Assessment of differences in physical watershed characteristics between gaged and ungaged portions of the Great Lakes basin

Prediction of hydrologic response in ungaged basins often relies on regression relationships between physical watershed characteristics in gaged basins and either calibrated rainfall-runoff model parameters or model-independent hydrologic response indices (e.g. runoff, runoff ratio, baseflow index, etc.). Predictive skill using these types of modeling approaches may be compromised when watershed characteristics in the ungaged areas are substantially different from those in the gaged areas used to establish the regression relationships. In the case of the Great Lakes basin, regionalization may be complicated by characteristics unique to coastal regions. For example, coastal regions of the Great Lakes contain eight large urbanized metro areas (Milwaukee, Chicago, Detroit, Toledo, Cleveland, Windsor, Toronto, and Buffalo), unique coastal wetland areas, and distinctive meteorological conditions (e.g. lake effect snow). This research investigates the extent to which a set of physical watershed characteristics may vary between gaged (inland) and ungaged (coastal) portions of the Great Lakes basin and therefore complicate regionalization schemes. The work is conducted alongside development of a new regionalization scheme for simulating discharge to the Great Lakes.