Assessing Cumulative Effects of SAGD Operations in the Mackay Watershed
Dirk Kassenaar, E.J. Wexler, P.J. Thompson, M. Takeda
Earthfx Inc.
CWRA 2016
Review of Cumulative Impacts – MacKay River Watershed
Introduction
In-situ Steam Assisted Gravity Drainage (SAGD) oil sand operations require a source of fresh water for steam injection.
Groundwater supply wells, generally drawing from aquifers above the oil production zone, are a preferred source.
2 - Introduction
From MEG Energy Corp.
Review of Cumulative Impacts – MacKay River Watershed
Study Objectives
In 2014, Earthfx Inc. was hired by the Cumulative Environmental Management Association (CEMA) to answer the following question:
▪ Is there enough water in the Mackay watershed to sustain a responsible level of oil sand development?
Cumulative effects analysis requires the integrated assessment of:
▪ Multiple anthropogenic stresses:
• Numerous spatially distributed SW and GW diversions
• Land use change (land clearing, drill pads, roads, etc.)
▪ Intersecting effects on surface and groundwater systems:
• Changes in groundwater levels (drawdowns) in all aquifer systems
• Changes to frequency, duration and severity of low flow conditions
3 - Introduction
Review of Cumulative Impacts – MacKay River Watershed
Study Area
MacKay River Watershed is located immediately north-west of Fort McMurray, AB ▪ Includes Syncrude Mine site and
numerous SAGD operations
Watershed Area: 5,600 km2
Model Area: 7,900 km2
4 - Summary of Model Development
Legend Lake
Namur Lake
Review of Cumulative Impacts – MacKay River Watershed
Study Approach
Step 1: Integrated Model Development and Calibration ▪ Model Development: Compile Geology, Hydrogeology, Climate, Hydrology, Hydraulics
▪ Model Calibration:
• Build and pre-calibrate the SW and GW submodels
• Complete the fully integrated model calibration: Full reconciliation of entire hydrologic cycle water budget
Step 2: Sustainability Assessment ▪ Define Assessment Criteria and Climate Period
• Define aquifer drawdown and streamflow impact sustainability thresholds
• Select a representative “surrogate” climate assessment period (25 years)
▪ Simulate Pre-development (Baseline), Current and Full Build conditions over the climate period
▪ Compare, on a daily basis, Current and Full-build conditions against Baseline
• Evaluate GW drawdowns and streamflow changes against Assessment Criteria
5 - Introduction
Review of Cumulative Impacts – MacKay River Watershed
Review of Cumulative Impacts – MacKay River Watershed
MODELLING APPROACH
6 - Modelling Approach
Review of Cumulative Impacts – MacKay River Watershed
Integrated Modelling Approach: Advantages
Study Approach: Fully integrated surface water and groundwater model
Better representation of: ▪ Groundwater recharge and
Dunnian GW feedback
▪ Streamflow and induced leakage
▪ SW/GW storage
▪ Cumulative effects of all SW and GW diversions
Flux inputs and calibration targets ▪ Measured precipitation as input
▪ Calibration to total streamflow and measured GW levels
7 - Modelling Approach
Review of Cumulative Impacts – MacKay River Watershed
Selected Model: USGS GSFLOW
USGS integrated GW/SW model ▪ Based on MODFLOW-NWT and PRMS (Precipitation-Runoff Modelling System)
▪ Open-source, proven and very well documented
▪ Fully-distributed: Cell-based representation
▪ Excellent balance of hydrology, hydraulics and GW
8 - Modelling Approach
Review of Cumulative Impacts – MacKay River Watershed
Review of Cumulative Impacts – MacKay River Watershed
SUMMARY OF MACKAY MODEL DEVELOPMENT
9 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Study Area Features
Topography (600 m of relief) ▪ Birch Mountains
▪ Thickwood Hills
Incised river and stream network ▪ MacKay River – main channel
▪ Dover and Dunkirk Tributaries
▪ Athabasca River: South and eastern boundary
Legend and Namur Lakes ▪ Plus over 100 other lakes in study area
Extensive muskeg and wetlands
Bedrock Channel Aquifers ▪ Key GW supply source for multiple projects
Anthropogenic Stresses ▪ Syncrude Mine
▪ SW and GW Diversions
10 - Summary of Model Development
AMBI, 2013)
Review of Cumulative Impacts – MacKay River Watershed
GSFLOW: Multi-Resolution
GSFLOW is unique in that the resolution of the model can be adjusted to match key features
11
Climate inputs ( 2.5 km cells)
Surface Hydrology/Soil Zone ( 200x200 m cells)
Sub-surface Hydrogeologic Layers ( 13 layers of 400x400 m cells)
Stream Network Linear 1-D Channel segments (4000 km of streams represented, independent of grid resolution)
- Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Model Grid
Fully distributed model: Every cell has unique properties
GW grid: 400 m by 400 m cells ▪ Selected to match assessment
averaging criteria (impact at 150 m from a well) but avoid focus on specific water users.
