deep fixed 0 bed model (fig. 2). The horizontal crest of the flumes were placed 3 inches above the channel

boundary. The lateral placement was determined by centering the flume about the centroid of the q flow cross section at maximum flow. Channel roughness and slope were modeled from field site survey data and photographs. Material ranging from 3/8-inch gravel to 6-inch diameter cobbles u were placed in the mortar bedding of the model (fig. 3). The model channel was placed on a constant slope of 0.1 ft/ft. Sandbags were used in the model to represent additional large boulders Q present at the field sites.

Partially contracted Kindsvater-type weirs were used in the model as the standard for discharge O measurements. The equation coefficients for these weirs were determined from National Bureau of Standards criteria! A Kindsvater-Shen V-notch weir (fig. 4) was used for measuring model flows below about 2 ft'/s. To achieve an accuracy of ± 1 percent at 1.0 ft3/s required the associated head measurement on the weir to be accurate to within ± 1 millimeter. Larger discharges were

- a 2 NBS Special Publication No. 421, A Guide to Methods and Standards for Measurement of

Water Flow, G. Kulin and P. R. Compton, 1975. 1

2 ~J

measured using a Kindsvater-Carter rectangular weir. For the rectangular weir, head measurements within ± 1.5 millimeters were needed to attain an accuracy of ± 1 percent at 5 ft'/s. To attain the potential Parshall flume accuracy of ±3 percent, the head measurements within the flume need to be measured within ±2 percent. Therefore, the study control heads were measured using hook gauges and stilling wells.

LABORATORY MEASUREMENTS

After assembling the Parshall flumes their dimensions were checked against standard dimensions for Parshall flumes. For both the 6- and 9-inch flumes, the convergence length was 1/8 inch too long and the throat widths were 1/8 inch too wide. These dimensions are critical if the standard calibration equations are to be applied.

During the laboratory tests, flume water depths were measured and compared using the following four methods:

1. Vernier hook gauge (0.001-ft divisions) in a 4-inch stilling well was read visually.

2. Staff gauges (0.01-ft divisions) were read visually.

3. Sight glass with a scale (1-mm divisions) was connected to the stilling well and read visually.

4. Float-tape system was placed in a 12-inch stilling well. The depth signal was connected to a digital output device.

INITIAL OBSERVATIONS

During initial test runs it was observed that approach channel flow was too fast and rough for making good staff gauge readings. Although, standard specifications do not require 45° wing walls for the 6-inch and smaller flumes, wing walls were added to the 6-inch to improve the approach conditions. The walls (fig. 5) were sized by proportion to those for the standard 9-inch flume. Observation of the 6-inch flume with and without the wing walls showed that they reduced the water surface fluctuations at the measuring station. Therefore, they were installed for all calibration test measurements. However, there were still strong flow contractions at the intersection of the 45° wings and vertical wall of the flume entrance which caused extensive water surface fluctuations in the flumes.

By experimenting it was found that approach flow conditions could be improved by partially blocking the approach channel with boulders at a distance one-half the maximum pool length upstream from the flume entrance (fig. 1).

In the model, sandbags were used to represent boulders (fig. 6). The bags were placed to a height of about three-fourths of the maximum pool depth at the sides leaving a low overflow section centered at the thalweg and at a level of about one-half the maximum pool depth. The length of the low overflow section was about one-third the total maximum flow pool width.

3

TEST RESULTS

The appendix lists the flume hook gauge stilling well head data and the associated weir discharge data for the complete study. These data were used as the standard for the statistical comparisons drawn in tables 1 through 4.

Table 1 lists the least squares fit coefficient, exponent and correlation coefficient for the equation form:

Q=aHQ

Where: Q = discharge, ft3/s H = measuring head, ft a,# = coefficient and exponent derived from least squares fit

The correlation coefficients indicate, even with the mountain stream approach conditions, Parshall flumes can be calibrated for heads measured in stilling wells. Therefore, the data support the use of Parshall flumes as accurate flow measurement structures for the mountain stream sites studied. This assumes the approach channels are cleared and boulders are placed as previously described to improve the stilling arrangement.

