Towards a climate-driven simulation of coupled surface-subsurface hydrology at the continental scale: a Canadian example

Abstract

The development of new, large-scale tools to evaluate water resources is critical to understanding the long-term sustainability of this resource under future land use, climate change, and population growth. In cold and humid regions it is imperative that such tools consider the hydrologic complexities associated with permafrost and groundwater-surface water (GW-SW) interactions, as these factors are recognized to have significant influence on the global water cycle. In this work we present a physics-based, three-dimensional, fully-integrated GW-SW model for Continental Canada constructed with the HydroGeoSphere simulation platform. The Canadian Continental Basin Model (CCBM) domain, which covers approximately 10.5 million km², is discretized using an unstructured control-volume finite element mesh that conforms to key river basin boundaries, lakes, and river networks. In order to construct the model, surficial geology maps were assembled, which were combined with near-surface information and bedrock geology into a seven-layer subsurface domain. For the large-scale demonstration, the model was used to simulate historic groundwater levels, surface water flow rates (R²=0.85), and lake levels (R²=0.99) across the domain, with results showing that these targets are well reproduced. To demonstrate the regional-scale utility, simulation results were used to perform a regional groundwater flow analysis for western Canada and a water balance analysis for the Laurentian Great Lakes (Superior, Michigan, Huron, Erie and Ontario). The outcome of this work demonstrates that large-scale fully-integrated hydrologic modeling is possible and can be employed to quantify components of a large-scale water balance that are otherwise difficult or impossible to obtain.

Keywords:

• Continental-scale water resources
• surface water and groundwater
• fully-integrated hydrologic modeling
• cold region hydrology
• Laurentian great lakes water balance

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work was funded by the grants from the Canadian Water Network, the Natural Sciences and Engineering Research Council of Canada Discovery Grant and a Tier I Canada Research Chair held by Edward Sudicky. Additional funding includes the Ontario Graduate Scholarship and the University of Waterloo President’s Graduate Scholarship awarded to Jianming Chen and the Ontario Centres of Excellence TalentEdge Post-Doctoral Fellowship awarded to Jason Davison. The research of WR Peltier at Toronto is funded by NSERC Discovery Grant A9627.