stream notes october 200248, d-74, or dh-81 depth integrating samplers for suspended sediment. all...

To Aid In Securing Favorable Conditions of Water Flows

STREAM SYSTEMS TECHNOLOGY CENTER

NOTESSTREAM

Rocky Mountain Research Station October 2002

STREAM NOTES is producedquarterly by the Stream SystemsTechnology Center, RockyMountain Research Station,Fort Collins, Colorado.Larry Schmidt, Program Manager

The PRIMARY AIM is to exchangetechnical ideas and transfertechnology among scientistsworking with wildland streamsystems.

CONTRIBUTIONS are voluntaryand will be accepted at any time.They should be typewritten, single-spaced, and limited to two pages.Graphics and tables are encouraged.E-Mail: jpotyondy@ fs.fed.us

Ideas and opinions expressed arenot necessarily Forest Servicepolicy. Citations, reviews, and use oftrade names do not constituteendorsement by the USDA ForestService.

CORRESPONDENCE:E-Mail: rmrs_stream@ fs.fed.usPhone: (970) 295-5983FAX: (970) 295-5988Web Site:http://www.stream.fs.fed.us

IN THIS ISSUE• The Nature of Flow

and Sedimentin Little GraniteCreek

• Use of PDAs inStream Fieldwork

• Piedmont RegionalChannel GeometryRelationships

The Nature of Flow and SedimentMovement in Little Granite Creek

by Sandra Ryan and William Emmett

A relatively long-term database of morethan 450 measurements of sedimenttransport has been acquired through thecombined efforts of the USDA ForestService and the U.S. Geological Surveyat Little Granite Creek, a gravel-bedstream draining a 21 square milewatershed near Bondurant, Wyoming.The data spans 13 runoff seasonsbetween 1982 and 1997 and is one ofthe most comprehensive bedload andsuspended sediment datasets everassembled at one location. Sedimentdata were obtained at flows rangingfrom 0.05 bankfull to nearly twice thebankfull discharge using 3-inch Helley-Smith samplers for bedload and DH-48, D-74, or DH-81 depth integratingsamplers for suspended sediment.

All of the data are published in RockyMountain Research Station GeneralTechnical Report RMRS-GTR-90. Thedata includes rates of bedload transport,the particle-size distribution ofindividual samples, suspendedsediment load, measurements ofhydraulic geometry, and channelsurveys. The data are presented in tablesand graphs and may also be obtainedelectronically from the first author.

The primary purpose of the paper is tocharacterize the morphology andhydrology of Little Granite Creek andthe nature of bedload and suspendedmaterial transported in this gravel-bedchannel. The present article will brieflysummarize relevant results.

Flow Frequency andBankfull Discharge

Estimates of flow frequency werecalculated using Log Pearson IIIanalysis on the annual maximum seriesfor the period 1982-1992. Thecalculated 1.5-year return interval flowof 210 cfs is nearly identical to thefloodplain elevation at the gaginglocation which has a field determinedbankfull discharge value of 229 cfs.

Bed Material Composition

As is typical for gravel-bed channels,the subsurface is considerably finer thanthe surface. The D

50 of the subsurface

averages 17 mm while the D50

of thesurface is about 89 mm, or about 5 timeslarger than the subsurface. Thisindicates that the bed is well armored.


Suspended Sediment

Much more material is moved in suspension than asbedload in Little Granite Creek due to sedimentaryformations that typically produce muddy and turbidrunoff during high flows. General trends in dischargefor both suspended sediment load and bedload areshown in Figure 1. At moderate discharges, suspendedloads are about 100 times greater than bedload, and littleto no bedload is transported at commonly occurring lowflows. Rates of bedload and suspended sedimenttransport tend to converge at higher discharges becauseof the increase in the rate at which material is moved asbedload.

