ABSTRACT
Hydrological monitoring carried out within humid regions has revealed that runoff generation is spatially non-uniform even within small watersheds carved out in lithology which is homogeneous. Runoff generation, responsible for storm channel flow, was found to be limited to the channel and riparian areas where saturated or nearly saturated conditions eliminate or inhibit infiltration losses (Hewlett & Hibert 1967, Whipkey 1967, Ragan 1968, Betson & Marius 1969, Dunne & Black 1970, Weyman 1970, Anderson & Burt 1978, Dunne 1978, Anderson & Kneale 1980). Similar conditions are unlikely to occur in dry areas. The paucity of rainfall and limited rainfall amounts, coupled with high infiltration losses in the dry channels, prevents the development of saturated or nearly saturated conditions in semi-arid or arid watersheds. Hillslope runoff is thus regarded as the main contributor to storm channel runoff, representing an essential stage in the initiation and development of any channel flow.