▪ Can be refined for future studies
SW Grid: 200x200 m cells ▪ Improved representation of overland
flow, wetlands, interflow and soil zone processes and properties
Stream routing: ▪ All streams and rivers simulated
12 - Summary of Model Development
400x400 m GW grid
Review of Cumulative Impacts – MacKay River Watershed
Geologic Setting
13 - Summary of Model Development
Surficial Geology Bedrock Geology
Predominantly tills and glaciolacustrine deposits
Subcrop of units that dip to the southwest
Review of Cumulative Impacts – MacKay River Watershed
Geologic Information
14 - Summary of Model Development
Primary sources for geologic borehole data:
25,000 - Alberta Geological Survey
255 - Atlas (Western Canada Sedimentary Basin)
Limited geologic data in Birch Mountains and central portion of study area
Review of Cumulative Impacts – MacKay River Watershed
Conceptual Stratigraphic Model
15 - Summary of Model Development
After AGS Source: Andriashek and Atkinson, 2007
Empress Channel Sands: Key water supply aquifer
Review of Cumulative Impacts – MacKay River Watershed
Hydrostrat. Layers
16 - Summary of Model Development
19 layer strat. model used to produce 17 layer hydrostrat. model. ▪ Some units of similar hydraulic
properties were combined.
▪ McMurray Basal Sands added as separate aquifer unit.
Model does not extend below Prairie Fm. Aquiclude ▪ Assumed minimal communication
due to low vertical K of unit.
▪ Simulating higher salinities (>50,000 mg/L TDS) would require density dependent groundwater flow.
Period Unit Stratigraphic
Model Unit
Hydrostratigraphic Model
Quaternary
1 Late Lacustrine 1 Aquitard
2 Surface Sand 2 Aquifer
3 Grand Centre Till 3 Aquitard
4 Middle Sands 4 Aquifer
5 Intermediate Till 5 Aquitard
6 Empress Channel Sands 6 Aquifer
Cretaceous
7 Labiche Formation 7 Aquitard
8 Pelican/Viking Formation 8 Aquifer
9 Joli Fou Formation 9 Aquitard
10 Grand Rapids Formation 10 Aquifer
11 Clearwater Formation 11 Aquitard
12 Wabiskaw Formation
13 McMurray Formation
(includes Basal Sands)
12 Aquitard
13 Basal Sand Aquifer
Devonian
14 Winterburn Formation (not included)
15 Grosmont Formation 14 Aquifer
16 Lower Ireton Formation 15 Aquitard
17 Cooking Lake Formation 16 Aquifer
18 Beaverhill Lake Group 17 Aquitard
19 Watt Mountain Formation (Top of Elk Point Group)
Base of Model
Prairie Formation
(not included) Keg River Formation
Contact Rapids Formation
Laloche Formation
Precambrian
Review of Cumulative Impacts – MacKay River Watershed
GW Level Data
803 wells with water level data
Well assigned to hydrostrat. units based on screened intervals.
Limited long term temporal monitoring data (GOWN)
17 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Groundwater Submodel Calibration
18 - Summary of Model Development
Unit Number of
Wells (n)
ME (m)
MAE (m)
RMSE (m)
Range in Observations
(m)
RMSE as Percent of
Range (%)
Overburden 236 -1.36 4.40 7.18 509.4 1.4%
Empress 58 -7.01 8.33 2.89 189.5 1.5%
Labiche 4 24.50 25.53 32.78 176.3 18.6%
Viking 42 -9.04 10.67 12.65 38.9 32.5%
Joli Fou 10 -5.24 9.44 10.46 28.5 36.8%
Grand Rapids 53 -8.45 8.58 11.58 94.7 12.2%
Clearwater 114 -5.55 8.97 12.06 188.6 6.4%
McMurray 71 0.56 11.47 19.50 279.7 7.0%
Cooking Lake 2 62.09 89.00 108.52 198.3 54.7%
Overall 590 -3.35 7.86 13.55 524.6 2.6%
200
300
400
500
600
700
800
200 300 400 500 600 700 800
Sim
ula
ted
(m
asl)
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)
Steady-state submodel calibration.