Rates of Bedload Transport

Total Transport - Several models, including linear,power, and piecewise regression, were fit to the bedloaddata to describe sediment rating curves. This discussionwill focus on the piecewise regression model which fitsone or more linear regression functions to differentranges of data. For a more complete discussion ofpiecewise regression applied to bedload data see Ryanet al. 2002.

Piecewise regression results in the determination ofbreakpoints, which are values on the x-axis(discharge) where a change in the slope of thedifferent linear relationships can be defined. Abreakpoint is interpreted to be an indicator of theflow at which a substantial change in the rate andnature of coarse-grained transport occurs and isuseful in defining phases of transport. Thebreakpoint for Little Granite Creek appears to beabout 171 cfs (Figure 2). Flows below the breakpoint(Phase 1), move materials that are primarily sandand small gravel at relatively low rates over a stablechannel surface. Flows above the breakpoint (Phase2) move greater and more coarse grains than Phase1, including material from both the channel surfaceand subsurface.

Figure 1. Comparison between suspended loadand bedload measured at Little Granite Creek.


Figure 2. Fractional rates of bedload transportmeasured over a wide range of discharges up toalmost 2 times bankfull discharge. A significantincrease in the rate of transport occurs and thebedload substantially coarser as flows approachand exceed bankfull discharge (229 cfs).

Emmett (1999) described a similar analysis for thedata at Little Granite Creek, using the term “explosion”to characterize the rapid increase in transport rate.Emmett’s analysis, based on visual indicators,suggested that the explosion, or the rapid increase intransport rate, occurs at about 220 cfs. While there isa small discrepancy between the explosion andbreakpoint estimates, both indicate that a substantialincrease in the amount of bedload transport begins atflows approaching bankfull, or about the 1.5-yeardischarge.

Transport by Size Fractions - Fractional transportrates in tons per day are shown in Figure 2. Theprimary constituent of all bedload samples is sand andit ranges from 100 percent of total sample weight atthe lowest flows to 20 percent at high flows. Thepresence or predominance of sand in bedload is typicalfor channels with coarse beds.

As discharge increases, there is a general tendencyfor bedload samples to become coarser. Coarse gravel(>32 mm) was rarely trapped at flows less than the

breakpoint (only 2 percent of the samples containedcoarse grains). This indicates that coarse gravelmovement below the breakpoint is essentiallynegligible. By comparison, coarse gravel was commonin samples collected at flows greater than thebreakpoint where 60 percent of the samples containedparticles larger than 32 mm and 90 percent containedgravel larger than 16 mm.

The persistence of coarse gravel in bedload samplesprovides good evidence that conditions suitable fortransporting gravel and larger grains have beenreached. This does not mean that the entire bed surfaceis in motion, but rather that representatives from anumber of size classes are mobile at flows greater thanthe breakpoint.

The identification of a breakpoint, or explosion, inthe studied gravel-bed stream indicates that there is aflow above which there is a substantial change in thenature of sediment movement. From a landmanagement perspective, knowledge of the discreteflows needed to move different sized particles instreams may be useful for determining dischargesrequired to maintain the form and function of thechannel and aquatic habitat.

References

Ryan, S.E., Porth, L.S., Troendle, C.A. 2002. Definingphases of bedload transport using piecewise regression.Earth Surf. Process. Landforms 27: 971-990.

Emmett, William W. 1999. Quantification of channel-maintenance flows in gravel-bed rivers, pp. 77-84 InWildland Hydrology, American Water ResourcesAssociation, TPS-99-3, 536 p.

Sandra Ryan, Research Hydrologist, Rocky MountainResearch Station, Laramie, WY;E-mail: [email protected] W. Emmett, Research Hydrologist, U.S.Geological Survey (retired); presently ConsultingHydrologist, Littleton, CO; E-mail:[email protected]

Copies of Ryan, S.E.; Emmett, W.W. 2002. The nature offlow and sediment movement in Little Granite creeknear Bondurant, Wyoming. Gen. Tech Rep. RMRS-GTR-90, 48 p. can be ordered by going to Web sitehttp://www.fs.fed.us/rm and clicking on “Publications:Orders/Questions.”


