Dusting Off the Source Water Protection Models: Adaptation and Application of Existing Models to New Projects

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Dusting Off the Source Water
Protection Models:
Adaptation and Application of Existing Models to
New Projects
M. Takeda, P.J. Thompson,
Dirk Kassenaar, E.J. Wexler
Earthfx Incorporated, Toronto, Ontario, Canada
Presented by
Michael Takeda
Earthfx Inc.

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1) Introduction
2) Source Protection Plan
3) The Role of Numerical Models
4) Opportunities for Model Re-Application
5) Consideration of Limitations
6) Closing Summary
Dusting Off the Source Water Protection Models:
Adaptation and Application of Existing Models to New Projects 2
Presentation Outline

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Source Water Protection
Walkerton Tragedy
► E.coli in municipal drinking water supply.
► 7 people died, 1000’s became ill
► Traced to runoff from farm discharging to
wetland
► As a result, Clean Water Act was introduced
which required Source Water Protection
Studies to be undertaken across Ontario
► Water Quality Assessment
► Water Quantity Assessments

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Source Water Protection Studies
Tier 1 Water Budget Studies
► Screening level studies to identify “stressed watersheds”
(total use > 25% of available water)
► Numerical models to confirm watershed stress analysis
► Detailed integrated groundwater and surface water modelling
"The first barrier to the contamination of drinking water
involves protecting the sources of drinking water."
Justice Dennis O'Connor (2002)
► Assess “water quantity threats” to municipal water supply using a tiered approach.

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Integrated GW/SW Models
Integrated Models:
• Represent hydrologic system,
groundwater system, and
interactions between them

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The Role of Numerical Models
Earthfx Detailed Water Budget
Studies
► Five Tier 3 Source Water Protection Studies:
 (Four complete, one starting up)
► Two Lake Simcoe Protection Plan Studies
Multi-watershed Scale
► Attempts to explain the transient movement
of water though the surface and subsurface
systems on a watershed scale.

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Presentation Objective
What are the potential opportunities for further
application of the Drinking Water Source
Protection Models?

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Opportunities for Model Re-Application
Ecologically Significant
Groundwater Recharge
Areas (ESGRA)
Analysis
Assessment of Impacts
of Large Scale Urban
Development
Climate Change
Assessment
Pit and Quarry
Applications

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ESGRA Analysis
What is an ESGRA?
► ESGRAs are identified as areas of land that sustain sensitive features like cold
water streams and wetlands.
► Not related to volume of recharge; rather they are linked by pathways through
which GW recharge reaches a given feature.
► ESGRA analysis is an ideal application to understand flow system linkages and
volumetric recharge (in a relative sense).
SGRA vs ESGRA?
► SGRAs are “areas where the rate of recharge is greater than a factor 1.15 of
the average recharge across the area”. [1]
► Based on amount of recharge volume, not specific flow systems and linkages.
► SGRAs have potential to miss areas of local significance.
[1] Ontario Ministry of Environment, 2009, Technical Rules: Assessment Report, Clean Water Act (original release 2006).

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ESGRA Analysis
► Establish a linkage between a recharge area and environmental
feature - Pathway exists through the groundwater system

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1
ESGRA Analysis: Approach
► Step 1: Model Construction:
 Hydrology: Need to simulated wetlands and streams. As
well as best estimate of recharge and runoff.
 Hydrogeology: Need detailed simulation of the shallow
subsurface.
 Scale and structure of model should be appropriate for
target(s) of analysis.
Focus of Discussion:
► Use Particle Tracking to link eco-features to recharge areas.
► Use cluster analysis to identify particle endpoint groupings and
significance.

