applications of integrated models to watershed and sub-watershed scale analysis: a canadian context
TRANSCRIPT
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
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
Interflow
ET
Dunnian Runoff
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
CASE STUDY 1: ORO MORAINE
7 - Case Study 1
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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)
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
Watershed-Scale Integrated Modelling in a Canadian Context
CASE STUDY 2 CUMULATIVE IMPACT OF IN-SITU OIL SAND DEVELOPMENT
16 - Case Study 2
From MEG Energy Corp.
Watershed-Scale Integrated Modelling in a Canadian Context
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
Ath
abasc
a R
iver
Watershed-Scale Integrated Modelling in a Canadian Context
MacKay Watershed: Hydrostratigraphic Model
18 - MacKay Watershed
After AGS Source: Andriashek and Atkinson, 2007
McMurray FM
Oil Sands
Grand Rapids aquifer
Viking aquifer
Empress Channel Sands: Key water supply aquifer
Watershed-Scale Integrated Modelling in a Canadian Context
MacKay Watershed: Overland Flow
Overland flow (runoff/runon) and interflow simulated with a topographically-controlled cascade network
19 - MacKay Watershed
Watershed-Scale Integrated Modelling in a Canadian Context
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!)
20 - MacKay Watershed
Watershed-Scale Integrated Modelling in a Canadian Context
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
21 - MacKay Watershed
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
22 - MacKay Watershed
Watershed-Scale Integrated Modelling in a Canadian Context
MacKay Watershed: Model Calibration
23 - MacKay Watershed
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)
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
Watershed-Scale Integrated Modelling in a Canadian Context
MacKay Watershed: PRMS Sub-model Results
24 - MacKay Watershed
Watershed-Scale Integrated Modelling in a Canadian Context
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%.
25 - MacKay Watershed
Current Operations
Watershed-Scale Integrated Modelling in a Canadian Context
MacKay Watershed: Groundwater Impacts
26 - MacKay Watershed
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
27 - MacKay Watershed
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
Watershed-Scale Integrated Modelling in a Canadian Context
CONCLUSIONS
32 - Wrap Up
Watershed-Scale Integrated Modelling in a Canadian Context
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!
Watershed-Scale Integrated Modelling in a Canadian Context
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
Watershed-Scale Integrated Modelling in a Canadian Context
Questions or Comments? Click for Animation
35 - Section Title