Small-scale experiments on soil roughness evolution and first applications to soil erosion risk assessment

摘要

This paper presents experimental data on the geometric and morphometric evolution of small scale soil parcels after simulated cycles of rainfall with the aim to contribute to the understanding of soil roughness dynamics. Furthermore we will show some results on erosion modelling and radar remote sensing application related to soil roughness. Starting from chosen parcels on crops or bare soils, rainfall simulations have been undertaken over repeated cycles of storms in the Chianti region (central Italy). At the beginning of experiments and after each event, a high resolution DEM of the parcel was automatically generated by means of a recently developed digital stereo-photogrammetric ground-based technique. At the same time, sediment yield and runoff were measured. Initial topographies could basically be considered as random space functions with quasi-isotropic distribution of the micro-relief. In a second phase, the DEMs have been reciprocally compared and elaborated to produce an evolutionary sequence of small scale relief which has been studied and analysed in order to show how the experimental data can be explained in terms of roughness and landscape evolution. The results of the study were subsequently used to calibrate remote sensed radar data derived from SAR Shuttle missions in order to include the roughness parameter in the backscattering models. At the same time the computed roughness was used to derive the friction coefficient f in interrill areas for the application of hydrological-erosive models to assess the soil erosion risk in the area.