RECENT DEVELOPMENTS REGARDING THE INFLUENCE OF SOIL SURFACE CHARACTERISTICS ON OVERLAND-FLOW AND EROSION

Recent developments in modelling overland flow and soil erosion, which permit the consideration of soil surface characteristics, are reviewed. The models of overland flow are found to be sensitive to soil surface micro-topography and surface pore structure. The former affects depressional storage and hydraulic routing and the latter soil hydraulic properties, notably infiltration rate. The models of soil erosion by water are found to be sensitive to surface roughness, strength and the aggregate size distribution, and the deposition characteristics, of the eroded sediment. Methods for describing the roughness of a soil surface are described and the links to the above processes discussed. The implications of new techniques of roughness measurement for this area of research are briefly examined. It is concluded that the new models of erosion and overland flow provide a more realistic description of the influence of soil surface characteristics than previous semi-empirical models. The review identified the case of large form roughness and shallow flow as a poorly described regime. It was also concluded that the relationship between structural degradation and surface roughness warranted investigation.