SIMULATION OF STREAMFLOW IN A MACROSCALE WATERSHED USING GENERAL-CIRCULATION MODEL DATA

General circulation models (GCMs) currently perform vertical water and energy balances at 20- or 30-min time intervals for grid points 2-deg rees-4-degrees apart but generally contain no information on the land- phase transfer of water between grid points or within watersheds. As a result, they operate on an incomplete hydrological cycle. This study combines a hydrological model with a GCM for a macroscale watershed. A water balance was carried out at 12-hour time intervals for a 10-year period using the Canadian Climate Centre GCM II data set for grid poi nts within and surrounding the 1.6 X 10(6) km2 Mackenzie River Basin i n northwestern Canada. The water surpluses from each relevant grid poi nt were accumulated to provide a simulated hydrograph at the outlet of the Mackenzie River. A hydrological model was calibrated and verified using 5 years of recorded climatological and hydrometric data as well as land cover data from classified National Oceanic and Atmospheric A dministration advanced very high resolution radiometer images. The cli matological outputs from the GCM (precipitation, temperature, and evap oration) were then used as inputs to the hydrological model, generatin g a second hydrograph for the Mackenzie River. The results show that u sing the hydrological model with the GCM data produces a better repres entation of the recorded flow regime. The study provides a means of ve rifying the performance of the GCM and is a first step in developing a continental-scale hydrological model which will, ultimately, form a p art of a full model of the global hydrological cycle.