CANADA1WATER OVERVIEW: A NATIONAL-SCALE HYDROCLIMATOLOGICAL MODELLING INITIATIVE FOR CLIMATE CHANGE IMPACT ANALYSIS

Assessing the impact of climate change on Canada’s water resources requires a national solution that considers both groundwater (GW) and surface water (SW). The Canada1Water (C1W) initiative addresses this need through the use of HydroGeoSphere (HGS) fully-integrated GW-SW models that collectively provide complete coverage for drainage basins over continental Canada and Baffin Island. In addition to HGS, C1W is utilizing regional climate modelling conducted with the Weather Research and Forecasting (WRF 4.3) model and land surface modelling conducted with the Community Land Model (CLM 5) to generate future climate projection ensembles and thermal regimes for the GW-SW models. Spatial resolution among models varies, with HGS resolving Strahler order 4+ rivers in a 3-D unstructured mesh with <1 to 5 km edge lengths, while WRF and CLM are running on 12.5 km and 5 km regular grids, respectively. For computational efficiency, and to accommodate distinct regional differences in physiography and hydrological characteristics, the continental-scale area of interest has been divided into seven HGS model domains that align with 7 major drainage regions; with areas ranging from 800,000 to 2.3 million km². Each of the HGS models contains between six and eight subsurface layers that incorporate spatially varying hydraulic properties reflective of mineral and organic soils, and surficial and bedrock hydrostratigraphy. Results from C1W will help quantify changes in surface and subsurface hydrologic conditions at mid- and end-century time frames under an ensemble of climate projections. C1W model data sets and model outputs will be published under an Open Government Data licence.