The Potential Use of PDAs in Stream Fieldwork

by Richard Albert

In his Stream Reconnaissance Handbook (John F.Wiley & Sons, 1998), Colin Thorne suggests thatequipment used for stream reconnaissance should weighless than 44 pounds and, ideally, fit into a backpack. Ahandheld computer, or PDA (Personal Digital Assistant),weighing less than 7 ounces might be one way ofreducing weight.

Over 40 models of consumer-oriented PDAs areavailable. All come with address book, date book, memopad, expenses, clock with alarm, To Do list, calculator,data entry using a stylus, and the ability to “partner”with your PC. Additional money buys software, extramemory, voice recording, wireless phone, Internetaccess, GPS, digital photography, e-books, peripherals,and much more. Obviously, a lot of these functions canbe used in the field.

An incredibleamount of softwareis available, much ofit inexpensive orfree. In the Palmoperating system, forexample, aresoftware calledH y d r a u l i cCalculator, QuickSurvey, FluidMechanics Tools 2,H y d r a u l i cEngineering Tools 2,Wind Chill Factor,Geo PDA, andothers that might have field uses. PDA software isn’ttoy software either. Some of it is nearly as sophisticatedas PC equivalents and most PDA software can be triedbefore buying.

My own experiences using a PDA have been fairlyordinary. I didn’t, for example, replace a perfectly goodGPS, cell phone, digital camera, or tape recorder in order

Figure 1 This article asdisplayed on a PDA screen.Scrolling is much better on aPDA than a PC.

to buy PDA-basedones. My next PDAwill have some ofthese plus mobileInternet capabilities.

I created “PDA”versions of variousstream assessmentprotocols inMicrosoft Word andtransferred them tomy PDA. They nowgo everywhere withme. These include Pfankuch channel stability, NRCSstream visual assessment protocol, Rosgen streamclassification, EPA’s RBP Habitat Assessment and acouple of others. Paperless surveys are possible with atape recorder or, even better, a PDA-based voice recorderthat also keeps a log on the PDA and eliminates an extraitem to be held.

I used MicrosoftExcel to develop aprogram thatcalculates WolmanPebble Countpercentages andc u m u l a t i v epercentages. Since Ikeep tallies bywriting directly onmy gravelometer, Ican in theory go frompencil marks to thepercentage calculatorto a data file. However, I still use paper for “mental”security reasons. Since you can backup PDAs as yougo, i.e., off load data using external memory modules,memory sticks, compact flash cards, etc., paper backuptruly is not needed.

Figure 2 Pfankuch channelstability evaluation.

Figure 3 The Wolman PebbleCount calculator. Column A(hidden) has particle sizes.


I do find navigating PDA spreadsheets to be trickybecause of the small screen size. At least one brand onthe market turns the spreadsheet sideways and uses morescreen area than is normally available for use.

One of my most used purchases has been “Convert-It”($15) that converts units of measurement. It replaces abooklet I have had for over 30-years; one that I couldnever find when I needed it. More recently, I purchased“Expedition ES” ($5). Its ad promises to turn my PDAinto a “portable surveying instrument”. Besides thePDA’s computer functions, it also employs a short pieceof string taped to the PDA case and the edge of the caseitself. I haven’t actually surveyed anything outdoors withit yet, but it seems like a pretty nifty program. While itmight not replace a laser level, it weighs nothing and isalways with you.

Since I am also a writer, I have a full-sized foldingkeyboard for my handheld and full-featured word-processing program. Nifty doesn’t begin to describe thekeyboard. Pocket-sized printers are also available. Sureyou can lug a $2,500, 6 pound laptop, but who wantsto? Theft of a PDA is not a major problem because itgoes with you, for example, to visit the bathroom.

