Stormflow generation was studied in a two square kilometre, sub-alpine, first-order basin tributary to Ryan River, which is in the Pacific Ranges of the Coast Mountains of British Columbia. Preliminary field work suggested that neither saturation overland flow nor subsurface stormflow were important mechanisms of stormflow generation Hortonian overland flow appeared to be dominant. The infiltrability of the soils dropped considerably during storm events. Three possible causes of this decline

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... e considered initially: (1) a reduction in capillary gradients as wetting proceeds, (2) a textural contrast in the profile, and (3) air entrapment. All of the preceeding were rejected on the basis of more detailed observations. Instead, it was proposed that a water-repellent layer existed near the top of the soil profile. Laboratory experiments conducted on intact soil samples demonstrated that a repellent layer on the order of a few centimetres thickness did exist near the soil surface. The implications of this finding for infiltration and stormflow generation are discussed.