Better calibration in aquifers where data more plentiful.
Review of Cumulative Impacts – MacKay River Watershed
Hydrologic Submodel Development (PRMS)
Based on the USGS Precipitation-Runoff Modeling System (PRMS) code
Fully distributed implementation
200m x 200m cells (196,832 unique cell HRUs)
19 - Summary of Model Development
In each unique cell:
Review of Cumulative Impacts – MacKay River Watershed
Climate Inputs
Precipitation and temperature interpolated on a daily basis over a 2.5km x 2.5km grid ▪ Inverse distance squared weighting
25 year daily climate time series input for each grid cell
20 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Vegetative Cover Classes
26 wetland and vegetative cover classes ▪ 17 types of wetlands
Model parameters assigned by class: ▪ Seasonal Cover density
▪ Vegetation indices
▪ Soil zone properties
▪ Overland flow and shallow interflow parameters
21 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Overland Flow
Overland flow and interflow simulated with a topographically defined cascade network
200x200m cell representation
22 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Lateral Flow Processes
23 - Summary of Model Development
PRMS Soil Zone
MODFLOW Layer 1
MODFLOW Layer 2
• Head Dependant • Saturation Dependant
Review of Cumulative Impacts – MacKay River Watershed
Dunnian Flow Processes: SW/GW Feedback
24 - Summary of Model Development
Groundwater feedback dominates in discharge areas, wetlands and shallow aquifers
▪ GW feedback in up to 60% of the watershed
Complex transient runoff and rejected recharge
▪ Occurs when the water table is at or near surface
▪ Spatially controlled: Tends to occur in stream valley areas
▪ Seasonally controlled: Tends to occur in spring when WT is high
GW discharge to the soil zone can become interflow or overland flow
Overland flow can re-infiltrate downslope: “3D recharge”
U n s a t u r a t e d z o n e
S t r e a m S t r e a m
G r a v i t y d r a i n a g e
R e c h a r g e
G r o u n d - w a t e r f l o w
Review of Cumulative Impacts – MacKay River Watershed
Frozen Ground
New frozen ground module developed for this study ▪ GSFLOW is Open Source!
Based on a modified form of the Stefan Equation ▪ Derived by the U.S. Army Corps of Engineers
Model code follows Emerson (1994)
25 - Summary of Model Development
𝑋𝑓 =86,400𝐾𝑓𝐼𝑓
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
Review of Cumulative Impacts – MacKay River Watershed
Model Calibration and Validation
Calibrated then verified against over 38 year period
A range of hydroclimatic conditions simulated
26 - Summary of Model Development
Validation Calibration
Review of Cumulative Impacts – MacKay River Watershed
Model Calibration and Validation
Hydrologic submodel and the final integrated model were calibrated against streamflow observations at 6 Water Survey (EC) and RAMP stations
Historical observations at discontinued stations were an important source of insight
27 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Model Calibration and Validation Good match to streamflow
observations at study area gauges
Daily Nash-Sutcliffe 0.65
Monthly Nash-Sutcliffe 0.75
Good match to validation period: Model has adequate predictive power
28 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Distributed Results
29 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Distributed Results (GSFLOW)
30 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
GSFLOW GW/SW Outputs
31 - Summary of Model Development
April May
Review of Cumulative Impacts – MacKay River Watershed
GW/SW Animation
Animation shows spring melt and changes in GW levels and streamflow
Click for Animation
32 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
GSFLOW Outputs
Spring change in water levels and streamflow
33 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
GSFLOW Outputs
Spring change in water levels and streamflow
Click for Animation
34 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
GSFLOW GW/SW Water Budgets
Significant inter-annual and seasonal storage effects.