I have also become a fan of e-books and usually haveone on my PDA to read as time permits. The availabilityof PDA e-books suggests that a whole library of technicalreferences, quality assurance plans, first-aid manuals,and so forth could be taken to the field.

Conceivably, you can access web-based documents andreal-time data (streamflow, weather reports, etc.) viaPDA wireless Internet from the field. Possibly, data couldbe sent back to the office, downloaded from equipment,e.g., continuous, automatic flow or water qualitymonitors, or used to run PDA versions of standardmodels.

Where handheld computers are heading is anybody’sguess. It has been predicted that a PDA might bereplacing your PC someday, with the PDA plugged intoa desktop docking station when in the office. This is apossibility as PDA memory increases. What is certainis that PDA, cell phone, and wireless Internet aremorphing into a single unit. If you don’t own onealready, a PDA is likely in your future.

THE USE OF PORTABLE DATARECORDERS BY THE

FOREST SERVICE

Over the past fifteen years the Forest Service hasused mobile computing systems in many datacollection projects and benefited from improveddata consistency and quality. However, as themobile computing technology evolves many of ourcomputing systems have become obsolete. Effortsare increasing throughout the agency to evaluateand implement new mobile systems for datacollection.

One such effort is the Portable Data Recorder(PDR) module of the National ResourceInformation System (NRIS) located in Fort Collins,Colorado whose primary mission is to support thedata collection needs of other NRIS modulesthrough the development of software for mobilecomputing devices. One challenge facing the staffis the vast array of mobile devices available, fromrugged handheld PCs with keyboards (Allegro,fex21) to Pocket PCs (Casio, iPaq), each offeringdifferent features and capabilities. Due to the manytypes of data collected, the different physicalenvironments in which the data is collected, and arange in user preferences, development for asingle mobile device is unwarranted. Thisincreases the challenge of building software,particularly since the various devices can employdifferent operating systems and chipsets. Tominimize some of the challenge, the group islimiting development to devices that run theWindows CE operating system.

Exiting Windows CE applications include commonStand Exam information. Applications underdevelopment include the collection of surface waterchemistry for air pollution monitoring and thecollection of invasive plant information for rangemanagement.

If you have a Windows CE device and are thinkingof developing a data collection application, contactthe PRD group and use their programmingknowledge. Contact Dan Camenson by e-mail [email protected] or call Dan directly at 970-295-5786 to discuss your programming needs.


Here are a few of my personal thoughts on buying aPDA for field use:

• Buy a low-end or refurbished model for fieldwork.A $130 PDA hitting a rock sounds better than a $500one hitting the same rock.

• Processor speed, the size of RAM memory, and acolored display are not as important as compatibilitywith PC software, seamless PC/PDA transfers, andscreen visibility in sunlight.

• A shock-resistant case with a secure belt-clip is aworthwhile purchase for even the cheapestalternative. I never hold mine over water either.

• Pocket PC, Handheld Computing, and PenComputing magazines publish individual Buyer’sGuides. The former two cover Windows CE andPalm-OS PDAs respectively, while the latter coversboth operating platforms plus commercial handhelds.

Richard Albert is Restoration Director with theDeleware Riverkeeper Network, a non-profitenvironmental organization based in WashingtonCrossing, PA. Figures used in the article areDocuments To Go files captured by ScreenShotHack on a Handspring visor PDA. Comments andquestions can be sent to [email protected]

Regional Channel Geometry Relationships for theMaryland Piedmont Hydrologic Region

For river engineering purposes, particularly in the fieldof river restoration, regional channel geometryrelationships are widely viewed as an important toolfor both assessment and design procedures. Therelationships are most useful as a first step towardpreliminary design and evaluation of river channels.

The U.S. Fish and Wildlife Survey publication,Maryland Stream Survey: Bankfull Discharge andChannel Characteristics of Streams in the PiedmontHydrologic Region by Tamara L. McCandless andRichard A. Everett is an excellent reference for how toproperly conduct a channel geometry study.

