This study derives a subwatershed-based lake and river routing GIS product over the domain of Ontario called the Ontario Routing Product (ORP). The ORP is constructed from the Ontario Integrated Hydrology (OIH), HydroLAKES, and MODIS landcover data products. The corrected, high quality OIH flow direction map (~30 m) is the basis for subbasin delineation. The ORP supplies all the necessary hydrological routing model inputs, including network topology, subwatershed geometry, channel characteristics (e.g., slope, length, roughness, and geometry), and lake characteristics (e.g., area, volume, and outlet description). In this routing product, Ontario is divided into nine drainage regions and 35 sub-drainage regions. All Water Survey of Canada streamflow gauging stations within Ontario, outlets from OIH quaternary watersheds, and gauges from the Ontario provincial water quality monitoring network are used to define subwatershed outlets. The resultant high-resolution product has over 90,000 lakes explicitly incorporated and has an average subbasin area of approximately 5 km2. The ORP is archived in GIS-shapefile format and open access. In addition, a set of Python-based post-processing tools are provided, which allows further manipulation of the routing network. For example, modelers can simplify lake and subbasins by decreasing their resolution and can also easily extract specific sub-domains from the Ontario-wide routing product for local applications. This product offers an easy and realistic way to build hydrological models with a large number of lakes. More generally, the ORP provides an excellent starting point for any watershed-based study interested in lake and river network connectivity or watershed delineation.
