Using the results of a fully three-dimensional model of variably saturated flow on a heterogeneous hillslope, the concept of equivalent homogeneous hillslopes is explored. By considering single realizations of random patterns of saturated hydraulic conductivity, attempts are made to determine single effective hydraulic conductivity values capable of reproducing both subsurface and surface flow hydrographs. For the case of high-permeability soils, effective parameters were found to reasonably reproduce the hillslope hydrograph, although there was no consistent relationship between the effective values and the moments of the spatial distributions. For the case of low-permeability soils, characterized by surface flow domination of the runoff hydrograph, single effective parameters were not found to be capable of reproducing both subsurface and surface flow responses. Furthermore, the event dependency of effective conductivity values under such conditions was demonstrated.