Several rainfall-runoff models were investigated in order to select a precipitation excess generator for an implicit flood routing scheme for the James River. The Maury River basin was chosen for testing the model. Because of ease of application and data requirements, an antecedent precipitation index type of model was selected.

The model utilizes two equations to predict total storm runoff from storm and lumped basin parameters. Five coefficients describe the basin's hydrologic behavior and the storm parameters include precipitation, API, and week number.

Calibration was performed by optimizing the basin coefficients by the method of steepest descent. After minor modification the model was utilized to predict six hourly incremental runoff. By applying unit hydrograph theory, a streamflow hydrograph was computed.

The model was tested for the August 1969 flood. Agreement between computed and observed hydrographs was good with regard to the magnitude of the peak flows and the overall timing, but the computed runoff volume was considerably greater than the observed volume.