CONTROL OF SOIL EROSION--ROLE OF VEGETATION. PROCEEDINGS OF A SYMPOSIUM ON SOIL EROSION AND ITS CONTROL, REGENTS COLLEGE, REGENT'S PARK, LONDON, APRIL 21, 1989

This paper describes the physical effects of vegetation that can help prevent soil erosion. These can be broadly split into hydraulic and mechanical influences, and can act in one of three ways: (a) at the boundary between the atmosphere and the soil; (b) affecting the movement of water in and out of the soil; and (c) as a physical intrusion into the soil. Soil surface effects include the modification of surface water during heavy rainfall the protection of the soil from raindrop impact; and c) modification of air flow. Vegetation increases the permeability of the soil surface by a combination of increased surface roughness, lower soil density and root channels. This produces increased rates of infiltration of both rainfall and overland flow. Vegetation also removes large amounts of water from the soil by evapotranspiration. The result of decreasing soil moisture is to reduce pore water pressure in saturated soils, and to increase soil suction in unsaturated soils. Root intrusion can reinforce the soil and prevent slope failure. For the covering abstract of the conference see IRRD 824252.