utilizing natural thermal signals to assess advantages of using heat as a tracer •workflow...

Matrix Solutions Inc. 1

Utilizing Natural Thermal Signals to Assess Groundwater – Surface Water InteractionsNelson Molina Giraldo and Paul Martin

WaterTech 2017 – Banff, Alberta – April 2017


GW-SW Interactions

Time

GW

-SW

inte

ract

ion


GW-SW Interactions


Existing Approaches to Measure GW/SW Interactions

• Direct measurements of water flux

o Seepage meter

• Darcy‘s Law Approach

o Hydraulic gradient (piezometers)

o Hydraulic conductivity (pumping test, grain size, etc.)

• Mass balance approaches

o Incremental streamflow

o Hydrograph separation

o Environmental tracer methods

• Natural fluctuating physical properties

- Electrical conductivity

- Heat as a tracer


Overview

• Use of natural temperature variations to infer groundwater – surface water interactions

• Advantages of using heat as a tracer

• Workflow

• Case study


Use of natural temperature variations to estimate groundwater – surface water interactions

Part 2


Natural Temperature Signals

Diurnal temperature signals

Seasonal temperature signals

Summer

Winter

Day

Night


Propagation of Temperature Signals

• Thermal parameters

• Frequency (e.g., diurnal, seasonal)

DA

Df

Streambed


Streambed




DA

Df

• Vertical groundwater velocity



Observation well

Molina Giraldo et al. 2011


Computation of Vertical GW Velocities

Streambed

Vertical Groundwater

velocity?


Computation of Vertical GW Fluxes

The following expression derived from equation (6) describes the vertical Darcy flux in terms of the amplitude attenuation and time lag at two measurements points (Luce et al. 2013 and Gariglio et al. 2013):

*vvC

Cd

w

mz

q

1

1

2

1*vTd fDv 4

12

12ln

ff

AA

f D

D

12

2zwDT


Computation of Vertical GW FluxesRaw Temperature Time Series

Sensor at 0.0 mSensor at 0.2 m

Sinusoidal Components

Time Lag

N

i

ii

tit

tittAtT

1

0 2sin)(2cos)()()(

)()()( 22 tttA iii

)(

)(tan)( 1

t

tt

i

ii

f

Captain Toolbox – Dynamic Harmonic Regression


Advantages of Using Heat as a Tracer

Part 3



• Tested/Applied in Several Locations

• High resolution (hours)

• It responds to stresses

• Low impact Installation/Instrumentation

• Continuous monitoring



We can better constrain the estimation of GW/SW interaction

s

Q

River

OBS

s

Q OBS

s = 0.4 m

s = 0.1 m

TheisSolution



Aquifer

T °C

River

Aquitard

Unsaturated zone

Natural temperature variations are intrinsic to the system

No need to induce additional tracers


Workflow

Part 4


Workflow

MATRIX FLUX TOOLBOX

Data Review and Editing Tool

Field Data


Workflow

Field Data


Workflow

Data Review and Editing Tool


Workflow

MATRIX FLUX TOOLBOX


Case Study

Part 5


Stakeholders Concerns

• Thermal project designed so that there is relatively low likelihood of impacting surface water flow, however…….

• Stakeholder have asked difficult questions:– What is the magnitude of gw – sw interaction due to groundwater

withdrawal?

– Will other project related activities alter groundwater discharge to/from streams?


Our Approach

• Focused approach for measuring the change in flux between groundwater and surface water over time.

• The underlying rationale for the proposed monitoring approach is that any changes in groundwater-surface water flux is most likely to be identified by monitoring temperature signals in the streambed and shallow sediments.


Instrumentation Set up


Fluxes Over Time

Monitoring Site ASatellite Imagery


Fluxes Over TimeMonitoring Site A Monitoring Site B


Impacts from GW Use

Monitoring Site A


Summary

1) Heat can be used as a tracer to estimate groundwater – surface water interaction and itis well understood

2) There are advantages over other methods of characterizing GW-SW interaction– Intrinsic to the system–More precise estimation of GW/SW interaction

compared to pressure measurements alone.

3) The method has effectively been applied several locations to address stakeholder concerns


Questions?

Nelson Molina Giraldo

[email protected]

Paul Martin

[email protected]

mailto:[email protected]

mailto:[email protected]

utilizing natural thermal signals to assess advantages of using heat as a tracer •workflow...

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