Applications of Integrated Models to Watershed and Sub-Watershed Scale Analysis: A Canadian Context

Applications of Integrated Models to Watershed and Sub-
Watershed Scale Analysis: A Canadian Context
E.J. Wexler, P.J. Thompson, J.D.C. Kassenaar, M. Takeda
Earthfx Incorporated
XXI International Conference Computational Methods in Water
Resources, June 2016

Watershed-Scale Integrated Modelling in a Canadian Context
Historical Perspective: Ontario
 1990 – 2000
▪ Groundwater models rarely used for engineering design or
impact assessment. Simple water budgets and aquifer tests
 2001-2003
▪ Steady state groundwater models for Ontario Municipal Groundwater
Studies and some quarry impact studies
▪ After Walkerton disaster, Source Water Protection called for multi-
tiered assessment of watersheds and municipal supply
 2003 – Present
▪ Loosely-coupled hydrologic/groundwater models for Tier 2 and 3
 Key questions at Tier 3 level:
▪ Impact of municipal wells on wetlands and coldwater streams
▪ Impact of drought on municipal wells
▪ Impact of future development on groundwater recharge
▪ We developed 7 integrated models for Tier 3 watershed assessments
to answer these questions
2- History in Ontario/Canada
CMWR
2016
Integrated
Watershed
Models by
Earthfx

Integrated Models: Canadian Applications
 Watershed Management
▪ Water Budgets (Current/Future)
▪ Source Water Protection
▪ Irrigation demand management
▪ Ecological Flow Needs
 Land Development
▪ Cumulative impact of development
▪ Low Impact Design alternatives
 Resource Extraction
▪ Quarry/Mine impact
▪ In-Situ oil sands development
▪ Mine-site management
 Climate Change Adaptation
3- Model Applications

Integrated Models
 Integrated models consider both groundwater and surface water flow.
 Feedback between the two systems can dominate in some hydrologic settings
 For example, shallow water table influences:
▪ Evapotranspiration rates
▪ Dunnian (saturation excess) runoff
▪ Key for representing groundwater interaction with streams,
lakes, and wetlands.
4- Definitions
Unsaturated
zone
StreamStream
Gravity drainage
Recharge
Ground-water flow
Interflow
ET
Dunnian Runoff

USGS GSFLOW Code
 Many integrated modelling codes
 We use the USGS integrated GSFLOW code
for watershed and engineering-scale studies:
▪ Open-source, proven, and very well documented
▪ Combines two USGS models: MODFLOW and
PRMS (Precipitation-Runoff Modeling System)
▪ Fully-distributed: cell-based representation of
hydrology and groundwater
 Good balance of hydrology, hydraulics, and
groundwater flow
5- GSFLOW

GSFLOW: Multi-Resolution
6
Climate inputs
(Gridded or by gauge)
Hydrology/Soil Zone
(PRMS HRUs)
Hydrogeologic Layers
( MODFLOW finite-difference grid)
Stream Network
1-D Channel segments
- GSFLOW
MODFLOW-NWT

Watershed-Scale Integrated Modelling
in a Canadian Context
CASE STUDY 1:
ORO MORAINE
7- Case Study 1

Oro Moraine: Geologic Setting
 Three subwatersheds discharging to
Lake Simcoe
 Oro Moraine is a high-recharge feature
 Feeds wetlands and headwater streams
 Model boundary expanded to
encompass all Moraine-fed watersheds
 Complex geology – best seen in
section
8- Oro Moraine
Oro Moraine
Model Boundary
Study sub-
watersheds

Oro Moraine: Geologic Setting
 Multiple tills
and sand
layers
 Cut across by
“tunnel
channels”
9- Oro Moraine
Oro Moraine
Tunnel Channel
occupied by
Cold Water Creek
Lake
Simcoe

Oro Moraine: Hydrology
 GSFLOW model represents all stream segments,
lakes, and wetlands
 Calibrated to daily and monthly flows at four
stream gauges
 Validated against historical low flow periods
10- Oro Moraine
Coldwater Creek
(02ED007)

Oro Moraine: Groundwater
 Shallow system show influence of topography and
streams.
 Calibrated against over 3400 static water level
measurements
 Fewer (10) transient monitors
 Transient model matches seasonal patterns
11- Oro Moraine

Oro Moraine: 10-year Historical Drought
 Used daily climate data from 1956-1967
drought to analyze subwatersheds response
 Drought sensitivity depended on
whether streams were linked to Oro
Moraine or recharged locally
12- Oro Moraine
1953-1967
Low
High – Tribs
Low - Main
High