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Adaptation and Application of Existing Models to New Projects
ESGRA Analysis: Particle Tracking
► Particles released in the
wetland (green area)
► Particles tracked backwards
through the flow system
► Black dots show endpoints
where GW recharge
occurred
► Select red lines illustrate
flow paths from wetland to
recharge area
► In this case, the wetland
received recharge from
three areas
Example of backward particle-tracking from a significant feature
(Bluffs Creek West Wetland, Oro Creeks North Subwatershed)
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ESGRA Analysis: Particle Tracking
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(Examples from CLOCA ESGRA Study 2014)
Bowmanville Creek –
Hampton Branch
Harmony-Farewell Iroquois Beach
Wetland Complex
Backward Tracking Endpoints

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ESGRA Analysis: Cluster Analysis
► Need for a defensible methodology to delineate Ecologically Significant
Groundwater Recharge Areas (ESGRAs).
► Methodology is objective, unbiased, and consistent
► Also, transferable for use in other study areas.
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ESGRA Analysis: Cluster Analysis
► ESGRAs are areas of relatively high particle endpoint density
 Endpoint density is assumed to represent largest contributors of recharge to
ecological systems of interest.
► Assume each pathline endpoint is representative of a normally distributed
recharge feature.
► Kernel density processing converts endpoints (black dots) into a continuous
“Cluster frequency distribution”
► Optimal values determined through sensitivity
analysis.
𝑓𝐻 𝑥 =
1
𝑛ℎ 2𝜋
𝑒
−
1
2
𝑑 𝑖
ℎ
2𝑛
𝑖=1
15

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► Particle tracking is a powerful means to link the recharge area to
features of interest and therefore assign eco-significance.
► Particle tracking provides visual insights into both the shallow and
deep flow system.
► The methodology is automatic, objective, unbiased, consistent, and
transferable for use in other study areas and different models.
 The function is independent of how the particle end points are generated.
 This makes it an ideal application for existing Source Water Protection
Models.
 Analysis can be relatively inexpensive.
► Extends insights and understanding of hydrologic/hydrogeologic
system from previous modelling work to focus on specific features of
interest and/or conservation objectives.
ESGRA Summary
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Areas (ESGRA)
Analysis
Development
Climate Change
Assessment
Pit and Quarry
Applications
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Climate Change Analysis
► The Water Budget drought assessment component of the Source Water
Protection program has driven the analysis of water supply
sustainability in Ontario.
Study
watersheds
► Simulation of recent droughts provides
an excellent foundation for climate
change analysis.
 Insights into the complex behaviour at both
the watershed and tributary scale
 An excellent “stress test” for the model
 A good understanding of the system, and a
framework for climate change assessment.
► Conducted using the integrated
GSFLOW Ramara-Whites-Talbot Model
built for the LSPP water budget
drought assessment.
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► Many different climate models exist with range in predictions.
In general:
► 2 to 4C temp. increase by 2050.
 About double the global estimate.
► More extreme warm temp
expected (versus mean annual
temp changes)
 More heat waves and droughts.
► Annual precip will increase up to
10% in S. Ontario, but
 Summer and fall total rainfall may
decrease by up to 10%,
 Winter precip may increase up to 10% in south,
 Less precipitation as snow; more lake effect snow, and
 Rainfall intensity and frequency of intense events to increase.
Climate Change in Ontario
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Climate Change Analysis
► Applied the recommended approach “Change Field Method” as per
MNR guidelines (EBNFLO & Aquaresources, 2010).
► Infilled hourly CC data available through the Aquamapper website
(climate.aquamapper.com).
► Hourly simulations spanning 29-years were completed for 10
scenarios.
► Hydrologic/hydrogeologic impacts assessed based on GSFLOW
model outputs.
► All results equally valid.
► Step 1: Model Construction:
 Integrated model needed to capture interactions between GW/SW
system during climate change scenarios.

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Climate Change Inputs
► Shift in Monthly Temperature
◄ Shift in Monthly Precipitation

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Climate Change Results – Snow Depth

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Climate Change Results - Streamflow
► Reduced snow depth in winter due to increased rainfall (temps).
► Depletes reservoir for spring freshet.

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Climate Change Results - GW Recharge
► Reduced snow depth in winter due to increased rainfall (temps).
► GW recharge is similarly affected (dampened).