To evaluate the goodness of fit of each regression predictor equation, the deviations of discharge from regression were calculated for each data point. Weir discharges around the regression curves are shown on figures 7 to 10. The mean standard deviation from regression and the maximum absolute sample deviation are listed in table 2. The deviation of the data about the regression lines were compared to evaluate the performance of the boulder cluster technique implemented in the calibration tests. Use of the boulder cluster reduced the mean percent error and the standard deviation of the percent error for the discharge readings. It is expected that for normally distributed data, 99.7 percent of data are within ±3 standard deviations. Therefore, any data outside of this range were not used in the fits and considered as misread. For the 9-inch flume the boulder cluster reduced the standard deviation a percentage point and the maximum deviation was increased by 2 percentage points. However, the maximum absolute deviation magnitudes were about the same with the boulder cluster and without. The 6-inch flume did not have as much improvement. Although the maximum absolute deviation was reduced by 2 percentage points, here again the magnitudes were about the same.

Table 3 lists the mean, standard deviation and the maximum discharge sample deviation from the standard Parshall flume equations using the measured heads. A comparison of the deviations between tables 2 and 3 show an overall reduction in the percent discharge error using the laboratory calibration equations in table 1. These comparisons clearly show the need to provide special calibrations for mountain stream use.

a The data in table 4 compare the different methods used to measure heads relative to the hook gauge and well measurements. The hook gauge can discriminate the water surface to within D ± 0.002 ft. The data show that using a staff gauge instead of a hook gauge and a well in a cleared mountain stream channel increases head errors 3 to 5 percent. Adding the boulder stilling cluster

4 U

D

in the cleared channel decreased the error range 1.75 to 2.5 percent. The same error ranges in terms of discharge are 4.5 to 7 percent and 3 to 4 percent, respectively.

Table 1. - Calibration curves developed from laboratory tests ( Q = aHQ )

Flume size/boulders Coefficient Exponent Correlation clustered in channel of 0 coefficient

9-inch/yes 3.0410 1.5610 0.99924 9-inch/no 3.0491 1.5798 0.99938 6-inch/yes 2.1170 1.6032 0.99762 6-inch/no 2.1893 1.6804 0.99892 9-inch/no 3.07 1.53 (standard Parshall

flume equation) 6-inch/no 2.06 1.58 (standard Parshall

flume equation)

Table 2. - Comparison of percent error between equation fit discharge and weir discharge, 100 (eq. Q - weir Q)/weir Q

Flume size/boulders Mean % Standard deviation Maximum % clustered in channel deviation of % deviations deviation

9-inch/yes 0.078 3.01 -10.6 9-inch/no 0.104 4.15 8.53 6-inch/yes 0.072 3.51 -6.54 6-inch/no 0.095 3.65 -8.54

Table 3. - Comparison of percent deviation between standard Parshall flume equation discharge (stan. Q) and weir discharge, 100 (stan. Q - weir Q)/Weir Q.

Flume size/boulders Mean % Standard deviation Maximum % clustered in channel deviation of % deviations deviation

9-inch/yes 3.49 4.33 15.3 9-inch/no 6.09 6.09 22.0 6-inch/yes -1.79 3.46 -8.7 6-inch/no 1.67 5.79 22.2

5

Table 4. - Comparison of different head measuring methods

Flume size/ Mean percent Standard Maximum absolute boulders clustered Method head error deviation head error

in channel

9-inch/yes Staff 1.78 2.26 6.86

Sight glass -0.06 1.01 2.28 scale

Digital 1.02 1.14 4.21 recorder

9-inch/no Staff 4.71 1.24 6.72

Sight glass -0.34 3.03 7.34 scale

6-inch/yes Staff 2.43 1.92 5.61

Sight glass 0.53 0.63 1.87 scale

6-inch/no Staff 2.86 5.72 13.3

Sight glass -0.01 0.50 0.88 scale

0 0 0 0 0 g

11

0

UAfP OR SLOPE 6REA~c O POOL WATER ELEV

WS, £L EV. AT FL UME

D L i~

Figure 1. - Placement of boulders in stream channel.

Figure 2. - The 16-foot-long test facility with Parshall flume and V-notch weir.

III

G~ n

fl

I is

Figure 3. - Looking upstream at cobble roughness embedded in mortar. n

r Figure 4. - Closeup view of V-notch weir.

r

i

Figure 5. - Downstream view of wing walls at entrance to 6-inch flume.