Oro Moraine: Groundwater Pathways
 Particle tracks
show shallow and
deep flow systems
 Oro Moraine
mainly feeds
streams and
wetlands on flanks
 Geology influences
stream/aquifer
interactions
 Deep flow system
feeds distant
features
13- Oro Moraine

Oro Moraine: Climate Change
 Sampled a range of
GCMs.
 Used results to scale
baseline T and precip.
 Ensemble of climate
simulations show:
▪ Earlier spring freshet
▪ Reduction in summer flows
due to low summer rainfall
and longer recession.
14- Oro Moraine
Jan Y1 Jan Y2 Jan Y3
Note log scale for flow
Flow versus Time - Oro South

Oro Moraine: Climate Change
 Integrated models useful
for predictive analysis
 Important Factors:
▪ Underlying geology
▪ Connection to regional high
recharge features
▪ Storage
 Drought-sensitive
watersheds tended to
be more sensitive to
climate change.
 Click for Animation
15- Oro Moraine
Baseline CGCM3T63

CASE STUDY 2
CUMULATIVE IMPACT OF
IN-SITU OIL SAND
DEVELOPMENT
16- Case Study 2
From MEG Energy Corp.

MacKay Watershed: Setting
 Watershed features:
▪ 600 m of topographic relief
▪ Incised rivers and streams
▪ Over 100 lakes
▪ Extensive muskeg and wetlands
 Numerous oil sands operations
▪ Open Pit and In-situ Steam Assisted Gravity
Drainage (SAGD)
▪ Water takings from both surface water and
groundwater (diversions)
▪ Clear cutting, well pads, roads, and
processing facilities affect recharge/runoff
 Model to assess future impacts of
expanded SAGD operations
17- MacKay Watershed
Ells River
Athabasca River
AthabascaRiver

MacKay Watershed: Hydrostratigraphic Model
After AGS Source: Andriashek and Atkinson, 2007
McMurray
FM
Oil Sands
Grand Rapids aquifer
Viking aquifer
Empress Channel Sands:
Key water supply aquifer

MacKay Watershed: Overland Flow
 Overland flow (runoff/runon) and
interflow simulated with a topographically-
controlled cascade network

MacKay Watershed: Wetland Classes
 Most of area covered by muskeg
 26 wetland and vegetative cover
classes used to parameterize the model
 Mapping by Ducks Unlimited. (Even in
the middle of nowhere, good datasets
can be found!)

MacKay Watershed: Frozen Ground
 We noted large lag between freshet and
groundwater recharge
 Couldn’t match with existing model
 Added new frozen ground module for
GSFLOW
▪ GSFLOW is Open Source!
 Based on modified Stefan Equation
▪ Derived by the U.S. Army Corps of Engineers
 Model code follows Emerson (1994)
 Freezes from top; thaws from top and
bottom
𝑋𝑓 =
86,400𝐾𝑓 𝐼𝑓
𝐿 + 𝐶 𝑇𝑎 +
𝐼𝑓
2𝑡
0.5
𝑋𝑓 = 𝑑𝑒𝑝𝑡ℎ 𝑜𝑓 𝑓𝑟𝑜𝑠𝑡
𝐾𝑓 = 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦
𝐼𝑓 = 𝑓𝑟𝑜𝑠𝑡 𝑖𝑛𝑑𝑒𝑥 𝑑𝑒𝑔𝑟𝑒𝑒 𝑑𝑎𝑦𝑠
𝐿 = 𝑙𝑎𝑡𝑒𝑛𝑡 ℎ𝑒𝑎𝑡
𝐶 = 𝑣𝑜𝑙𝑢𝑚𝑒𝑡𝑟𝑖𝑐 ℎ𝑒𝑎𝑡 𝑐𝑎𝑝𝑐𝑖𝑡𝑦
𝑇𝑎 = 𝑚𝑒𝑎𝑛 𝑎𝑛𝑛𝑢𝑎𝑙 𝑠𝑜𝑖𝑙 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒
𝑡 = 𝑑𝑢𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑟𝑒𝑒𝑧𝑖𝑛𝑔 𝑝𝑒𝑟𝑖𝑜𝑑
𝑤ℎ𝑒𝑟𝑒

MacKay Watershed: Frozen Ground
 Frozen soil dynamics affect both surface and subsurface processes:
▪ Observed high runoff during spring freshet; but no winter recharge
▪ Groundwater discharge to streams and wetlands reduced in winter
 Good match to observed with new module