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Climate Change Results
Drought Period
► More flow in winter months
► Spring freshet is earlier
► Less sustained groundwater recharge
► Reduced drought resilience

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Climate Change Results
Drought Period
► Results were sensitive to underlying geology
► Streams fed by aquifers with higher storage are more resilient to
drought under climate change
Drought Period

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Climate Change Analysis: Summary
► Linking the climate to the geology is required to understand how
storage and the connection to subsurface affects streamflow
► Understanding how the subwatersheds and specific stream reaches
respond to drought (which is more extreme) helps inform mitigation
and adaptation strategies moving forward
► Integrated models built for drought or low flow analysis are well suited
for climate change assessment.
 Logical extension of the SWP program work.
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Areas (ESGRA)
Analysis
Development
Climate Change
Assessment
Pit and Quarry
Applications
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Large Scale Urban Development
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Proposed Site Plan
► Complex stormwater
management plan
► Compare Current and
Post-development
conditions
► Analyze changes to
groundwater recharge,
runoff, and wetland
hydroperiod
► Evaluate goal of storm
water management
system: to restore more
“natural” conditions

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► Model was developed to assess impacts of the proposed development
on water budget elements.
► Objectives, scale, methodology has many similarities to Source Water
Protection studies:
 Integrated GW/SW model simulating transient response to seasonal and
year-to-year variation (similar to Tier 3 Assessment).
 Regional scale to represent hydrologic system.
 Comparison of post-development and
current conditions to evaluate impacts of
development.
► Simulation of small-scale design elements
(stormwater management infrastructure)
was critical to the assessment.

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Impacts on Wetland Stage
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Current Simulated
Hydroperiods
Post-Development
Simulated Hydroperiods

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Impacts on Wetland Stage
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Natural, Current Conditions, and Post-development

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► Transient Model results
showing behaviour of system
under current conditions.
► Figure shows:
 Precipitation
 Groundwater heads
 Streamflow
 Lake & Wetland Stage
► Tier 3 models represent
regional-scale understanding
of hydrologic/hydrogeologic
setting
 Can be used to address
local-scale problems
Click for Animation

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Areas (ESGRA)
Analysis
Development
Climate Change
Assessment
Pit and Quarry
Applications
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► Application for pits and quarries
requires evaluation of potential
impacts to other stakeholder (as
per Aggregate Resources Act,
Planning Act, etc.).
 Groundwater and surface water.
 Ecological features and
communities.
 Quarry geometry and infrastructure
can be successfully incorporated
into a model – Why not a Tier 2/3
model?
Pits and Quarry Applications
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► They can be some of the
most prominent features
in the watershed!
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► Permits can be listed as surface water only, groundwater only, or mixed
groundwater-surface water taking.
► But realistically – they are both.
► Evaluating potential impacts of quarries should reflect this.
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► Also have water management
infrastructure.
► Can be highly transient and complex.
 Let fill during winter?
 Process Takings?
 Siltation Ponds?
 High-flow bypasses?
► What are the impacts of these
operations on natural system?
 Seasonally?
 In a drought?
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► Use a passive system
representation.

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Passive System Representation
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► Ditching that drains both groundwater and surface runoff from
topographically controlled cascade.
► Sumps that collect ditched water and control groundwater heads.

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Simulated and Observed
Quarry Discharge

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► It’s difficult to assess impacts of proposed and existing pit and quarry
operations on GW/SW resources and ecological features.
► Represent alteration of both hydrologic
and hydrogeologic systems.
► Source Protection Models are developed
with groundwater/surface water
interactions in mind –
as well as regional perspective on
hydrologic system
Pits and Quarry Applications - Summary
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Water
Management
Climate
GW/SW
System

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► A model is developed to solve a specific problem.
► The ability of the model to solve a new problem depends upon:
 the relatedness of that problem to the original purpose of the model; and
 the versatility of the model itself.
► Limitations of the models and scope of the proposed application must
always be taken into consideration, and – when required – addressed.
 Boundary Conditions
 Grid/Mesh Refinement
 Layer geometry and parameterization etc.
► Ultimately, model needs to be capable of solving the question being
asked.
Consideration of Limitations
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► Numerical models have been a vital tool in meeting the requirements
of the Drinking Water Source Protection Program.
► Represent extensive work consolidating knowledge and understanding
of various hydrologic and hydrogeologic process in each of the study
watersheds.
► Value of these models can extend beyond initial SPP objectives with
continued adaptation and re-application to new studies:
 ESGRA Analysis
 Climate Change Assessment
 Assessment of Impacts of Urban Development (and mitigation
alternatives)
 Pit and Quarry Applications
Closing Summary
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Thank you

Dusting Off the Source Water Protection Models: Adaptation and Application of Existing Models to New Projects

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