Monitoring of Groundwater and Surfacewater Interactions on the Walla Walla River

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Monitoring of Groundwater and Surfacewater
Interactions on the Walla Walla River

• Graduate Student Starr Silvis
• Major Professor John Selker
• Field Coordinator Bob Bower

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Presentation Outline

• Location and features of the basin
• Background
• Goals
• Methods
• Chemical Signature
• Mini-piezometers
• Temperature Profiling
• Results
• Discussion

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Location of the Walla Walla River Basin
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Water Resources for the Basin

• Surface water
• North Fork and South Fork
• Groundwater
• Alluvial aquifer
• Basalt aquifers

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Monthly Mean Flows
22 years of data 1969 - 1991
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Walla Walla River Returns!

• All river water above levied section (100
  c.f.s.) diverted for irrigation since turn of the
  century from June September
• 1998 American Rivers lists Walla Walla River as
  one of the top 20 most endangered rivers in the
  U.S.
• Bull trout and Steelhead E.S.A. listed in 1998
  and 1999
• Irrigation districts pledge to leave flow in the
  mainstem of the Walla Walla River sign agreement
  with U.S.F.W.
• 2000 13 c.f.s
• 2001 18 c.f.s.
• 2002 25 c.f.s
• 2003 - ?

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Summer 1999
Summer 2002
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Low Flow Limitations

• 2000 - all 13 c.f.s. percolated from the surface
• Possible causes
• In-stream gravel mining
• Naturally high hydraulic conductivity (Schälchli,
  1995,1992)
• Large hydraulic gradients due to low aquifer
  levels

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Aquifer Recharge

• Irrigation ditch losses
• Primarily unlined ditches
• Stream losses
• Winter recharge
• Now summer recharge too

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Study Goals

• Provide quantitative framework for the surface
  and groundwater exchanges
• Determine influent / effluent nature of levied
  section
• Quantify river losses
• Identify seasonal patterns
• Estimate alluvial aquifer recharge

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SW/GW Overview
Water flows from the stream into the subsurface
Water flows from the subsurface into the stream
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Methods

• Chemical Signature
• Mini-piezometers
• Temperature profiling
• Ditch loss

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Chemical Signature Requirements

• Conservative and naturally occurring
• Chloride and Sulphate
• GW/SW must have distinctly different
  concentrations
• Ease of analysis
• Ion chromatography

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Chemical Signature

• Grab Sampling
• Mainstem Walla Walla River
• Shallow aquifer wells
• 10 duplicate sampling
• Data Analysis
• Mixing space diagrams
• Linear Regressions
• Mass Balance

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Chemical Signature Mass Balance
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Groundwater Sampling Sites
Red dots are wells
Hwy 11
Tumalum Bridge
Walla Walla River
Nursery Bridge
Milton-Freewater
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In-Stream Sampling Sites
Tumalum Bridge
Nursery Bridge
Milton-Freewater
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Mini-Piezometers
Vertical Hydraulic Gradient dh/dl
Stream surface
dh

Streambed surface
dl
Mid-point of perforations
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Temperature profiling device
Mini-piezometer
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Temperature Profiling
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Temperature Profiling

• ?Analytical Methods
• HYDRUS-2D (Šimunek et al., 1999)
• Computer model using inverse processes to solve
  for vertical flux
• Sine Wave Fitting
• Stallmans (1965) equation for a sine wave fit to
  the data

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Temperature Profiling

• HYDRUS-2D
• Sophocleus (1979)

Conduction
Convection
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Temperature Profiling

• Sine Wave Fitting
• Stallman (1965)
• Solution for diurnally heated and cooled boundary
  condition

Tz (t) ?T e-az sin (2pt/t bz) Taz
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Temperature Profiling No Flux
HYDRUS-2D no flux simulation R2 0.95
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Ditch Loss Study
Installed dam Covered with plastic
Allowed to fill to capacity Shut off water
supply Measured time and depth of draining for 6
hours
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Chemical Signature GW
R2 0.89
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Chemical Signature SW
R2 0.96
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Chemical Signature Mass Balance
Filled symbols correspond to left axis, open
symbols correspond to the right axis
GW dominates
Tumalum Bridge
SW dominates
Qgw
Qsin
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Mini-piezometers
Nursery Bridge
Tumalum Bridge
duplicates
duplicates
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Temperature Profile
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Temperature Profiling Sine Wave
M 5.5 August 14
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Temperature Profiling HYDRUS-2D
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Temperature Profiling Sine Wave vs. HYDRUS-2D
Pink are results using loggers 3 to 2 (15
cm) Blue are results using loggers 3 to 1 (30 cm)
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Mini-piezometers
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Seasonal Patterns Mini-Piezometers
K -Q / (A dh/dl)
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Seasonal Patterns Temperature
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Ditch Loss

• Infiltration estimate 204 cm/d

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Conclusions

• Effluent river on section studied
• Estimated flow loss
• 0.3-0.76 m3/s using temperature estimates
• 0.43-0.63 m3/s using in-stream flow measurements
• Seasonally hydraulic conductivity decreased
• factor of 2-4 using temperature profiling
  estimates
• factor of 2-100 using mini-piezometer estimates

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Implications for GW recharge of the shallow
aquifer

• Assuming only 50 km of ditches with an average
  infiltration rate of 204 cm/d
• 2 107 m3 / yr
• On an area of 538 km2 and a porosity of 0.27
  equivalent to 23 cm of water
• Assuming 5 months at max infiltration rate of
  310 cm/day using temperature profiling estimates
• 1.8 108 m3 / yr
• On an area of 538 km2 equivalent to 1.2 meters of
  water

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Future Work

• Determine seasonal patterns in aquifer levels
• Continual static level measurements
• Installed pressure transducers in 12 wells
• Chemical signature
• Spatial mapping of anion concentrations
• Ditch loss studies
• Inflow out flow measurements
• Temperature profiling of ditch bed
• Evapotransporation
• Area of influence of infiltration from the river
• Instrument a transect across the entire levy
• Leave devices in place for the entire season

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Thanks to

• WWBWC and OWEB for caring enough about the
  watershed to fund this project
• Bob Bower for EVERYTHING!
• Community in the Walla Walla Watershed
• John Selker for tireless enthusiasm and myriad of
  good ideas
• Emilie Baer for her hard work in the field and in
  data analysis
• My committee Julia Jones, Jeff McDonnell, Roy
  Haggerty, and Mike Gamroth
• OSU Bioengineering Department
• June Rice, Elena Maus, David Rupp, Kristy
  Warren, Ruth Boitz, Linda Hoyser
• Friends and Family for continual support
• Especially thanks to Jeff Silvis for still
  becoming my husband even after the trials and
  tribulations of moving across the country and
  graduate school.

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