MacKay Watershed: Model Calibration
200
300
400
500
600
700
800
200 300 400 500 600 700 800
Simulated(masl)
Observed (masl)
Overburden
Empress Fm.
Labiche Aquitard
Viking Aquifer
Joli Fou Aquitard
Grand Rapids Aquifer
Clearwater Aquitard
McMurray Aquifer/Aquitard
Cooking Lake Aquifer
1:1
Error Intervals (±10 m)
Static Water Levels
Daily Streamflow
 Daily Nash-Sutcliffe 0.65
 Monthly Nash-Sutcliffe 0.75
 Multiple steps: first as stand-alone models; then
as a coupled model
 Major advantage of GSFLOW, submodels can be
run separately
 Very little transient groundwater data

MacKay Watershed: PRMS Sub-model Results

MacKay Watershed: Future Scenario
 Baseline: No pumping
 Current Conditions:
▪ 4 Operations including 11 wells.
 Full-Build Conditions:
▪ 14 Operations including 42 wells.
▪ Drill pads are estimated to cover 6% of
the planned project areas;
▪ Roads, pipelines, and facilities cover
another 4%.
Current
Operations

MacKay Watershed: Groundwater Impacts
 Cumulative drawdowns are
significant, mainly in deeper
highly-confined aquifer units
 Drawdowns generally stable after
20 years, suggesting sustainable
water use
 Localized zones where drawdown
exceed 50% of total available
Viking/Pelican Aquifer
Layer 5 Drawdowns

MacKay Watershed: Impacts to Streamflow
 Evaluated simulated streamflows with
a number of environmental flow
criteria
 Impacts to simulated streamflow in the
major reaches is small
 Locally, some stream reaches are
severely impacted around large
diversions
▪ Shows that groundwater diversions mat
locally induce leakage that exceeds
ecological baseflow criteria
 Effectively determined by
integrated model

Case Study 3 – Wellfield Next to Reservoir
28- Milton
 Large wellfield directly adjacent to a
large flood control reservoir
 Transient integrated modelling
undertaken to analyze
the influence of reservoir
operations on wellfield
sustainability
 Identified previously
unknown linkages between
the wells and the surface
water system
 Simulation of the hydraulics was
critical! Click for Animation
Municipal Wellfield
Flood Control
Reservoirs
Transient Drawdowns

Case Study 4 – Mine Impact Assessment
29- Case Study 4
 Evaluated impact of future mine build- out
 Multi-watershed model, but with high
resolution around the mine site
 Model represented open pit, waste rock
stockpiles, drains, and tailings ponds
 Model simulated drawdowns and change in
streamflow from pre-mine conditions
 Click for Animation

Case Study 5 – York Region Water Budget
 Used an integrated model to assess
the sustainability of wellfields that
supply about 200,000 residents
30- York Region
CMWR 2016

Watershed-Scale Integrated Modelling in a Canadian Context 31- Case Study 5
Drawdown Impacts on Wetlands
Percent Decrease in Baseflow
Under Future Pumping
 Study looked at effect
of drought on wells
 Also looked at effect
of wells on wetlands
and coldwater streams
 Study showed that
streamflow affected
mainly within 1-m
drawdown line
 Few wetlands and
coldwater streams
remained within 1-m
drawdown
Case Study 5 – York Region Water Budget

CONCLUSIONS
32- Wrap Up

Challenges in Integrated Modelling
33- Wrap Up
 Calibration
▪ Good calibration is mandatory for predictive, engineering studies
 Model run times
▪ PRMS is fast but GSFLOW runs can take days
▪ Need faster MODFLOW solvers
▪ Better yet, need parallel solvers so models can run on multi-core machines
 Model stability
 Data limitations
▪ Continuous groundwater level and streamflow data can be sparse
 Staffing
▪ Integrated, multidisciplinary teams are a must!

Overall Conclusions:
34- Wrap Up
 Integrated models are effective, practical tools
to evaluate complex, challenging problems
from the watershed to the engineering scale
 Models provide insights for complex systems
 Canada is moving ahead in the application of
integrated modelling
 There are ongoing challenges, but transient,
integrated modelling is becoming the standard
for impact assessments, water budgets,
climate change predictions, drought
assessments, and eco-hydrology studies
 Click for Animation Thermal transport from a gravel pit lake

Questions or Comments? Click for Animation
35- Section Title

Applications of Integrated Models to Watershed and Sub-Watershed Scale Analysis: A Canadian Context

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