THE ROLE OF VEGETATION IN THE RETARDATION OF RILL EROSION

Large rills with catchment areas measuring tens to hundreds of square metres pose serious soil erosion problems to South China, after defore station has exposed the deeply weathered granitic slopes to the impact s of tropical rainstorms. Runoff and sediment discharges of rips respo nd rapidly to rainfall, but compared with bare rills, vegetated rills show considerably lower amounts of flow and sediment yield from unit r ainfall input. Rainfall interception is one main reason for reduced ru noff, and enhanced infiltration also lowers surface flow from vegetate d areas. Potential sediment yield from unit runoff is greatly reduced when the rills are grown with fern, and this provides a far more effec tive mechanism for soil erosion control than the more temporary measur es of installing sediment traps along the rills.