Comparison of Tracer-Dilution and Comparison of Tracer-Dilution and Current-Meter Measurements Current-Meter Measurements in a Small Gravel-Bed Stream, in a Small Gravel-Bed Stream, Little Lost Man Creek, CaliforniaLittle Lost Man Creek, California

Gary W. Zellweger, Ronald J. Avanzino, and Kenneth E. Bencala (1989)

Purpose of StudyPurpose of StudyPresent and compare discharge

measurements taken by two different methods:◦Tracer-dilution◦Current-meter

Suggest how much discharge is flowing through the channel gravel

BackgroundBackgroundCurrent-meter technique preferred

method to determine discharge

Issues with current-meter method:◦ Shallow depths o Rough bottom◦ Flow through gravel o Discharge variation

Continuous tracer-dilution methods can accommodate these factors

Can be used to calculate discharge at multiple sites

Requirements:◦Tracer thoroughly mixed with stream◦Conservative tracer

Tracer-Dilution MethodTracer-Dilution Method

Can be used to calculate discharge at multiple sites

Requirements:◦Tracer thoroughly mixed with stream◦Conservative tracer

Tracer-Dilution MethodTracer-Dilution Method

Can be used to calculate discharge at multiple sites

Requirements:◦Tracer thoroughly mixed with stream◦Conservative tracer

Tracer-Dilution MethodTracer-Dilution Method

Stream discharge below injection point:

Qb = Qi (Ci –Ca)

(Cb – Ca)

Qb = Stream discharge below the injection point Qi = Injectant discharge Ci = Tracer concentration in injectant Ca = Tracer concentration in stream above injection point Cb = Tracer concentration in stream below injection point

Tracer-Dilution MethodTracer-Dilution Method

Site DescriptionSite DescriptionLittle Lost Man Creek, CACoastal 3rd order stream

◦10 km length, N-NW flow◦Late summer flows 6 L/s◦Winter high flows 5,700 L/s

Study reach = 330 m◦Poorly sorted, sand-boulder◦Gravel sediments > 1 m thick

Cl-Li pumped into stream continuously (8d)◦Chloride concentration = 170.1 g/L◦Daily injection rate = 37.29±.32 mL/min◦Mixing length = 300m

Secondary injection on 7thday◦Na, Cl, rhodamine WT (24 h)◦Mixing length = 25m

Sampled hourly with automatic samplers◦300m above◦330m below

Tracer-Dilution MethodTracer-Dilution Method

Cl analysis:◦Filtered and stored w/o light, few months◦Dionex ion chromatograph

Na analysis:◦Filtered and stored w/o light, few months◦Spectrophotometer

Rhodamine WT analysis:◦Stored in glass bottle w/o light < 10d◦Fluorescence measured, Fluorometer

Tracer-Dilution MethodTracer-Dilution Method

Current-Meter MethodCurrent-Meter MethodDischarge measured with current

meter◦Three sampling days◦Two measurements/site/day

Modified 4 locationsDepth and ave. velocity

◦Measured at 17 to 25 vertical sectionsStream discharge determined by

summing flows through each measured subsection

Tracer (Chloride) Tracer (Chloride) ConcentrationsConcentrations

Current-meter Discharge Current-meter Discharge DataData

Method ComparisonMethod Comparison

Method ComparisonMethod Comparison

Method ComparisonMethod Comparison

DiscussionDiscussionCalculated discharges:

◦Current-meter 13.0 L/s◦Tracer (25m) 15.9 L/s ◦Tracer (300m) 14.4 L/s ◦Average 13.0 L/s

DiscussionDiscussionGravel zone = 25% of channel

flowGravel moves in and out between

the surface water and gravel zone

Current-meter = surface flow only

Tracer 300m = most mixing

ConclusionConclusionWater in gravel zone moves down

channel as underflow◦Can be measureable

Affects discharge measurementsTracer-dilution and current-meter

methods can yield different valuesTracer-dilution method yields

different results over different stream lengths

Testing and Comparison of Four Ionic Testing and Comparison of Four Ionic Tracers to Measure Stream Flow Loss Tracers to Measure Stream Flow Loss

by Multiple Tracer Injectionby Multiple Tracer Injection

Gary W. Zellweger(1994)

Purpose of StudyPurpose of StudyToxic metal transport, need to know

◦Where stream is losing water◦How much water is being lost

Calculate discharge for 4 tracers used in simultaneous multiple tracer dilution◦Li, Na, Cl, Br

Define limitations of method

Site DescriptionSite DescriptionSt. Kevin Gulch, CO3rd order stream

◦Flat, wetlands source◦Summer flow =

10 L/s pH ~3.6 in August

Study reach = 570 m◦Upper stream = forested, steep, narrow◦Lower stream = smaller gradient, little

vegetation, minimal hillslope

Study DescriptionStudy DescriptionTracer solution

continuously injected at 5 wells◦Lithium chloride

and sodium bromide in stream water

Injection sites ~100m apart

Parshall flumes installed, 4 sites

Parshall FlumeParshall Flume

ResultsResultsOnly 3 injection sites operated at

a time

ResultsResults

ResultsResults

DiscussionDiscussionPrecision of 2%Discharge decreasing downstream

(8%)More effective to use different

tracers at each injection siteAll tracers were conservative in St.

Kevin Gulch (116m reach)4-18% difference in discharge

measurements between flume and tracers

Evaluating the Reliability of the Stream Evaluating the Reliability of the Stream Tracer Approach to Characterize Tracer Approach to Characterize

Stream-Subsurface Water ExchangeStream-Subsurface Water Exchange

Judson W. Harvey, Brian J. Wagner and Kenneth E Bencala (1996)

Quantifying Hyporheic Quantifying Hyporheic Interactions:Interactions:

An in-depth look at three An in-depth look at three studiesstudies

Geology 230, CSUS, Spring 2013

Presented by

Emily Siegel and Jessica Bean