This document discusses insights and blind spots related to integrated modeling. It notes that traditional modeling approaches have "simplified" interactions between hydrology, hydraulics, and hydrogeology, creating blind spots. True integration requires addressing these blind spots early in modeling. The document provides examples of common blind spots like assuming groundwater and surface water are separate, and discusses how new research shows they are more interconnected through things like the shallow subsurface critical zone. True integrated modeling considers the full interaction of hydrologic and hydrogeologic processes.

1. 1
Integrated Modelling:
Insights and Blind Spots
Dirk Kassenaar
Earthfx Inc.

2. 2
Blind Spots
► “The only thing worse than being
blind is having sight but no vision”
Hellen Keller (1880-1968)
► We all have a blind spot at our optic
nerve connection.
 Your blind spot is only 20 degrees off
your main center of vision line!
 Our brain “post-processes” it away.

3. 3
Modelling Blind Spots
► Why are blind spots common in integrated modelling?
 Each discipline (Hydrology, Hydraulics and Hydrogeology) has
traditionally “simplified” the others in order to solve their problems.
 Those simplifications become blind spots when developing an
integrated model
► The temptation is to defer addressing the blind spots until
an “integration” phase late in the model development
project.

4. 4
Insights and Blind Spots
► The only thing worse than being blind is having sight but no vision”
► Blindness: Uncoupled modelling
 Historic simplifications prevent us from true understanding
► Sight: Integrated modelling
 Better, but not enough if historic blind spots are not addressed
► Vision: Knowing where to look
 Insights are usually located in the blind spots
 Integrated modelling starts at the conceptualization phase
► Know, and address, the blind spots early in the modelling process

5. 5
Earthfx SWP Fully Integrated Models
► Every project is an opportunity, for
both the client and consultant
► Our goal at Earthfx was to
complete Tier 3 studies using the
best available modelling technology
► We would like to thank our SWP
clients for their vision.

6. 6
Model Selection
► Blindness: My code is better than your code
 My code is fully-integrated, fully distributed, physically-based, multi-
processor, open-source with fully-automated parameter-estimation
and a “use-friendly” interface.
► Insight: The difference between model codes is generally
less important than the skill and vision of the modelling team
 Insight: All integrated models work in humid glacial terrain
 However: Mackay Watershed: 70 percent of the study area is muskeg
on discontinuous permafrost (need a good frozen ground module).

7. 7
GW/SW Partitioning
► Blindness: Attempting to quantify and partition the GW and
SW components of flow
► Insight:
 Water does not care what we call it: Stop trying to classify it and put
it into fixed buckets.
 Water moves seamlessly and continuously between domains
 Anything we do in the watershed will move water from one bucket to
another in any case….

8. 88
Aquifer Head vs. Stream Stage
• GW/SW discharge
reverses during
each storm event
• Baseflow
separation?
Good luck..
• GSFLOW Simulated Hydrograph at Oro-Hawkstone stream gauge
Storm Event Reversal:
Stream level higher than aquifer
Dry period:
Aquifer level higher than
stream = GW discharge

9. 9
GW Recharge
► Blindness: GW Recharge rates are strongly correlated with
surficial geology
► Insight: Groundwater feedback dominates
 Surficial geology is important only where there is no GW interaction
► E.g. the top of the ORM
 GW feedback dominates event runoff response
► Even the SW modellers think so: They referred to the “contributing area”
to understand event response
 Attempting to estimate recharge without assessing fluctuating water
table feedback is nearly impossible.

10. 10
GW Feedback: Dunnian Runoff
► Runoff that occurs off fully saturated soils
 Occurs when the water table is at or near surface
 Not sensitive to surficial material K
► Can create runoff from saturated gravels
 Spatially controlled: Tends to occur in stream valley areas
 Seasonally controlled: Tends to occur in spring when WT is high
► Not sensitive to rainfall intensity or model time step
Unsaturated
zone
StreamStream
Gravity drainage
Recharge
Ground-water flow

11. 11
How common is Dunnian Runoff?
► Portions of York Region where Dunnian rejected recharge occurs
 Depth to water table less than 2 m
 Also on ORM south flank: flowing wells, springs and headwater seeps

