A river flow routing scheme for general circulation models

The routing of runoff estimates from General Circulation Models (GCMs) is i mportant to model river flow from large river basins and to estimate freshw ater inflow into the oceans. Present routing approaches use arbitrary const ants and empirical equations to determine travel times between the GCM grid cells. A new river flow routing scheme is developed, which uses physical c atchment and river channel information and river discharge data. The scheme uses surface runoff and deep percolation data from land surface parameteri zation schemes, and routing is performed via linear surface and groundwater reservoirs. Geomorphological relationships between mean annual river disch arge and other physical variables are used to interpolate existing informat ion to define the channel morphology for the digital river networks at the routing model resolution. Applications of the routing scheme to the Mississ ippi and Amazon River Basins indicate that it performs adequately. The sche me does not require the calibration of parameters and can thus be easily us ed in GCMs.