I

J Figure 6. - Looking upstream at sandbags representing boulders. J

9

-1

4.00

c~ 4-

3.00 - Q)

c~

U 2.00

Q

1.00

Q)

M

3.00 Q)

C~

U 2.00

07

Q

1.00 -

Q) C

5.00 -

0.00 Tr 0.00 0.20 0.40 0.60 0.80 1.00 1.20

Parshall Flume Head (ft) Figure 7. - Calibration for 9-inch Parshall flume with rock cluster.

0.00 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40

Parshall Flume Head (ft) Figure 8. - Calibration for 9-inch Parshall flume without rock cluster.

Nine inch Par hall Flu e with Rock Cluster

i i

Mountain Stream Ca . Y= 3. 4 X,.ss

Standard Cat. Y = 3. 07 X' s

i

Nine -inch Parshall Fl me with ut Rock Cluster

i r

i i

+ + • + • Mountain S ream Cal Y = 4 0 X 1.68

St ndard C 1. Y = 3.97 X ''

10

1.40

I 0

0

11

U 2.00

cr) 4 1

M

1.50 Q) ~.0

CCj

U 1.00

Q

~-+ 0.50 -

Q~

0.00 TTTTTTT 0.00 0.20 0.40 0.60 0.80 1.00 1.20

Parshall Flume Head (ft) Figure 9. - Calibration for 6-inch Parshall flume with rock cluster.

2.50 -

Six-inch Parshall lume with roc cluster

i

• • • • • Mou?ttain Stream Cal. Y = ,2, l2 XL 60

_ Standa d Cal. Y 2.06 X" 5

X2.50 In

11-1 CO 2.00

U ~0

1.50 ct5

U Y) 1.00

Q

0.50 -

0.00 0.00 0.20 0.40 0.60 0.80 1.00 1.20

Parshall Flume Head (ft) Figure 10. - Calibration for 6-inch Parshall flume without rock cluster.

3.00 -

Six-inch Parshall Flurne with ut rock cluster

i

• • • • • Mounta n Stream al. Y 9 XL es _ Standa I d Cal. Y = 2.06 X15

APPENDIX

Parshall flume head-discharge data

13

Nine-inch flume

Boulders

Head Discharge

(ft) (ft3/s)

0.307 0.510 1.302 4.500 1.187 3.920 1.116 3.600 0.916 2.650 0.721 1.830 0.628 1.450 0.525 1.130 0.362 0.640 0.386 0.700 0.195 0.265 0.313 0.505 0.229 0.290 0.102 0.081 0.261 0.367 0.204 3.030 1.010 2.250

No Boulders

Head Discharge

(ft) (ft3/s)

0.087 0.060 0.219 0.272 0.316 0.507 0.463 0.903 1.336 4.440 0.884 2.560 0.628 1.440 0.533 1.200 0.392 0.720 0.302 0.490 1.090 3.420

Sbr--inch flume

Boulders Head Discharge (ft) (ft3/s)

No Boulders

Head Discharge

(ft) (ft3/s)

0.392 0.457 1.149 2.620 0.484 0.636 0.911 1.830 0.486 0.670 0.824 1.560 0.659 1.160 0.561 0.870 0.766 1.370 0.470 0.640 0.833 1.690 0.355 0.420 0.965 1.970 0.560 0.826 1.050 2.230 0.457 0.590 1.131 2.480 0.340 0.350 0.578 0.895 0.260 0.228

0.151 0.085

15

Mission of the Bureau of Reclamation

The Bureau of Reclamation of the U.S. Department of the Interior is responsible for the development and conservation of the Nation's water resources in the Western United States.

The Bureau's original purpose "to provide for the reclamation of and and semiarid lands in the West" today covers a wide range of interrelated functions. These include providing municipal and industrial watersupplies; hydroelectric powergeneration; irrigation water for agriculture; water quality improvement, flood control, river navigation; river regulation and control, fish and wildlife enhancement, outdoor recreation; and research on water-related design, construction, materials, atmospheric management, and wind and solar power.

Bureau programs most frequently are the result of close cooperation with the U.S. Congress, other Federal agencies, States, local governments, academic institutions, water-user organizations, and other concerned groups.

A free pamphlet is available from the Bureau entitled "Publications for Sale." It describes some of the technical publications currently available, their cost, and how to order them. The pamphlet can be obtained upon request from the Bureau of Reclamation, Attn D-7923A, PO Box 25007, Denver Federal Center, Denver CO 80225-0007.

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