35 - Summary of Model Development
-4
-3
-2
-1
0
1
2
3
4
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg
Flo
ws
(mm
/mo
nth
)
Monthly Average GW Inflows and Outflows - Pre-Development Conditions
Lake Seepage Stream Leakage Surf Leakage Recharge Wells Net Const. Head Net Storage
-20
-15
-10
-5
0
5
10
15
20
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Flo
ws
(mm
/yr)
Simulated Inflows and Outflows by Water Year - Pre-Development Conditions
Lake Seepage Stream Leakage Surface Leakage Recharge Wells Net Const. Head Net Storage
Review of Cumulative Impacts – MacKay River Watershed
Model Development Conclusions
The Mackay GSFLOW model represents the complex transient surface and subsurface process and their interaction and feedback
Extensive submodel development and integrated model calibration was undertaken to all available data
Key aspect of the integrated model calibration: ▪ Directly measured flux input: Precipitation
▪ Directly observed calibration targets: Total measured streamflow and GW heads
▪ Overall water budget must balance – no water is gained or lost
36 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Review of Cumulative Impacts – MacKay River Watershed
ASSESSMENT SCENARIOS: CRITERIA AND RESULTS
37 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
Diversion Scenarios
Baseline: No pumping
Current Conditions: ▪ 4 Operations including 11
pumped wells.
Full-Build Conditions: ▪ 14 Operations including 42
pumped wells.
38 - Assessment Scenarios
Current Operations
Current Operations
Current Operations
Review of Cumulative Impacts – MacKay River Watershed
Land Use Change
Processing facilities and well pads ▪ Assumed to be 100m by 100m gravel
pads spaced 500m on center
▪ Reduced ET, due to the loss of vegetation, increased runoff
Full Build Scenario: ▪ Drill pads are estimated to cover 6% of
the planned project areas;
▪ Roads, pipelines, and facilities cover another 4%.
39 - Recommendations for Phase 3
Review of Cumulative Impacts – MacKay River Watershed
Assessment Climate Period
25 year period includes a range of hydroclimatic conditions
▪ Includes both wet years (1997) and drought years (1998-1999, 2009 and 2011).
▪ 5 year spin-up period before start of assessment
40
Surrogate Climate Period
- Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
GW Sustainability Assessment Criteria
In summary, it was agreed that the sustainable drawdown is 50% of the available drawdown in a confined aquifer. ▪ Threshold selection based on the Alberta Environment Water Conservation and Allocation Guideline for Oilfield
Injection (AENV, 2006)
▪ For unconfined aquifers, 66% of the average saturated thickness was used.
▪ Available drawdown based on average water level determined by 20 year baseline simulation.
Assessment Process: all three scenarios run using the same climate inputs ▪ Only difference is diversions and land use change
▪ Daily outputs for every model cell and stream reach saved for comparison
• Drawdown calculation
• Alberta Desktop Assessment
If, under Current or Full-build development conditions, drawdowns exceeded this threshold on any particular day in a 20 year assessment simulation, the cumulative diversion was considered locally unsustainable.
41 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
Overburden Impacts
42 - Assessment Scenarios
Overburden Aquifers
Layer 1 Drawdowns
Percent of Total Available Drawdown
Review of Cumulative Impacts – MacKay River Watershed
Channel Aquifers
43 - Assessment Scenarios
Empress Formation Aquifer
Layer 4 Drawdowns
Percent of Total Available Drawdown
Review of Cumulative Impacts – MacKay River Watershed
Confined Aquifers
44 - Assessment Scenarios
Viking/Pelican Aquifer
Layer 5 Drawdowns
Percent of Total Available Drawdown
Review of Cumulative Impacts – MacKay River Watershed
Deep Aquifers
45 - Assessment Scenarios
Grand Rapids Aquifer
Layer 8 Drawdowns
Percent of Total Available Drawdown
Review of Cumulative Impacts – MacKay River Watershed
GW Sustainability Assessment
Cumulative GW drawdowns are significant, in particular in the lower highly confined aquifer units
▪ Offset by the fact that lower units have much greater available drawdown
On a watershed scale, GW drawdowns appear to broadly stabilize within the 20 year period, suggesting sustainable water use
Localized zones where drawdown exceed 50% of total available drawdown
46 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
SW Sustainability Assessment Criteria
Alberta Desktop Method: ▪ Simulated frequency-duration relationship is calculated for every reach under baseline conditions
▪ The discharge that is exceeded 80% of the time is the ecosystem baseflow (EBF) component.
ADM Criteria 1: ▪ No surface water diversions are allowed below the 80% EBF threshold
• No diversion allowed when flow is below the lowest flows that occur up to 20% of the time.
ADM Criteria 2: ▪ Above the 80% EBF threshold, up to 15% of the available flow can be diverted.
20 year Baseline simulation used to determine weekly EBF threshold in every stream reach
47 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
SW Sustainability Assessment Criteria
Frequency-duration relationship calculated in the watercourse in a natural state.
