The RRL hydrograph Method has been shown to be an accurate method of predicting flood flow from areas where the major component of the hydrograph is runoff from paved areas. In the Tropics the unpaved contribution can be considerable. This report describes a network of catchments which were instrumented to provide data for the modification of the method to allow for this unpaved runoff. The unpaved component is allowed for in the modified program by including a linear reservoir sub routine. A comparison is made of the performance of the model with the Rational Method.