12. 12
Surface Discharge and Time-varying GW Feedback
► The “contributing area” that
generates true runoff
depends on the time-varying
position of the water table
► Milton Tier 3: Dunnian
response area varies
seasonally between 5 and
25% of the watershed area

13. 13
Unsaturated Flow
► Blindness: The SW and GW systems are linked by 1-D
vertical flow through the unsaturated zone.
► Insight: A singular focus on the “unsaturated zone” is wrong
 New Runoff Conceptualization: Event mobilized GW discharge
 New research focus: “The Critical Zone”
 New models: MODFLOW-NWT: Designed specifically for the
simulation of shallow interface flow

14. 14
Trouble: The “Old Water Paradox”
► Hydrologists are re-evaluating basic SW processes
 Jeff McDonnell, 2011 Birdsall-Dreiss Lecture
Rainfall Event
Increase in Streamflow
Deuterium isotope profile shows that
event streamflow is predominantly
“old” water (i.e. water that has been
subject to ET processes)
Conclusion: Storm event
streamflow is mobilized shallow
groundwater!
Time

15. 15
More Trouble…
► Garth van der Kamp, Research Scientist (Groundwater and surface
water interactions), National Hydrology Research Centre, Saskatoon, SK
► Slide from Garth’s IAH 2012 World Congress Keynote Presentation:
► Conceptual flownet
models are wrong –
fail to recognize
exponential
decrease in K
► Active flow in the
shallow zone
dominates
► Agreement with the
event mobilized
groundwater theory

16. 16
NSF “Critical Zone” Conceptual Model
► In 2001 the US National Science Foundation (NSF) began
work on a new “framework” for shallow earth science
research
 More comprehensive approach than just GW/SW, unsat flow, etc.
 Includes water, climate, vegetation (carbon cycle), energy processes
► New terminology: the “Critical Zone”
 Definition: “where rock meets life”
 “From the tops of the vegetation down into the groundwater”
► NSF funding of “Critical Zone Observatories” (CZOs)
 Multiple research sites set up to study CZ processes
 http://www.criticalzone.org

17. 17
NSF “Critical Zone” Research Approach

18. 18
Critical Zone Conceptual Model
► Macropores
► Interflow!!
► Throughflow
► Event mobilized GW
► Soil/rock contact zone
interface flow
► Seepage faces
► 1D Richard’s eqn.
unsat flow?
► 2D Diffusive wave
runoff?
from Lin, 2010

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Integrated Modelling is Different
► Integrated modelling forces us to address the blind spots (assumptions
and simplifications) we make about the “other” (SW or GW) system
► Integrated modelling is better for GW modelers, because:
 It allows the use of measured fluxes (precip and total streamflow)
 Forces us to fully address transient response, storage and the wide range of
GW flow rates
► Integrated modelling is better for SW modelers, because:
 Storm response (runoff generation) can be include water table feedback and
event mobilized shallow system storage
 Integrated modelling is physically based and distributed (no “lumped”
parameters)

20. 20
Next: Integrated Modelling at the Engineering Scale

21. 21
Flow
Schematic
between
multiple
excavations
21
(With Average
Takings)
11,175 m³/day
4,048 m³/day
10,675 m³/day

22. 2222
Overland
Flow
Simulation
(With Average
Accumulating
Overland Runoff)

23. 23
Integrated Assessment of Offsite Discharge
► Whether it is GW or SW discharging from the quarry pit does not matter
► Integrated assessment:
 No blind spots or pre-conceived assumptions
 No need to partition the assessment of impact

24. 24
Conclusions
► Integrated Modelling is different; It requires:
 Integrated data management
► Data silos and barriers will only hide the relationships and response lag
between the systems
► You cannot build an integrated model without an integrated database
See: Sitefx 6.0 and VIEWLOG 4.0
 Integrated Conceptualization: Start now.
 Integrated calibration
► Don’t become attached to your initial uncoupled calibration estimates!
► Consider re-conceptualization, even late in the integrated calibration
 An integrated and balanced modelling team
► The skill, multi-disciplinary knowledge, and ability of the SW and GW
experts to address their “blind spots” is far more important than the
choice of model code

25. 25
Integrated Modelling: Final Insight
► Blind Spot: Process flow
charts are a good way to
communicate the concepts of
integrated modelling
► Insight: FAIL
 A good conceptual cartoon
always helps
 Look at those clouds!