Prepared in cooperation with the Maryland StateHighway Administration and the U.S. GeologicalSurvey, the study was primarily designed to determineand analyze the hydraulic and planform characteristicsof Maryland streams and determine the applicabilityof the Rosgen Classification System to these streams.

The first phase involved detailed channel geometrysurveys at 23 stream gages operated by the USGS inthe Piedmont hydro-physiographic regions in Maryland.

Future phases will expand the work to address theCoastal Plain, Ridge and Valley, and AppalachianPlateau provinces.

The following are some of the key findings:

• Bankfull discharge is significantly related todrainage area, with about 93% of the variabilityin discharge explained by drainage area.

• Of the number of bankfull indicators examined,the floodplain break, a discrete transition fromnear vertical to near horizontal used at straightreaches or on bends lacking point bars, is theprimary indicator associated with the bankfulldischarge.

• The recurrence intervals for the bankfull dischargeranges from 1.26 to 1.75 years, and averages 1.5years.

• Width, mean depth, and cross-sectional area areall significantly related to drainage area (Figure1) and bankfull discharge and compare favorablywith those documented by previous workers.


Figure 1. Bankfull channel dimensions as a function of drainage area for Maryland Piedmont survey sites.The graphical relationships between drainage area and bankfull cross-sectional area, bankfull width, and meanbankfull depth show an extremely close correspondence to relationships published by Dunne and Leopold(1978) for the eastern United States.

• Results support applicability of the Rosgen classificationsystem to Piedmont channels; however, only a limitednumber of stream types were observed (mostly C typestreams with only the C4 type well represented).

While this study will be of particular interest to those workingin the Maryland Piedmont and the eastern United States,this study is an excellent example of how to conduct a channelgeometry study. The criteria used to select gaging stationsare well described. The discussion of bankfull indicators,including an excellent literature review of the topic, iscomprehensive and complete. Data are clearly presented andthe analysis behind the findings are factually presented andfully disclosed.

In addition, the report contains an appendix containingcomplete data, cross-section and particle size plots, color

photographs, and maps of survey sites for the 23sites surveyed. Finally, it has a well prepareddescription of the protocols used for the fieldsurveys including examples of all field forms. Inthis respect, the study can serve as a useful templatethat others could modify and apply to determinechannel geometry relationships for other hydro-physiographic regions.

Copies of this report are available at:http://www.fws.gov/r5cbfoClick on “Stream Restoration” or retrieve file:http://www.fws.gov/r5cbfo/Piedmont.pdf.

STREAM SYSTEMS TECHNOLOGY CENTERUSDA Forest ServiceRocky Mountain Research Station2150 Centre Ave., Bldg. A, Suite 368Fort Collins, CO 80526-1891

October 2002

PRSRT STDPOSTAGE & FEES PAID

USDA - FSPermit No. G-40

OFFICIAL BUSINESSPenalty for Private Use $ 300

STREAMNOTES

STREAMNOTES

IN THIS ISSUE• The Nature of Flow

and Sedimentin Little GraniteCreek

• Use of PDAs inStream Fieldwork

• Piedmont RegionalChannel GeometryRelationships

We hope that you value receiving and reading STREAM NOTES. We are required to review and updateour mailing list annually. If you wish to receive future issues, no action is required. If you would liketo be removed from the mailing list for STREAM NOTES or if the information on your mailing labelneeds to be updated, please contact us by FAX at (970-295-5988) or send an e-mail message to:[email protected].

To make this newsletter a success, we need voluntary contributions of relevant articles or items ofgeneral interest. You can help by taking the time to share innovative approaches to problem solving thatyou may have developed. We prefer short articles (2 to 3 pages in length) with graphics and photographsthat help explain ideas.

The United States Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national

origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.)

Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape etc.) should

contact USDA’s TARGET Center at 202-720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil

Rights, Room 326-W, Whitten Building, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964 (voice or TDD). USDA

is an equal opportunity provider and employer.