Tracer Test
An
extensive 4-km tracer test was designed, coordinated, and carried out
by Rob Ryan. Reconnaissance field work was carried out in March 2007;
dye tests to approximate travel times were carried out in May, 2007;
the actual field test was carried out from August 1 - 9, 2007 under low
flow conditions. The
test was repeated May 22 - 31, 2008 under higher base flow conditions.
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Location map for tracer test.
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Tracer
Test Summary
• Preliminary colorimetric
tests carried out in May 2007 to approximate total travel time and to
design test
• Tracer test conducted over approximately 4 km reach from Aug 1-9, 2007
• Test broken up into two parts, one downstream, then one upstream
• Bromide injection used; rhodamine dye used simultaneously to
colorimetrically
check for first arrival to set ISCOs
• Field deployment was 24/7 for 9 days; 43 person-slots of help (paid+
volunteer)
• No rain; flows very low
• Test conducted over a pattern of four different land uses/land
cover types
- Park/forest, older residential, heavy commercial, mixed light
commercial/residential
• Hypothesis is that hyporheic exchange will vary as a
function of
stream conditionrelated to land use
• 1200 samples collected
• IC analysis of all samples
• OTIS model being calibrated to data
• Results will be used as one input to groundwater model
• Test were repeated May 22-31 2008 under higher base flow conditions; 1400
samples analyzed on the IC.
• Results presented at Fall 2008 AGU.
• Two manuscripts were published - one on results and one on methods.
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 Tracy Kerchkof and Phil
Larson preparing bromide injection solution. |
Rob Ryan carrying out dye test check. |
 Sarah Poole taking flow measurements with Chrissy
Runyan. |
 Peter Lapa-Lilly assisting Rob Ryan with mixing up
the bromide solution. |