Abstracts

ased on the construction of more than 10 integrated GSFLOW models, is consistent
with these PUB recommendations and their emphasis on basin “form and function”. For
example, in a groundwater-only modelling study, model layer geometry is rarely adjusted
during calibration. Our experience with GSFLOW, however, indicates that shallow system
representation, including layering, soil zones, surficial geology, weathering, unsaturated
zone, perched and water table feedback require that the geologist, hydrogeologist and
hydrologist work closely to refine and even re-conceptualization all aspects of the shallow
subsurface system during calibration. This is illustrated through examples, including a GS-
FLOW simulation of the interconnection between a managed reservoir and a municipal
wellfield. Shallow system process complexity means that estimates of average recharge,
developed without groundwater feedback, may need to be discarded once integrated calibration
has begun. Steady-state groundwater sub-models, constructed as an initial step
during integrated model construction, may become obsolete once integrated model development
is complete, particularly in wet season/dry season environments, fluctuating water
table, or locations with significant winter processes. While integrated model development
requires a larger and more diversely skilled modelling team, one of the significant benefits
is that measured fluxes such as precipitation and total measured streamflow can be used
as direct inputs and model calibration targets. This approach is consistent with the PUB
recommendation to de-emphasize empirical flow partitioning methods such as baseflow
separation, and more importantly, provide a common and consistent set of measured flow
targets for both the surface water and groundwater modellers. To conclude, we feel that
integrated models are more than ready to provide the key insights into basin form and
function that the PUB scientists have identified.
199 - Importance of Incorporating Peatlands and Winter
Processes into Integrated Surface-subsurface Models of the
Athabasca River Basin
H.-T. Hwang, Y.-J. Park & E.A. Sudicky
Aquanty, Inc., Waterloo, Ontario, Canada
Department of Earth and Environmental Sciences, University of Waterloo, Waterloo,
Ontario, Canada
Anthropogenic water stresses including climate and land-use change, agriculture and
mining activities in the Athabasca River Basin (ARB) can have significant impacts on
the capacity and sustainability of the existing surface and groundwater resources within
the Basin. An appropriate representation of the key surface and subsurface hydrological
processes, including those relevant to peatlands and winter processes (snow accumulation
and melting) is critical to improve the calibration and predictive ability of models to compute
stream flow, groundwater levels and recharge rates throughout the seasons. The main
objective of this study is to demonstrate the importance of the inclusion of peatland and
cold-season hydrologic processes in integrated surface/subsurface models, with particular
emphasis on the ARB. HydroGeoSphere (HGS), a fully-integrated surface-subsurface
flow and solute transport simulator, is used here for this purpose. The high-resolution 3D
HGS model of the ARB is constructed based on data from the Geological Atlas of the
IAH-CNC 2015 WATERLOO CONFERENCE
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