To study the effects of preferential flow on infilt rated flow and surface runoff in the granite area of the Three Gorges

Yangtze River

China

a soil profile that is not seriously disturbed by human activities was selected in the Quxi watershed of the area as a field experimental site.Preferential flow

infilt rated flow and rainfall were measured by an automatic flowmeter.Surface runoff was measured by an automatic gauge and a thin triangle weir vertically installed at the out let of the watershed.The relationships among preferential flow

infiltrated flow and surface runoff were analyzed.Results showed that during the same rainfall

preferential flow appeared later and stopped earlier than infilt rated flow.The percentage of preferential flow flux over the total infiltrated water can reach 2.40%~ 48.72%.The maximal preferential flow flux can reach 17200 times of that of infilt rated flow

which could increase soil water flux to a great extent.In the same rainfall

the intervention of preferential flow advanced the appearance of peak infilt rated flow

postponed the appearance of peak surface runoff and prolonged the duration of surface runoff.When the amounts of current rainfall and antecedent influenced rainfall are smaller

preferential flow and surface runoff influenced each other more greatly.