EBF Weekly Threshold for Mackay River at Fort McKay:
48 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
SW Sustainability Assessment
Threshold for Mackay River at Fort McKay shown ▪ ADM Criteria 1 - fails for select days, as shown in red
▪ ADM Criteria 2 - never more than 15% diverted
Numerous other stream locations also assessed
49 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
Local SW Effects
While the overall watershed passes the ADM criteria at the Mackay outfall point, local streams fail the 15% ADM criteria ▪ i.e. GW diversions locally induce
leakage that exceeds 15% of the EBF (ecological baseflow)
50 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
Sustainability Assessment Conclusions
In summary, the analysis indicates that projected water use in the study area is broadly sustainable, from both a groundwater and surface water aspect, on a watershed scale.
This conclusion is supported by two findings: ▪ Results indicate that drawdowns do not, on a watershed scale, appear to grow over time
▪ Accumulated streamflow losses do not exceed the 15% ADM threshold along the main channel of the Mackay and Dover Rivers.
The results do indicate, however, that under the full build scenario, cumulative groundwater diversions appeared to create unsustainable local impacts, as measured by both the groundwater drawdown and ADM thresholds.
51 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
Water Budget Comparisons
52 - Assessment Scenarios
-20
-15
-10
-5
0
5
10
15
20
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Flo
ws
(mm
/yr)
Simulated Inflows and Outflows by Water Year - Pre-Development Conditions
Lake Seepage Stream Leakage Surface Leakage Recharge Wells Net Const. Head Net Storage
-20
-15
-10
-5
0
5
10
15
20
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Flo
ws
(mm
/yr)
Simulated Inflows and Outflows by Water Year - Full Build Conditions
Lake Seepage Stream Leakage Surface Leakage Recharge Wells Net Const. Head Net Storage
Pre-development shows how wet and dry years replenish and deplete storage (royal blue)
Full build scenario shows greater fluctuations in storage
Review of Cumulative Impacts – MacKay River Watershed
Water Budget Comparisons Winter pumping depletes storage, replenished by April recharge.
53 - Assessment Scenarios
Full-Build Conditions Baseline Conditions
Review of Cumulative Impacts – MacKay River Watershed
Frozen Ground Response
Frozen soil dynamics significantly affect both surface and subsurface processes: ▪ SW Runoff and Recharge: Enhanced runoff during spring freshet + no winter GW recharge
▪ GW Discharge: Significantly reduced winter discharge to streams and wetlands
• GW heads build up under the frozen ground
54 - Summary of Model Development
Review of Cumulative Impacts – MacKay River Watershed
Insights: Winter Pumping under Frozen Ground
Continuous winter pumping for SAGD operations depletes shallow aquifer storage because there is no GW recharge once the ground freezes
Baseflow discharge in May is subsequently reduced by 50% because the snowmelt freshet must first replenish the shallow aquifer storage.
55 - Assessment Scenarios
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Avera
ge M
on
thly
Gro
un
dw
ate
r D
isc
harg
e t
o
Str
ea
ms (
mm
/ye
ar)
Pre-Development
Full BuildAverage Monthly GW Discharge to Streams
Review of Cumulative Impacts – MacKay River Watershed
Wildfires
Over 6% of the Mackay watershed burned in the last 20 years
2% of the watershed area was represented as a “burned” land cover in the model
April 18, 2016: Air temp 27 deg. C
May 1, 2016 Fort Mac. Wildfire
Does the model tell us something about historic wildfires? ▪ Note: Report, released in March 2016, only
included simulations to the end of 2014…
56 - Assessment Scenarios
Review of Cumulative Impacts – MacKay River Watershed
Wildfire Insights
Storage and shallow GW levels clearly reflect multi-year water budget trends
Historic forest fires appear to have occurred during periods of relatively low water table
Development will locally depress shallow water levels, potentially increasing fire hazard
57 - Assessment Scenarios
371.0
373.0
375.0
377.0
379.0
381.0
383.0
385.0
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Gro
un
dw
ate
Ele
vati
on
(m
as
l)
Surrogate Climate Years
Pre-Development Current Conditions Full Build with Land UseLocation 2 - Surface Sands
Major wildfires
Water Table Elevation
Review of Cumulative Impacts – MacKay River Watershed
Overall Conclusions
58 - Conclusions
Detailed, fully integrated SW/GW modelling can provide significant insight into both cumulative effects and watershed function.
Numerous applications: Local impact assessment, water budgeting, climate change, drought assessment, eco-hydrology and water management, and potentially insight into wildfire hazard.
If we are going to do this, let’s understand the costs and minimize the consequences