Crusting, runoff and sheet erosion on silty loamy soils at various scales and upscaling from m 2 to small catchments
International audience ; Water erosion is one of the most active processes in soil genesis and dynamics. It is also at the origin of significant environmental problems. Soil surface state is one of the most important factors for erosion risk assessment. However, it is not easy to determine the effect of this factor at a large scale. A field experiment was held in Pays de Caux (Normandy, France) in order to study and quantify crusting, runoff and sheet erosion at the cultivated field and catchment scales. We measured crust formation, runoff and erosion during two seasons on 1-m 2, 20-m z and 500-m 2 experimental plots and on a small catchment. Results allow a ranking of the most important factors influencing crusting and erosion at the different scales. They also enable the development of relationships for upscaling from small plot results to the cultivated field and catchment for specific conditions. However, upscaling from plots to catchments is generally difficult and needs to take catchment spatial structures into account. We distinguish between runoff and erosion scale transfer, the latter being at the origin of specific problems that need further research to be solved.1998 Elsevier Science B.V. All rights reserved. R~sum~ L'trosion hydrique est l'un des processus les plus actifs dans la gen~se et l'tvolution de la couverture p6dologique. Elle est aussi aujourd'hui h l'origine d'importants probl~mes d'environnement. Afin de prtvoir les risques et d'estimer les zones sensibles, il est ntcessaire d'&udier l'influence de la dynamique structurale superficielle des sols et des pratiques culturales sur la gen~se du ruissellement et de l'trosion diffuse. I1 est 6galement important de pouvoir 6valuer la signification difftrentes 6chelles des mesures rtalistes h une 6chelle donnte et les possibilitts d'extrapolation spatiale des mesures rtalis6es sur des petites parcelles exptrimentales. On prtsentera ici quelques rtsultats prtliminaires d'une exptrience rtaliste dans le Pays de Caux visant ~t analyser le ...