Gradients in Nearshore W

Temperature Aug-Oct, 2

Matt Kaplinski

and Josh Korma

>19.1

<13.4 >19.1 Bill Vernieu, GCMRC, 20
m10 RM 64.6L

CH 1m 2m 3m 5m 10

deg C

13.013.514.014.515.015.516.016.517.017.518.0

24JUL00:06:00 24JUL00:12:00 24JUL00:18:00 25JUL00:00:00 25JUL00:06:00 
Hypotheses to Test for 2004 N

Water Temperature Stu

•

Isolation of Nearshore

Environment

–

Nearshore

warming will vary with extent of hyd

(talus<low angle<backwater).

–

Higher fluctuations will decrease residence time 

environments and reduce nearshore

warming

•

Air-Water Temperature Gradient

–

Nearshore

warming will be greatest when d

iffer

water and air temperature is large (May-Aug).

–

Steadier flows that cause nearshore

warming du

months will have little effect during spring and fconditions do not support nearshore

warming.
‘Experimental Design’ of 2004 

Period Air Temperature and 

Solar Insolation

DF

Late-August High H

(

Early-September

High

L

(5

Late-October

L

o

w L

(5

Flow Effect: August vs. SeptembeAmbient Effect: September vs. Octob
Methods

• Deployed string of temperature loggers from 2.5 – 2

increments (mid-Aug to late Oct.) on the bottom

• 3 Sites (Glen Canyon (-3.5 mile), Eminence (42.5), 

mile) – contrast in mainstem water temperatures

• 3 Habitat types (backwater, low angle sand or cobbl

in hydraulic isolation

• Replicate lines for each habitat type per site• 8 loggers/line * 3 habitat types * 2 replicates * 3 site• Measured vertical gradient in water temperature ove

inundated loggers for brief periods in Aug. and Sep. bottom)
Logger Line

2,500

17,500

15,000

12,500

10,000

7,500

5,000

20,000

8

18,0

Eminence Backwater

Logger Temperatures Backwater Line 1

13.013.514.014.515.015.516.016.517.017.518.0

Aug/24

12:00

Aug/25

0:00

Aug/25

12:00

Aug/26

0:00

Aug/26

12:00

Aug/27

0:00

Aug/27

12:00

Aug/28

0:00

Water Temperature (C)

2,500 5,000 7,500 10,000 12,500 15,000 17
Eminence Backwater

Logger Temperatures Backwater Line 1

13.013.514.014.515.015.516.016.517.0

Aug/21

12:00

Aug/22 0:00

Aug/22

12:00

Aug/23 0:00

Aug/23

12:00

Aug/24 0:00

Aug/24

12:00

Aug/2

Water Temperature (C)

2,500 5,000 7,500 10,000 12,500 15,000 17,500 

Logger Te

mperatures Backwater Line 1

13.013.514.014.515.015.516.016.517.0

Aug/24

12:00

Aug/25

0:00

Aug/25

12:00

Aug/26

0:00

Aug/26

12:00

Aug/27

0:00

Aug/27

12:00

Aug/28

0:00

Aug/28

12:00

Water Temperature (C)

2,500 5,000 7,500 10,000 12,500 15,000 17,500 
Eminence Shorelines (Low vs. Steep 

Sandy Shoreline (Line 3)

13.013.514.014.515.015.516.016.517.0

Aug/24

12:00

Aug/25

0:00

Aug/25

12:00

Aug/26

0:00

Aug/26

12:00

Aug/27

0:00

Aug/27

12:00

Aug/28

0:00

Aug/28

12:00

Water Temperature (C)

2,500 5,000 7,500 10,000 12,500 15,000 17,500 

Talus (Line 5)

13.013.514.014.515.015.516.016.517.0

Aug/21

12:00

Aug/22 0:00

Aug/22

12:00

Aug/23 0:00 Aug/23

12:00

Aug/24 0:00

Aug/24

12:00

Aug/2

Water Temperature (C)

2,500 2,500 7,500 10,000 12,500 15,000 17,500 
August vs. September Eminence Bac

September - B

ackw

ater Line 1

12141618202224

Sep/4 12:00

Sep/5 0:00

Sep/5 12:00

Sep/6 0:00

Sep/6 12:00

Sep/7 0:00

Sep/7 12:00

Sep/8 

Water Temperature(C)

2,500 5,000 7,500 10,000 12,500 15,000 17,50

August - B

a

c

k

w

ater Line 1

12141618202224

Aug/21

12:00

Aug/22 0:00

Aug/22

12:00

Aug/23 0:00

Aug/23

12:00

Aug/24 0:00

Aug/24

12:00

Aug/2

Water Temperature (C)

2,500 5,000 7,500 10,000 12,500 15,000 17,50
Conclusions

• In general nearshore-offshore warming under fluctuatin

small (0-2 C).

• Strong seasonal component to nearshore warming (Sept

warming potential during early-summer months when dis low and air temperature and solar insolation are high.

• More warming (relative to GCD release temp.) under 5-

longer travel time. 

• Strong effect of site isolation with backwaters showing 

Inconsequential warming in talus habitats.

• To test the effects of fluctuating flows on nearshore war

comparison would be Sunday vs. Weekday operations. comparison confounded by seasonal and GCD release te

• Calibrated thermal imaging probably best way to quanti

high spatial variation.
Nearshore Warming Summ

PermanentInundation

VarialZone

August 2.5 kcfs vs. 

10 kcfs

2.5 kcfs vs. 17.5 kcfs

September & October

2.5 kcfs vs. 5 kcfs

2.5 kcfs vs. 10 ckfs

Month Site Avg. Max Avg. Max 

Aug Backwater line-1 0.49 2.10 0.46 2.92 

Backwater line-2 0.62 2.91 0.98 6.69Shoreline line-3 0.44 1.94 0.78 5.53Talus line-4 -0.09 0.24 0.03 2.99Talus line-5 0.08 1.34 0.24 3.91

Sept Backwater line-1 0.56 0.88 -0.12 9.20 

Backwater line-2 1.05 1.97 1.26 4.74Shoreline line-3 0.40 4.76Talus line-4 0.04 3.10Talus line-5 0.20 5.26

Oct Backwater line-1 0.31 0.74 1.09 3.14 

Backwater line-2Shoreline line-3 -0.15 1.70Talus line-4 -0.40 1.87Talus line-5 0.01 0.03 0.06 1.10

Permanent Zone Varial Zone